Home Shell of the Naked Hermit Crabs

Ecosystem - Coral Reefs

2007-09-07T00:36:00.001+08:00

Question Time:What is your favourite seafood? Name them.

Link your answer to introduce the first Naked Fact!
Naked Facts:

NF#1: City under the sea!
a) Coral reefs are homes/shelter to nearly one quarter of all known marine species. They include over 4000 species of fish, 700 species of coral and thousands of other forms of plants and animal life.
b) Seafood like groupers, snappers, grunts, wrasses and many more will be gone if coral reefs disappear. Now we won't want that, right?
NF#2: More information about Corals, click here.

Ecosystem - Mangroves

2007-09-05T00:36:00.002+08:00

Naked Facts:

NF#1: Read them from here !
Great and important facts! Do read them.

NF#2: Seagrasses need the mangroves.
a) Mangroves can slow down the speed of water from inland, therefore causing fine silt to settle around the mangrove forests.
b) But if these fine silt reach the waters, they will cloud the water, block the sunlight and the seagrasses will not be able to make food (photosynthesize) and flourish.
NF#3: No durians with mangroves?Read more about this here.
Did you know?
a) It is believed that the earliest species of mangroves came from the Southeast Asian region.
b) There are more mangrove species in this region than anywhere else in the world.

Too much information
NF#4: Pollution Controller
a) Mangroves help to control some forms of pollution, including excess amounts of nitrogen and phosphorous, petroleum products, and halogenated compounds from reaching the seas. Mangroves stop these contaminants from polluting the ocean waters through a process called rhizofiltration. But the over-existence of these pollutants can kill the mangrove trees.b) Rhizofiltration is the filtering of water through a mass of roots to remove toxic substances or excess nutrients.

For more reading on the importance of mangroves, you may click here.

Related Links:
1. Mangrove Climbers
2. Bushes in the mangroves

Ecosystem - Coastal Forest of Chek Jawa

2007-09-05T00:13:00.000+08:00

Naked Facts:

Interactive Question:
Question: Now let's observe, can you find any differences between the coastal forest and mangrove forest?

Possible Answers:
1) The mangrove forest is sometimes submerged in seawater while the coastal forest is not submerged in water.
2) The roots of the mangrove trees have weird roots (you can talk more about them at the mangrove forest) while the trees at the coastal forests do not.

NF#1: Source of Nutrient AKA Food for marine life at the shore
a) When it rains, nutrients from the soil, fallen leaves etc and minerals from the rocks are washed down the slopes of the coastal forest
b) These are in fact considered ‘food’ for many marine flora and fauna living in the inter-tidal zone.

NF#2: Natural wind buffer
a) Imagine a natural wall which is steep and built up of rocks and vegetation.
b) It helps to lessen the impact of strong winds from storms, hurricanes etc.

NF#3: Place to find rare and unique plants + jungle fowl
a) The plants you find at coastal forests can be given the titles of ‘survivors’, as they are constantly exposed to strong dry winds, salt sprays, the hot temperature.
b) Due to development, we do not have a lot of places left in Singapore with coastal forests now, think Labrador Park, Sentosa and Chek Jawa.
c) Native Jungle fowls are also known to live the coastal forest of Chek Jawa.
d) Some rare/unique plants found at the coastal forest include the Seashore Nutmeg, Pong pong tree and Delek air tree etc. Read more about them here.

More reading:
To read on showy and interesting plants found at the Coastal forest, click here.

Simple Drawing on coastal forest ecosystem, worth a look!
http://www.eart-h.com/text/hillpix.htm

Reference:
http://www.eart-h.com/text/sea4rest.htm

The Great Flood at Chek Jawa

2007-08-20T11:54:00.000+08:00

NF#1: In January 2007, Singapore experience some of the heaviest rainfall in 75 years. The rain was just as severe in Johor, and the Johor River was bloated with rain water, which it eventually released into the Straits of Johor.

NF#2: On 18 January 2007, there was a public walk at Chek Jawa, and Adelle from Nparks informed the other regular guides that a lot of animals have died. We suspected that due to the heavy rainfall, Chek Jawa was flooded with freshwater, and it is known that most marine animals could not survive well in water with low salinity. Animals like the carpet anemone simply exploded from taking in too much freshwater, others like sea stars and sponges turned black and died, and many of the snails just died and decomposed into black liquid in their shells.

An exploded carpet anemone.

A dead knobbly seastar.

A decomposed noble volute.

NF#3: Kok Sheng from NUS is conducting a study on the mass mortality and recruitment of macrofauna for example like carpet anemones. This project also lays the foundation for the long-term monitoring and understanding of Chek Jawa.

More information at:
- 18th January
- Death Note from Chek Jawa
- First TeamSeagrass Field Orientation at Chek Jawa
- Chek Jawa Mortality and Recruitment Project

Chek Jawa Boardwalk

2007-08-20T11:16:00.000+08:00

NF#1: The CJ boardwalk was constructed in about 18 months, but the impact on the rich seagrasses and sandflats was minimal. This is because the barge only brought in the construction material for the workers to do the piling during high tide, and when the tide got lower, it returned to deeper waters.

Interesting note: We started seeing oysters, mussels and barnacles on the pillars just weeks after they were placed! And we had seen healthy sea anemones growing just next to the pillars! The public walks were only suspended when the floods in January 2007 caused the massive mortality.

Question for Visitors: What material do you think the boardwalk is made of?

NF#2: While the boardwalk looks like it was made from wood, it was actually made from concrete and fibre glass! The mold used to make the boardwalk was made based on real wooden planks.

NF#3: The entire boardwalk is 1.1km long and has 2 sections - the coastal section (600m) and the mangrove section (500m).

Legend of Ubin and Pulau Sekudu

2007-08-17T18:09:00.000+08:00

Naked Fact #1:
Three animals from Singapore -- a pig, an elephant and a frog -- had a challenge to see who would reach the shore of Johor first. Whichever animal that failed to reach the shore would be turned into rock. All three creatures had difficulties swimming the Straits and the frog turned into Pulau Sekudu, while both the pig and the elephant changed into one big rocky island - Ubin.

Naked Fact #2:
Pulau Ubin is originally bisected down the middle by the river Sungei Jelutong. However, due to prawn farming over the decades, the island has been joined together by the mud bunds across the river that form the prawn ponds. Perhaps that would explain why 2 animals form the bulk of Ubin.

Naked Fact #3:
The islet off Ubin that can be seen from Chek Jawa is named Pulau Sekudu which means Frog Island. There is a rock on Pulau Sekudu that resembles a frog. In fact, a smiley face has been painted on the "face" of the rock. However, it looks most like a frog from its side profile.

CARE Message:
Understand and respect the tides.
Pulau Sekudu, like much of the inter-tidal areas of Chek Jawa, is only accessible at low tide. However, the tides can be unpredictable and dangerous especially when the tide is rushing in. The water level can suddenly increase and you can be trapped on the fast-submerging islet before you know it. Accidents have been known to happen so it's always important to check tide tables before going out to shore areas. Safety first!

Jejawi Viewing tower

2007-08-17T11:39:00.000+08:00

NF#1: The tower is 20m tall and allows visitors to get a good view of Chek Jawa and the surrounding areas. Due to it's height, the tower is also a great place to spot birds on nearby trees. This tower can take a maximum of 40 people.

NF#2: The Jejawi Tower is named after the Malayan Banyan (Ficus microcarpa) growing nearby that was as tall as the tower. The Malayan Banyan is a fig tree. As fig trees produce figs very regularly, they are able to provide regular food supplies for all kinds of animals such as birds and monkeys, unlike other forest trees that fruit perhaps once a year or even once every few years. In fact, such large fig trees play a critical role in providing food and shelter, and studies suggest the number of such fig trees limit the number of animals found in a forest.

Interesting Note: To connect visitors to figs, guides who understand Chinese can ask the visitors if they know the popular oldies "榕树下"(pronounced as Rong Shu Xia), which means "Under the Banyan Tree". Or has anyone eaten "无花果"(pronounced as Wu Hua Guo), which is also a fig. Do explain to the visitors that "无花果" actually do flower, just that the flowers are concealed within the fig. And what they are eating is not really the fruit, but a natural container for the flowers and seeds!

Too Much Information:

Figs are pollinated by tiny fig wasp that are mostly smaller than the head of a pin!

The female wasp somehow finds the correct fig tree in bloom, and sometimes, she must fly a long long way!

To get to the flowers, she squeezes through a tiny little hole in the fig. In the process she loses her wings and most of her antennae.

Usually, there are 3 types of flowers inside the fig:
1. Male flowers near the tiny hole
2. Female flowers with short styles
3. Female flowers with long styles

The male flowers are still immature without pollen. As the female wasp moves around in the fig, she transfers pollen she collected from her previous fig to the female flowers.

She will lay eggs in the female flowers with short styles. After laying the eggs, she dies.

After some time, the baby wasps hatch and feed on the plant tissue surrounding them. The males will hatch first. They are wingless but have strong mouth parts.

Meanwhile, the female flowers with the long styles develop seeds.

Once the male wasps become adults, they will seek out the female wasps and mate with them. After mating, the male wasps will chew and enlarge the tiny hole to create a wider tunnel so that the females can depart without losing their wings. The males usually die soon after they enlarged the tunnel.

As the females leave the fig, they pick up pollen from the male flowers that are now mature.

After they leave, the fig ripens and the walls become yummy to eat. Animals eat the fig and disperse the seeds.

Meanwhile, the brave little female wasp flies on to start the whole cycle then starts all over again.

Additional info on fig and fig wasp:
- The Fib Web
- The Last Stand of the Male Fig Wasp
- One Fig, One Wasp? Not Always!

House No. 1 - Chek Jawa Visitor Centre

2007-08-15T14:10:00.000+08:00

NF#1: The Chek Jawa Visitor Centre is also call House No. 1, which is its postal address in Pulau Ubin. This unique building was built in the 1930s for Langdon Williams, the then Chief Surveyor, as a holiday retreat. It is made of masonry and emulates the style of an English cottage, first found in tea planters’ residences during the British colonial era. The building was awarded conservation status on 1 December 2003, and restoration work of the building was completed in 2006.

NF#2: House No. 1 is also the home to rare 2 species of rare bats! The fireplace, which is among the last few working ones left in Singapore, is the home to a colony of rare Pouched Tomb bats. The nearby water tower was retained as another rare species of Malayan False Vampire bats currently resides in it.

NF#3: There used to be another smaller outbuilding. Although newer than the main house, it had to be pulled down as it was no longer structurally sound. Some of its wall facades have been salvaged and incorporated into the toilet block.

Slithery Snakes

2007-08-14T23:56:00.000+08:00

Naked Facts (General information about snakes):

All snakes are carnivorous or you can say they only eat meat.

Some snakes have a venomous bite, which they use to kill their prey before eating it.

Other snakes kill their prey by constriction or called 'wrapping you up and then squeezing you to death'.

Still others swallow their prey whole and alive.

Snakes are covered in scales. Most snakes use specialized belly scales to travel, gripping surfaces.
They shed their skin periodically. The primary purpose of shedding is to grow; shedding also removes external parasites.
Venom VS poison: The term poisonous snake is mostly false - poison is inhaled or ingested whereas venom is injected. A venomous snake is a snake that uses modified saliva, venom, delivered through fangs in its mouth, to immobilize or kill its prey.

Too Much Information:

Unlike other reptiles, shedding for snakes is usually done in one piece, like pulling off a sock, with the snake rubbing its nose against something rough, like a rock, for instance, creating a rip in the skin around the nose and the mouth until the skin is completely removed.
It is a common misconception that snakes actually dislocate their lower jaw to consume large prey. Actually as snakes do not chew their food and have a very flexible lower jaw, the two halves of which are not rigidly attached, and numerous other joints in their skull, allowing them to open their mouths wide enough to swallow their prey whole, even if it is larger in diameter than the snake itself.

Fabulous four (Mangrove) snakes:

Common Characteristics:

All of them are aquatic.
Their eyes are positioned on the top of their heads so that they can remain with their body submerged in water and yet are able to see above the surface.
All of them have poisonous fangs on the back of their jaws, but their venom is not known to have any serious effects on humans.
All of them give birth to living young, and appear to be largely nocturnal in habits.

Dog-faced Water snake or Bockadam, Cerberus rynchops feeds largely on fish trapped in mud puddles during the low tide.

Yellow-lipped Water snake, Gerarda prevostiana, is less common. It specialises in feeding on newly-moulted crabs.

Cantor’s Water snake, Cantoria violacea, is a rarely seen and extremely long species with markings similar to that of the venomous sea snakes (family Elapidae, or Hydrophiidae). It feeds on snapping shrimps.

Crab-eating Water snake, Fordonia leucobalia, is believed to live mainly in mud-lobster mounds and feeds on hard-shelled crabs.

Monitor Lizards: Cleaner of the Mangroves

2007-08-14T23:17:00.000+08:00

Naked Facts:

Monitor lizards are the “cleaners” of the mangrove habitat as they eat anything that they can swallow therefore helping to make sure there is no too much of any living things in the mangrove.
Their long list of 'diet' consists of (here goes): tiny insects, crabs, molluscs, snakes, eggs (of birds and crocodiles), fishes (including eels up to 1m long), rodents, small mouse deer, other monitor lizards and even human faeces. But they are particularly fond of dead bodies.
They have known to eat prey almost as big as themselves: a 1.2m long monitor lizard ate a snake 1.3m long.

Corny Joke: As long you try not to look ‘delicious’, they are not known to consume humans.
Message behind joke: Observe but not disturb them.

The Water Monitor's main hunting technique is to run after prey that it has spotted, rather than stalking and ambushing.
Like snakes, they have a forked tongue that they stick in and out regularly to "smell" their prey and other tasty titbits.
Water Monitor Lizards are highly mobile. They can swim, run faster than most of us can run and even climb trees.
Monitors can survive in habitats (such as the mangrove forests) that wouldn't be able to support other large carnivores as they are cold blooded (If you need to drag time, you might want to explain the difference between warm and cold blooded).

Did you know?

Komodo Dragons are a member of the monitor lizard family, Varanidae.

Too Much Information:

They have been seen swimming far out at sea and can remain underwater for up to half an hour.
They climb to search for food as well as to escape predators. The young usually stay in trees for safety. If cornered up a tree, they will jump into the safety of a stream or river.
As scavengers, Water Monitors keep the habitat neat and tidy, and also control populations of their prey. They in turn provide food for larger carnivores such as crocodiles and birds of prey. Small young Water Monitors are particularly vulnerable even to large birds such as herons.

More about the Monitor Lizard.

R(A) link (Watch how two monitor lizards mate):
http://www.youtube.com/watch?v=XDEnkGBSpyA

Vinegar Crabs aka Tree Climbing Crabs

2007-08-14T22:53:00.000+08:00

Name the Creature Activity (Something you can try with kids if a Vinegar Crab is spotted on a tree):

Guide: "Hey, we have a crab on a tree here (point to crab)."

Guide: "Let's say we want to name this crab, what name would you give it?"

Kid A: "Tree crab?"

Guide: "But how did it get up there?"

Kid A: "Climb! Oh, Tree-climbing crab!"

Disclaimer: Might not work every time.

Naked Facts:

During low tides, you can find them on the forest/mangrove floor feeding on leaves.
During high tides, you can usually find them at a height high enough to clear the water level and they will remain motionless on tree-trunks, leaves or boardwalk legs.
This is probably a predator-avoidance behaviour, especially with the many predatory species of fish and crabs that hunt with the incoming tide. Out of the water, they remain motionless to avoid other predators like kingfishers, monitor lizards and otters.
At night time or dusk, they have been seen climbing up trees to heights of more than six meters to graze on algae as well as eating leaves.

Food fact (1): The Teochew are known to pickle this crab in black sauce with vinegar, and take it with porridge. That’s why they are also called vinegar crabs.
Food fact (2): The Thais like it salted, with the roe or simply fried whole.

National Education: There is a tree climbing crab named the Singapore vinegar crab (E. singaporense), it is a common species of the tree climbing crab (Episesarma) and has entirely red claws. It is commonly sighted in or near mud lobster mounds.

Too Much Information:

They are usually burrowing crabs, digging holes at the base of trees and mud lobster mounds.
They are considered pests of mangrove plantations for their habit of attacking propagules (seeds of the Lenggadai, a threaten species of mangrove).
Tree Climbing Crabs are known to scavenge meat like many other crabs.

Reference and more about Tree Climbing Crabs

Teaching Nature-Study

2007-07-30T18:25:00.002+08:00

Extracts from "The Handbook of Nature Study" by Anna Botsforc Comstock. Written in 1911, the principles she lays out remain fresh and relevant nearly 100 years later!

What Nature-Study Is
Nature-Study is a study of nature; it consists of simple, truthful observations that may, like beads on a string, finally be threaded upon the understanding and thus held together as a logical and harmonious whole. The object of Nature-Study should be to cultivate in children the powers of accurate observation and to build up within them understanding.

What Nature-Study Should Do for the Child
Nature-Study cultivates the child's imagination, since there are so many wonderful and true stories that he might read with his own eyes. At the same time, Nature-Study cultivates in him a perception and a regard for what is true, and the power to express it.

Perhaps half the falsehood in the world is due to lack of power to detect the truth and to express it.

Nature-Study cultivates in the child the love of the beautiful; it brings to him early a perception of colour, form and music.

But, more than all, Nature-Study gives the child a sense of companionship with life out-of-doors and an abiding love of nature.

Let this latter be the teacher's criterion for judging his or her work. If Nature-Study as taught does not make the child love nature and the out-of-doors, then it should cease. However, if the love of nature is in the teacher's heart, there is no danger.

When and Why the Teacher Should Say "I Do Not Know"
No science professor in any university, if he be a man of high attainment, will hesitate to say "I do not know" if they ask for information beyond his knowledge. The greater his scientific reputation and erudition, the more readily, simply, and without apology, he says this.

It is only the teacher in the elementary schools who has never received enough scientific training to reveal to her how little she does know, who feels that she must appear to know everything or her pupils will lose confidence in her.

In Nature-Study, any teacher can with honour say, "I do not know".

But she should not let lack of knowledge be a wet blanket thrown over her pupil's interest. She should say frankly: "I do not know; let us see if we cannot together find out this mysterious thing. Maybe no one knows it as yet, and I wonder if YOU will discover it before I do".

The Use of Scientific Names
This matter is of little importance if the teacher bears in mind that the purpose of Nature-Study is to know the subject under observation and to learn the name incidentally.

If the teacher says, "I have a pink hepatica. Can anyone find me a blue one?" the children, who naturally like grown-up words, will soon be calling these flowers hepatica.

But if the teacher says, "These flowers are called hepaticas. Now please everyone remember the name. Write it in your books as I write it on the blackboard, and in half an hour I shall ask you again what it is," the pupils naturally look upon the exercise as a word lesson and its real significance is lost.

How To Use the Book
Make the lesson an investigation and make the pupils feel that they are investigators. To tell the story to begin with spoils this attitude and quenches interest.

And lots more in the book including
What Nature-Study Should Do for the Teacher
Nature-Study as a Help to Health
Nature-Study as a Help in School Discipline
The Relation of Nature-Study to Science
The Child Not Interested in Nature-Study
The Correlation of Nature-Study with Language Work
The Correlation of Nature-Study and Drawing
The Correlation of Nature-Study with Geography
The Correlation of Nature-Study with History
The Correlation of Nature-Study with Arithmetic

Techniques for reawakening love for nature

2007-07-29T21:39:00.000+08:00

Extracts from "The Lost Language of Plants" by Stephen Harrod Buhner (a great book that you should try to read if you can, I have a copy).

"Human beings, throughout most of their habitation of Earth, have been so completely interwoven into their environment that, until recently, there was no separation between them."

"Such deep interconnectedness to environment is so fundamental to us as a species that, ultimately, it is not possible to understand ourselves as human beings without understanding something of wild nature itself."

"Because experience of nature and other life-forms is so deeply interwoven into our emergence as a species, human beings possess a genetic predisposition for wild nature and other life-forms -- though it must, through specific experiences, be activated".

"Edward Wilson calls this innate feeling or caring for living forms and systems, for nature, biophilia."

"There are holes inside all of us. Emptiness that can only be filled by some of the other life on this Earth. Without filling them, we live a half-life, never becoming fully human, never being healed or whole or completely who we are. Never becoming completely sane."

"The loss of connection to the land, to Earth, leaves the holes with which we are naturally born unfilled. Merely human approaches can never heal them. Pathologies come from the empty hole that are unfilled, from lack of contact and communication with the wild."

"The holes within us possess particular shapes -- that of stone or tree or bear."

"Many people believe we should first establish this reconnection in the young. But I think that the best hope for restoring it is with the grown -- those in whom the impulse for biophilia has been stunted, those in whom the interior wound is deep, those in whom the need is the greatest."

"If simple information were enough to stimulate the experience, a book will do as well. But books do not and cannot do as well."

"Licensed teachers are embedded in a human-centric, we're-the-most-intelligent approach. They are likely to belittle the living reality found in nature."

"The teacher must embody the experience itself, so that the child can observe it in action and the teacher teaches."

Techniques for restroring biophilia

"The restoration of our capacity for biophilia begins with restoring, and supporting, our capacity for feeling."

"Restoring biophilia ... means 'coming to our senses', especially the sense of feeling -- of touch -- of being touched by the world."

"It has nothing to do with theory. Feelings come first, thinking second; thinking in service of feeling."

"This experience cannot be written down or found in books. It can only be developed ... by allowing ourselves to be touched by the livingness of the world, and exploring the meanings we encounter."

"This reconnects us to everything around us -- to everything that generates those feelings. It reweaves us into the fabric of life."

There are 9 exercises in the book, here is one of them.

Exercise 3

Go to a place in nature that you like. (Be sure and take a journal with you.) Choose a place you have been to before. Find the area that you like most and relax. Sit if you want to; get comfortable.

How does this place feel? Try to describe it in words. Be as specific as you can. Go on in your journal at length if you need to. Write down everything that comes to you no matter how silly it sounds. Even if you think it's crazy.

When you're done, allow your eye to rove, to be drawn to whatever one thing is most interesting to you. Look at it. Let your eye explore it, nothing everything about it. The colours, the shape, how it rests or grows in the ground. Its relation to the air around it, to the plants, water, soil, rocks around it.

What feelings do you have? Write them down.

Is there any part of what you are looking at that you like more? Less? Why? Can you tell? Do all parts of what you are looking at generate the same emotion? Different emotions? Write everything down in your journal.

Do this with at least two things that you see. Make sure that one of them is a plant. You can get up close if you want to, place your eye on a level plane, take an insect view. How is the plant shaped, how does it feel to your fingers, how does it smell? What emotions does it generate in you? Write everything down.

Now go to another natural place, different from the first. Sit down and relax. Get comfortable. How does this place feel? Write down everything that you notice. Go on at length.

Does this second place feel different from the first place you sat? How are the feelings different? Which place feels better -- the first or the second? Is there a name you can give the feeling you had at the first place? A name you can give the second? Names that will make clear the difference in feeling that you perceive? If you can't think of a word make something up.

When you are finished, as you did last time, find something your eye is drawn to and write down everything that you feel and perceive. Do this as well with two other things, at least one of them a plant.

Each place on Earth has unique feelings associated with it, as does each thing that grows or resides there. The number of shadings of their emotional nuances run into the thousands. Each can fit into a specific space within the different human beings that need them. There is a richness in feeling, a companionability that comes from perceiving, the complex interweaving of emotional textures that reside in the life that surrounds us.

Half a beak is better than none?

2007-07-26T19:48:00.001+08:00

The halfbeak is so named because its lower jaw is much longer, while its upper jaw is short and triangular. "Hemi" means half; while "rhamphos" means beak or bill in Greek. The jaws have several rows of small teeth and the tip of the long, spike-like lower jaw is often brightly coloured. The eyes are relatively large and scales are large too.

Halfbeaks are well adapted to living at the water surface. Usually darker on the top while the sides and underside are silvery. This camouflages it from above-water predators looking down on it, as well as underwater predators looking up at it. Its unfish-like body shape also means it is often dismissed as floating sticks. Some small ones are brown and twig-like.

Halfbeaks eat things that float on the surface such as algae, tiny animals like zooplankton and other fishes. Some halfbeak species eat land insects that might fall into the water, while others eat seagrasses and algae.

Snails and clams of the mangroves

2007-07-26T19:47:00.001+08:00

Telescopium snail (Telescopium telescopium) Family Potamididae

It is also called 'Rodong' or 'Berongan' in Malay. 8-15cm. It can stay out of water for long periods of time. It eats detritus and algae, using its highly extendable proboscis to gather edible bits from the mud surface at low tide. It is eaten in some places and is said to be delicious when steamed and eaten with chilli.

Belongkeng snails (Family Ellobidae)

Ellobium sp. on the left is usually found on the ground.
Pythia sp. on the right is sometimes seen on leaves of mangrove trees.
These snails are sometimes seen on leaves and trunks of mangrove trees or on the mud in the back mangroves. They are sometimes also called Mangrove helmet shell snails. Empty shells of dead snails are sometimes also washed up on shores near mangroves.

1-5cm. Shells thick. They breathe air (instead of through gills like most other marine snails) and all lack an operculum to seal the shell opening. They graze on algae growing on mangrove trees and debris.

Mangrove jingle clam (Enigmonia aenigmatica) Family Anomiidae

Like shiny scales, these bivalves are common seen on leaves, trunks and roots of mangrove trees. They usually settle at a height between the high spring and high neap tide.

To about 3cm. The two-part shell is thin and lustrous. Usually oval, sometimes irregular. Colours range from beige, purplish to blackish.

One valve is stuck to a hard surface (leaves, tree trunk, roots) and this valve is usually flat. The other valve is usually slightly conical in shape. The valve that is stuck to the hard surface has a notch or hole in it. The animal secretes byssus threads through the hole to stick to the hard surface. A young animal is more mobile and can move around by using its extendible foot. A young animal is relatively broader than a more mature animal.

Fiddlers: macho crabs of the shore

2007-07-26T19:38:00.001+08:00

The Big Useless Claw Story
Messages: "every inch of the shore is alive, every step kills, stick to the death zone"

For a shore walk (you can go straight to Step 3 if you're on a boardwalk)
Step 1: "Stay very still and you will see some interesting animals on the sand. They are very small and very sensitive to your footsteps. If you wave your arms around they will think you are a bird and will hide. Pretend you are a tree and they will come out."

This will make visitors get used to not stomping around. To be still and look carefully for small things that will only come out when there is no disturbance.

Step 2: If it's taking a while for the crabs to come out "While we wait, let's look around us and I'll tell you about some of the special ecosystems we can see on Semakau. Meanwhile DON'T MOVE!"

Step 3: Once crabs are active, "How many claws does the crab have?" Eventually someone will say "One".

Step 4: "Actually it has two claws. The big claw is so big that it misses the mouth. It has a much tinier claw that it uses to feed itself. Can you see one feeding?"

Step 5: "Only the male crabs have one big useless claw. The females have two small claws so they can feed twice as fast."

Step 6: "Why do you think the males have one big useless claw?" Usual guesses: to find food, for fighting, for defence from predators. Explain briefly and clearly why these are not the case. Goad them with "Why do all boys have big useless things? Like sports cars?" Eventually someone, usually a girl or a small child, will say "To attract girls"

If the visitors have been very very still, you can say "These tiny crabs are all over the place. You can see some near your feet too! See!!! Every inch of the shore is alive with creatures. Some of them are small and buried in the sand. Every step we take on the shore will most definitely squash something."

For shore walk
"We have designated a trail on the shore. It is a death zone. Just like any nature park in Singapore. At Sungei Buloh or Bukit Timah, we don't walk anywhere we want to but have to stick to a trail. Otherwise, a larger and larger area will become 'botak' as footsteps kill off small plants and animals.

"To minimise this death zone, please stay close to me and try to stay in a single file."

If you are not the first group "Follow the trail made by the group in front. Then you don't kill things that they haven't already killed."

For boardwalk
"It's great to have a boardwalk, so we can have a look at these animals without killing them!"

Tips on dealing with fiddlers

Please do NOT pick up fiddlers. Visitors will do as we do and not as we say. In any case, if we catch them and put them down far away from their burrow, they will be stressed and may not be able to find protection and then die.

Please do NOT dig up fiddlers either. This is destructive to the habitat, and encourages visitors to dig up everything they want to see. Instead, encourage them to be patient and wait for animals to come out and go about their normal business.

Naked Facts:

The male waves his large pincer in a style and rhythm unique to his species in order to attract the ladies. Fiddler crabs got their name for this behaviour, which resembles a musician playing on his fiddle. Interactive activity: You can do the fiddler movement using one of your arms to demonstrate to visitors how fiddler crabs fiddle.

The eyes of a fiddler crab are mounted on long stalk giving it a good all-round view of the air and the horizon. This is for potential mate, rival and early predator detection. When the crab scuttles back into its burrow, the eyestalks fold down into grooves along the body.

Interactive activity: Use two fingers from each hand to illustrate this point.

The larger claw can be its either right or left claw. If an adult male loses its fiddler claw, the remaining claw grows to the same size as the lost claw, the claw it regenerates becomes the smaller claw.

Sex sells: When a male Fiddler crab succeeds in persuading a female to mate with him, they retire into his burrow. The female may remain there until the eggs hatch. The eggs hatch into free-swimming larvae that drift with the plankton, changing into yet another form before settling down and developing into fiddler crabs.

Too Much Information

Fiddler crab species are distinguished by the structure of the male's enlarged pincer. They are not reliably distinguished by the colour of bodies, pincers. The species of females is hard to distinguish.

Fiddler crabs cannot swim and prefer to breathe air. So at high tide, they hide in their burrows, plugging the entrance with a ball of sand to trap some air inside. However, they need water to keep their gill chambers wet as well as to process their food. They absorb water from the wet sand through hairs on their legs.

Porcelain fiddler crab (Uca annulipes)

Distinguishing features of the enlarged pincer of the male

outer side is smooth and does not have a triangular depression (most observable difference)
the movable upper finger extends past the immobile lower finger.
has a ridge of bumps on inside or the 'palm' of the pincer.

Orange fiddler crab (Uca vocans)

Distinguishing features of enlarged pincer of the male

has a bumpy outer face.
the tips of the claws are flattened and sabre-like.
the immobile lower finger has a long groove on the outside.

Mudskippers: frog, snake or fish?

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Thoughtful question: "Is it a fish, a snake or a frog?".

Fish! "Yes, it's a fish. But how can it move around out of water? How do you think it breathes out of water?"

"How do YOU breathe underwater when you go diving?"

"Just like the way we bring two tanks of air for scuba diving, the fish brings two tanks of water in its gill chambers. Which is why it has such 'puffy cheeks'."

Naked Facts

Mudskippers have to regularly replenish the water in their gill chambers, so they cannot stay far from water. But mudskippers can actually ‘breathe’ (absorb) air through their skin (as long it remains moist) . This is why they often roll in puddles and keep their tails in water, leading some early observers to believe that mudskippers breathed through their tails!

Mudskippers skip by flipping their muscular bodies. They skim over mud as well as the water surface. They can catapult themselves for a distance of up to 60cm and actually move faster on land and on the water surface than by swimming with their bodies in water.

A distinctive and endearing feature of mudskippers is that their huge goggly eyes at the top of their heads. Unlike other fishes, mudskippers prefer to swim with their heads above water, thus giving them a good 360 degree view.

Corny Joke: Their eyes are like a CCTV in action.

Interesting Fact: Mudskippers can also tolerate high levels of toxic substances such as cyanide.

Too Much Information

Gold-spotted mudskipper (Periophthalmus chrysospilos) Family Gobiidae

They tend to move around in groups, often in amusing 'herds', nervously moving just out of your reach. Sometimes they move in a line, following what seems to be the leader.

To about 12cm. Gaily speckled with orange spots on the undersides. The male raises his bright orange-and-black dorsal fin to court females and intimidate rival males. It eats small crabs, prawns and insects.

Giant mudskipper (Periophthalmodon schlosseri) Family Gobiidae

To about 27cm long, it is the largest of our mudskippers. It has a black stripe along the side of its body.

It builds a pool in with deep tunnels in the mud as a nursery for its young. At low tide, they are often in or near their pool. At high tide, they might be seen clinging to mangrove tree roots.

An aggressive hunter, it eats mainly prawns, small crabs and insects. It may even snack on smaller mudskippers!

Yellow-spotted mudskippers (Periophthalmus walailake) Family Gobiidae

To about 13cm long, it has a greyish body with scattered yellowish spots. There are brownish spots on the upper body. The first dorsal fin is reddish with a broad black band and narrow white margin.

It was previously confused for the juveniles of the Giant mudskipper (Periophthalmodon schlosseri). Unlike the Giant mudskipper, the Yellow-spotted mudskipper does not have a broad black band along the body length.

It is said to be nocturnal, leaving its burrow at night to forage and returning to the burrow in the morning.

Assorted smaller mudskippers

We can't really be sure what they are, especially if they are viewed from the boardwalk. They could be juveniles of larger mudskippers or different species of small mudskippers.

Mudskippers are probably the only fish with movable eyelids!
To keep their eyes moist when they are on land, the eyes can be retracted to dip them into water that collects at the bottom of the eye socket. Their retinas have rod receptors above and cones below, giving them colour vision above and monochrome vision below!

They can absorb gaseous oxygen through blood-rich membranes at the back of the mouth and throat and they also absorb air through their skin which is rich with blood capillaries, so long as the skin remains moist.

Killer litter

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'Line' of rubbish usually gathers at the back mangroves or on shores. This is the high water mark.

Thoughtful question: Let's see how many different kinds of rubbish we can see?

Where do you think this litter comes from?

When we DON'T throw litter into the bin, it falls to the floor, goes into the drain, flushes into the canal, then into the sea. Make sure all your litter goes into a proper dustbin.

Litter kills!

Strings and ropes: trap animals that die when the tide goes in or out. Fishes without water, dugongs drown in water.

Plastic bags: turtles mistake them for their favourite jellyfish food. Turtles will die if they swallow a plastic bag. Similarly for balloons, like the ones released during celebrations.

Plastic and styrofoam don't biodegrade. They stay in the ocean for a long long time, breaking down into smaller and smaller pieces. These are eaten by small animals and enter the food chain including our seafood.

For an article about the global impact of plastic in the ocean
Altered oceans: A plague of plastic chokes the seas
By Kenneth R. Weiss Los Angeles Times 2 Aug 06
or text version on wildsingapore

Links to more articles about marine litter on wildsingapore

You CAN make a difference

Throw all your rubbish in the dustbin.
Try to reduce the use of these things that you eventualy throw anyway: plastics, styrofoam, plastic bags.
Join International Coastal Cleanup Singapore. It's NOT just about removing rubbish. It is about collecting data about marine debris. The data is compiled worldwide and used to raise awareness and encourage change in consumer habits and government policy.
See the ICCS results for 2006 7.5 tons of marine debris was collected from 11km of Singapore's shorelines in just one day.

Mudlobster Condo

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Mudlobster formations are found around the old prawn pond and inside the back mangroves (where the Nipah palms start getting abundant).
Three NAKED facts

Question: Can you guess what animal makes those funny volcano shapes in the mud?

naked fact#1: Without mudlobsters there will be fewer plants and animals in the mangroves.

Those volcanoes are the result of mudlobsters that dig deep in the soft mud. As they burrow about, mounds are created without them even knowing what happens above ground. Mudlobsters are seldom seen above ground.

The mound is like a cosy condo for all kinds of animals. These animals make little holes and tunnels to live in. These animals include crabs, ants, spiders, worms, clams, snakes, and shrimps.

Some plants also appear to grow better on these mounds.

Corny joke: The condo even comes with a swimming pool!

Water is trapped in the mound system forming pools which shelter fish and swimming animals at low tide.

naked fact #2: Mudlobsters are like earthworms. As they burrow and dig, they loosen the mud and allow air and oxygen-rich water to penetrate the otherwise oxygen-poor ground. This allows other animals and plants to make use of the mud.

naked fact #3: The Mudlobster is listed among the threatened animals in Singapore as their preferred habitats are lost or degraded. If it disappears, so will its 'condo' and the plants and animals living there.

Other interesting things to look for at mudlobster mounds

How many plants and animals can you see growing on the mound?

How can you tell whether the mound is an old one or one that is freshly made?

How high do you think a mudlobster mound can get? Records are 2m above the ground, which is taller than an adult human being! I've seen mounds at Lim Chu Kang that are as tall as me.

Too Much Information about Mudlobsters

This photo was taken of a mudlobster on Chek Jawa before deferment. It was spotted by Zeehan as we were having lunch on the big rock where the intertidal walks usually start! We don't know why it was wandering about in the open. We brought it to the prawn pond and left it there hoping it will burrow to safety.
Mudlobsters are not lobsters! Mudlobsters (Thalassina anomala) are more closely related to ghost shrimps of the genus Callianasa. A mudlobster can grow to about 30cm long.

What do they eat? No one knows for sure. They are believed to eat mud.

Can eat or not? There isn't really much of a mudlobster to eat. But they are eaten in some places. They are considered a nuisance by fish and prawn farmers as their digging activities undermine the bunds (raised edges of mud) that surround fish and prawn ponds.
Ubin villagers believed that mud lobsters can be eaten to treat asthma, but no scientific study has confirmed that.

Ferocious mud ant! There is a kind of ant that is found on mudlobster mounds that has a really nasty evil malignant bite. It's name is suitably Odontomachus malignus. I've been bitten by these tiny ants before, their bite really hurts! More about them on the Guide to the Mangroves of Singapore

Links
Guide to the Mangroves of Singapore

No durians without mangroves?

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Three NAKED facts

Question: How many of you like durians?

Question: What do you think pollinates the durian flowers?
If no one guesses right away. "I'll give you some clues: the durian flower looks like a pom-pom, it's white and it blooms at night" Eventually someone will guess bats.
naked fact #1: These bats only drink nectar and eat pollen. They don't eat fruits, they don't eat insects.

Question: "How often does the durian tree flower?"
Eventually they will realise once or twice a year. (We get durians year-round in Singapore because we import them from different places)

Question: "So what do these bats feed on when the durian is not in bloom?" If these bats relied only on durian flowers, they would starve to death.

naked fact #2: Mangrove trees like the Perepat (Sonneratia) have similar pom-pom-like flowers. Bats also feed on the nectar and pollen produced by these trees.
Such trees bloom more regularly and thus support a population of these bats. With more bats, more durians are likely to be pollinated.

naked fact #3: Without mangroves we may have fewer or even no durians!

Where to do this story? Preferably where the visitors can see a Perepat (Sonneratia) tree. As it is a long story, don't do it where it's hot, or mosquito-infested.

To ID a durian tree: the long narrow leaves are dull green on the upperside and bronzy on the underside. The branches are somewhat angular and usually sparsely leafed.
Of course if there are durians on the tree, that's a dead giveaway!

Fruits trees of Chek Jawa

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Rambutan (Nephelium lappaceum)
Among our favourite fruits, there are lots of rambutan trees throughout Pulau Ubin. And some on Chek Jawa too.

Jambu bol (Syzygium malaccense)
There are several of these large trees on the way to Chek Jawa and at Chek Jawa. The pom-pom like flowers are bright pink, and turn into oval shaped jambu. Apparently this jambu is very delicate and thus hard to bring to market. So you can only eat it at Pulau Ubin!

Coastal forest specials

2007-07-22T16:30:00.000+08:00

Here are some showy and interesting plants that you might come across in the coastal forest of Chek Jawa.

False coffee plant (Fagraea racemosa)
These tall bushy plants grow under the rubber trees in the coastal forest near Chek Jawa. Once in a while, they produce large white flowers that turn into bright green fruits.

Wild ixora (Ixora congesta)
Called 'Jarum jarum' in Malay, which means 'bunch of needles'. Quite appropriate a name especially before the buds of the orange flowers open. These wild cousins of our garden ixora only bloom occasionally. But when they do, the dark gloomy floor is splashed with colour.

Rattan
These vigorous climbing palms can be seen from the boardwalk. Their antennae-like tips poking out of the forest canopy. Rattans usually have lots of spines everywhere to help them clamber up trees to reach the sunlight. The spines on leaves often catch on forest trekkers' clothing. So the plant is sometimes also called the 'wait-a-minute' plant.

Rattans produce fruits encased in a scale-like covering. Some are edible.

Rare coastal forest trees of Chek Jawa

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These trees of Chek Jawa's coastal forest are considered rare simply because most of Singapore's coastal forest habitats have already been cleared.

Nyatoh tree (Pouteria linggensis)

Pong pong tree (Cerbera odollam)
The Pong pong trees we see on growing our streets are from Malaysia. Our native Pong pong trees are very rare as most were wiped out as our coasts were developed. There are still a few native Pong pong trees on the shores of Chek Jawa, clinging onto the rocky cliffs.
Fruits are poisonous and often used as rat poison and for stupefying fish in small streams. Oil from seeds is rubbed on the body to treat cold, rheumatism and scabies. The latex is applied to sores and also as a remedy for stingray poison.

Delek air tree (Memecylon edule)
There are several of these rare and beautiful trees on the coastal hillside of Chek Jawa. The bluish purple flowers turn into red be

Sea shore nutmeg (Knema globularia)
There are several of these trees in Chek Jawa's coastal forest. Hornbills love to eat the fruits.

Trees on the shores

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Sea almond (Terminalia catappa)

Called 'Ketapang' in Malay, young small trees may be seen on the coast. The broad leaves may all turn red at the same time, giving the feeling of autumn on the shore.

The tiny white flowers turn into almond shaped fruits that are green when young and become brown and woody as they mature.

It is a common wayside tree in Singapore can be seen along Jalan Eunos/PIE going towards Changi and East Coast Park.

The leaves shed twice a year, usually from yellow to orange and to maroon colour and it finally drops off the tree but sometimes drop when it turned yellow. After the crown is bare, new leaves develop, after which the tree flowers. Fruits are also disperse by fruit bats and floats on the sea for days before reaching the shore and germinating.

Fruit has a thick husk and its kernel can be eaten taste which taste like almond. The timber can be used for building houses and boats. Fish hobbyist and some aquarium shops will usually soak these dried leaves into fish tank, especially for fighting fish because it produce tannin which believed to be good for their scales.

Alexandra laurel (Calophyllum inophyllum)

Called 'Penaga Laut' in Malay, this tall tree has beautiful white flowers that turn into round hard fruits. The broad shiny leaves have fine parallel veins.

Bushes on the shores

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Sea hibisicus (Hibiscus tiliaceus)

Can grow quite tall and bushy, identified by the heart-shaped leaves that have tiny slits on the veins on the underside. These slits produce a substance that attracts ants.
The flower is yellow when it first blooms, turning orange as it ages. This develops into a pod that splits open when ripe to reveal little seeds. Small Cotton stainer bugs feed on the seeds and during a fruiting period, there can be lots of these colourful bugs.

Sea lettuce (Scaveola sericea)

The shrub can be quite tall and bushy. Leaves large and waxy. The little white flowers have a unique structure developing into a round fruit.
Chengam (Scyphiphora hydrophyllacea)

A rather small shrub, with small flowers in clusters, developing into oval fruits.

More about some of these plants
on the Guide to the Mangroves of Singapore
Chengam (Scyphiphora hydrophyllacea)
Sea Hibiscus (Hibiscus tiliceus)

Bushes in the mangroves

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Ximenia americana

This shrub can grow quite tall, with fluffy white flowers that turn into oval fruits that ripen to yellow.
Sea holly (Acanthus sp.)

Common low shrubs often growing on mudlobster mounds. Some leaves may not be so spiky, an a single plant may have spiky and non-spiky leaves.
The flowers may be white with blue or purple tinges, developing into cylindrical fruits.

Getting to the root of mangroves

2007-07-22T16:13:00.000+08:00

Three NAKED facts

naked fact #1: Mangrove trees have weird roots!
Question: Can you describe the different kinds of weird roots that you see?
Stilt roots (Rhizophora)
Pencil-like roots (Avicennia)
Knee roots (Bruguiera)

Thoughtful question: Can you think of reasons why mangrove trees have such strange roots?
Imagine you had to stay all your life on the soft squishy mud without moving. And the tide comes in and covers you up. And waves wash against you. What do you think you need to have?

To grow upright and not fall over? Stilt roots!
To breathe when the tide is high? Pencil-like roots! (Stilt roots are breathing roots too!)

Mangrove trees have shallow roots. Those with pencil-like breathing roots form a kind of raft, with thick roots growing horizontally and the pencil-like parts growing upright from these thick roots.
naked fact #2: You can tell what kind of mangrove tree it is by the kind of roots it has!

After explaining, you can remind them along the way and perhaps get them to guess. If they get it right a lot of time you can congratulate them and say they are now very good with mangrove trees!

Stilt roots (Rhizophora)
Straight pencil-like roots (Avicennia)
Conical pencil-like roots (Sonneratia)
Knee roots (Bruguiera)

naked fact #3: Mangrove trees are the root of life, and source of your seafood!

The tangle of roots in the mangroves results in a rich variety of marine life in the mangroves.

Animals to settle on the roots (clams, snails, barnacles), as well as seaweeds.
These provide food for other animals.
Small animals hide among the roots where bigger animals can't get at them.
Roots protect the mud and sand from being washed away by waves. Here burrowing animals can settle down.

Many of our favourite seafood come from mangroves and the seagrass areas near mangroves

Question: What is YOUR favourite seafood?
Stay in mangroves all their lives: Mud crab, mussels, clams
Stay in mangroves when they are young: big prawns, baby fishes of grouper and other fishes. These go into deeper waters when they grow up.
Found in seagrass areas: flower crab, sting ray, baby fishes

Mangrove climbers

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Ant-house plant (Dischidia sp.)

This strange climber often found on mangrove trees, has two kinds of leaves. Smaller, 'normal' looking ones that are still somewhat fat. And clumps of large hollow leaves.
Ants eventually take up residence in these inflated leaves. Here the ants find safety. Meanwhile, the plant benefits by absorbing the leftover food and rubbish that the ants accumulate inside their 'house'. The plant grows roots into these inflated leaves to absorb these nutrients that are rather scarce in a mangrove.

Hoya climber (Hoya sp.)

Another climber with fat leaves, a water-conserving adaptation to the mangrove habitat where freshwater is scarce.
The climber produces a ball of waxy flowers that develop into long narrow pods full of seeds.

Derris (Derris trifloliata)

A climber commonly seen in our mangroves, it often twists around a young tree so the tree trunk becomes deformed as it grows bigger. Eventually, the tree's growth breaks the climber, but the twisted scars remain.
This climber has pretty pink flowers that develop into flat pods.

Links to more about some of these climbers
on the Guide to the Mangroves of Singapore
Common Derris (Derris trifoliata)

Nipah (Nypa fruticans)

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This is a palm, like a coconut palm. But instead of a vertical stem, it has horizontal underground stems with tall leaves sprouting from the stem. The long palm leaves are used as roofing or 'attap' in traditional kampung houses.This palm is the source of 'attap-chee' which is the young seed. The part we eat is the source of food for the seedling (on the right is a photo of a sprouting seed).
This is the long stalk of tiny male flowers that produce pollen. Tiny stingless bees often gather at blossoming male flowers and pack the pollen baskets on their legs full of yellow pollen.
The female flowers are in the form of a ball. The yellow one is ready to attract pollinators through the little slits. This ball then turns into a ball of fruits.
The sap in a branch of blooms is full of sugars. Traditionally, the sap is collected and may be processed into 'gula melaka' or sweet brown sugar, also used in many of our deserts. Or fermented to produce the alcoholic 'toddy'.

Links to more about Nipah
on the Guide to the Mangroves of Singapore
Nipah (Nypa fruticans)

Nyireh (Xylocarpus)

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Nyireh bunga (Xylocarpus granatum)

Flowers are tiny pinkish.

The fruits are large and look like cannon- or bowling-balls! Inside are a few irregularly shaped nuts arranged like a puzzle.
It has buttress roots. Doesn't have pencil like roots.

The timber is used to build boats and make furniture. Bark dyes used on cloths.

Links to more about Nyireh
from the Guide to the Mangroves of Singapore
Nyireh bunga (Xylocarpus granatum)

This is rare
Nyireh batu (Xylocarpus moluccensis)

Perepat (Sonneratia alba)

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The breathing roots are large, conical with pointed tips.
The flowers have hard sepals that are green on the outside and pinkish on the inside. The flowers bloom at night. The petals are small and white. What is seen as a big pom-pom are a bunch of many many stamens (that produce pollen). These usually drop off the morning after the bloom, and the mud may be littered with hundreds of these tiny white stamens.
Fruits rounded, with the sepals forming a star-shape behind them.

More about the role of Perepat in durians

Links to more on Perepat
from the Guide to the Mangroves of Singapore
Perepat (Sonneratia alba)

These are rare
Berembang (Sonneratia caseolaris)
Gedabu (Sonneratia ovata)

Bruguiera

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All Bruguiera have knee roots.Bakau putih (Bruguiera cylindrica)

Flowers small with pale hard sepals and tiny white petals. The petals usually wither away by mid-day.
Seedlings cylindrical, slender with backward pointing sepals (the thing that looks like a crown)

The wood from the tree is used for fish stakes, pilings, railway sleepers, heavy pillars and beams and other construction. It is also favoured as firewood and for conversion into charcoal as it produces the most heat among mangrove woods. The bark is astringent and used to treat malaria, cure fish poisoning, diarrhoea and fever.

Tumu (Bruguiera gymnorhiza)

Flowers with red hard plasticky sepals (sometimes bright red, sometimes pale pink) and brown furry petals. The petals usually wither away soon after blooming.
Seedling short and fat.

Links to more Bruguiera
on the Guide to the Mangroves of Singapore
Bakau putih (Bruguiera cylindrica)
Tumu (Bruguiera gymnorhiza)

This one is rare
Lenggadai (Bruguiera praviflora)

Bakau (Rhizophora)

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All Rhizophora have stilt roots.All Rhizophora have small dots on the underside of the leaf.

Bakau kurap (Rhizophora mucronata) and Bakau (Rhizophora stylosa)
These two species are hard to differentiate in the field.

Flowers more elegant and held on long stalks from the branch.
Seedlings tend to dangle on long stalks from the branch too.

Bakau minyak (Rhizophora apiculata)
Flowers sturdy and stuck close to the branch.
Seedlings long and stuck close to the branch.

Links to more about Bakau
on the Guide to the Mangroves of Singapore
Bakau minyak (Rhizophora apiculata)
Bakau kurap (Rhizophora mucronata)
Bakau (Rhizophora stylosa)

Api-api (Avicennia)

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All Api-api species (Avicennia sp.) have pencil-like roots that are equal in diameter more or less throughout, with blunt rounded tips (compared to Sonneratia which has conical roots with sharp tips).

Api-api bulu (Avicennia rumphiana)
Leaves shaped like a Chinese soup-spoon, furry on top and below.
Small flowers in a compact, cross-like formation. It blooms quite often.
Fruits furry, flattened.

Api-api putih (Avicennia alba)
Leaves long and narrow, white underneath.
Small flowers on a more obvious cross-like formation. Blooms often.
Fruit furry, often with a long tip.
Api-api ludat (Avicennia officinalis)
Leaves shaped like a Chinese soup-spoon, shiny on top and below, not furry.
Large flowers on an obvious cross-like formation. Seldom blooms.
Fruits large and furry, flattened.Secretes salt on the leaves. In dry weather you can sometimes see the salt crystals there.

Links to the common Avicennia
from the Guide to the Mangroves of Singapore
Api-api putih (Avicennia alba)
Api-api ludat (Avicennia officinalis)
Api-api bulu (Avicennia rumphiana)

This Avicennia is rare
Api-api jambu (Avicennia marina)

Seeds of the Sea

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Tide too high to go out yet?
Raining and have to hide in the shelter on the high shore?
Here's some things you can do on the high shore.

Get everyone to collect seeds and other things they they can find. Give them a time limit or they will take forever. Come back and have a look at what they've found.

Three NAKED facts about plant seeds on the shores

naked fact #1: Shore plant seeds are Real Tough!

The seeds of shore plants often travel a long distance in the sea to find new places to grow.

Let's see some of the special ways they have to survive this long and dangerous journey.

Thoughtful question: Imagine you have to travel miles and miles in the sea. What do you need to survive?

Food
Water
Ability to float

Talk about these features for the seeds that you might find.

A: Seedling of the Avicennia mangrove tree, already starting to grow
B: Fruits of the Rhu tree
C: Fruits of the Sea Almond tree
D: Part of the ball of fruits of the Nipah palm, already starting to grow
E: Seed pod of Derris, a climber of the mangroves
H: Part of the seeds found in the round cannon-ball like fruit of the Xylocarpus tree
I: Part of the ball of fruits of the Seashore pandan
J: I have no idea what it is

naked fact #2: Staying with mama until they are teenagers?

Some mangrove seedlings are already half grown when they fall off the mama tree
F: Rhizophoa
G: Bruguiera gymnorrhiza

Unlike other seeds which don't start to grow until they drop off the mama plant.

On some mangrove trees (Rhyzophora, Bruguiera) fruits start to shoot while still on the tree. They look like 'long beans' on the tree. Others like Avicennia are also growing inside the fruit and quickly sprout once they leave the mama tree.

naked fact #3: Being long has its advantages!

Trees have to breathe. Being tall means the seedling gets above water more rapidly and can breathe sooner as the tide falls.

Common misconception: It is not true that the long pointed seedlings fall off the mama tree and stab into the mud to grow. It's not good to grow in the shade of mama, for both mama and baby trees.

Ideally, the seedlings would drop off at high tide and float away lying horizontally. With time, the tip gets water logged and starts to dip downwards. Eventually, when they arrive at a good spot, roots grow from the tip and right the seedling in a vertical position. Leaves then sprout from the top.

Chek Jawa has two beacons!

2007-07-10T15:59:00.000+08:00

Three NAKED facts

naked fact #1: Did you know that Chek Jawa has TWO beacons?!

Everyone is familiar with the Chek Jawa Front Beacon which sits in the middle of the water next to the boardwalk and has become an icon of the place.
But opposite the Front Beacon, up on the hill among the coastal forest, is the Chek Jawa Rear Beacon.

What is the point of this arrangement? Ships on the sea visually line up the Front and Rear Beacons to help them navigate the Straits of Johor. See the big red dotted line in the navigation map below.

naked fact #2: The channel that runs south of Chek Jawa towards Loyang is a major shipping lane. (Point out to a big ship if you see one as you say this).

Some of the kinds of big ships seen include
Container ships
Large navy ships (they are stealthy and a gun-metal grey)
Barges carrying sand

Where are they going? Possibly Loyang shipping area or Sembawang Shipyard; or Pasir Gudang in Johor.

naked fact #3: Other stories you can tell about the Front Beacon.

It is also placed there to warn ships that that part is shallow.

Thoughtful question at high tide: Can you tell which part is shallow? Yes, it's the part that brown or lighter in colour. The blue or darker coloured water is deeper.

Thoughtful question at not so high tide: Can you tell by looking at the beacon how high does the tide get?

LOVE Nature

2007-06-13T23:55:00.000+08:00

When I was guiding at Semakau Landfill, I had thought that it would be nice to have some short, impactful, and yet easy-to-remember acronym that I could use at my debrief for my participants. Finally, about half a year ago, I came up with LOVE Nature. Do feel free to use this in your debrief if you find it useful :)

L - Learn about nature
You can effectively protect and care for nature only if you understand it, or else you may end up doing more harm! You can read nature books, visit online resources (e.g. WildSingapore, blogs etc), and join guided nature walks (Semakau, BWV, CJ etc). For the Naked Hermit Crabs, L also stands for - Leave all nature things behind, but leave no man-made things behind. E.g. Don't collect shells, or the hermit crabs will have to run around naked! And take your rubbish with you when you leave the nature places.

O - Open up and share with others
Share with your friends what you've learned. Put it up in a blog, or invite friends to join nature walks. On top of sharing what can be found at our nature places and how nice they are, please also share about how we can protect them. E.g. The litter such as plasic bags) you throw in nature places may be mistaken as food by the animals, and they may choke and die after eating them. There is also the problem of collecting and poaching from our nature places. If more and more people collect and poach, eventually our future generations will not get to experience seeing and touching these wonderful living things in their natural environment.

V - Volunteer
Play a more active role! There are many ways you can volunteer. You can become a nature guide, or help to monitor seagrass and coral reefs, or help to plant trees, or help to set up and manage exhibitions etc. Visit WildSingapore.com for more info!

E - Express your views through the proper channels
Singaporeans like to complain, and thus when the authorities get too many complaints, they have to do something. So do send in compliments about how much you like our nature places to remain the way they are! And if you disagree with certain things the authorities are doing, express you views through the proper channel. You can send to http://www.reach.gov.sg/, or send to the forum on the papers.

So bascially, what we hope our visitors will do after attending our walks is very simple - just LOVE Nature!

Raffles' pitcher plant (Nepenthes rafflesiana)

2007-05-21T02:17:00.001+08:00

nepenthes rafflesiana lower pitcher
Originally uploaded by budak.

The coastal forest of Sarang Rimau at Siloso has a good number of Raffles' pitcher plants, which grow as mature vines that clamber and dangle from the larger trees. They are a carnivorous plant species and should be not confused with the plants known as Rafflesia, which are also vines but parasites with no leaves but very large flowers (and are not found in Singapore).

Pitcher plants have specialised leaves that form containers with fluid that is able to digest small animals from ants to even vertebrates like rats. The pitchers are an adaptation that allows the plant to survive in poor soils and other environments where nutrients are deficient and where most other plants cannot thrive.

nepenthes rafflesiana upper pitchers
Originally uploaded by budak.

The pitcher even has a 'lid' on top which is thought to help provide shade against rainwater that could cause the pitcher to overflow. Like most other Nepenthes species, N. rafflesiana produces two types of pitchers: upper and lower. The lower pitchers are produced on branches closer to the ground and are goblet-like, with two 'wings' that may serve to stabilise the pitcher on the ground. They are also much more colourful, with a marbled pattern, especially on the edge of the pitcher. Upper pitchers are slim with a tapered end and are produced on the higher vine-like portions of the plant.

Many small animals meet their doom in the pitchers, but there are also a few which can survive or even make a living from the pitcher plants. Some species of mosquitoes (not the disease-causing types) breed by laying eggs in the pitchers, and the larva feed on the remains of victims in the pitcher fluid. A species of crab spider can also be found which specialises on catching insect prey that approaches the pitchers.

Geology of Sentosa

2007-05-18T04:29:00.000+08:00

NF#1: The cliffs of Sentosa appears to be wearing a nice pink layer of blush and this is thanks to the iron within the rocks which acts like make up for the cliffs which are actually made of sandstone. Iron reacts with the constant supply of fresh sea water and result in iron oxide which give it the pinkish reddish glow. It's better than Estee Lauder!

NF#2: The giant balls that look like bird shit littering the beach are actually not natural rocks! They are originally part of the sea wall that people built to prevent further erosion of the cliffs. So instead of eroding the cliff, the waves instead erode the sea wall that sacrifice themselves by standing in front of the cliff. Over time, the sea wall breaks down into pieces and then like any other normal boulders, it becomes smoothened and polished by the waves over decades and centuries.

NF#3: These natural toilets for boys and girls in case of urgent calls of nature are actually natural! They are not made by a kind hearted naked hermit crab to cater to your urgent needs. Instead, they were made by waves over hundreds of years, constantly hitting at the cliffs everyday. First they form little nooks then eventually become bigger caves! Over time, you might even find some have broken off from the cliff to form "stacks" like the Broken Soul Cliff 断魂崖 near Shangri-la!

NF#4: These strips of rocks are not the latest dykes or seawalls built by the government to prevent sea level rise. They are again naturally made coastal platforms. Imagine the beach is made of a giant kueh lapis of alternating hard and soft rocks. Eventually the waves will erode the soft rocks leaving the hard rocks that you are stepping on today!

Nudibranchs: Gems of the Sea

2007-05-14T23:27:00.000+08:00

NF#1: 'Nudibranch' means 'naked gills'. The name comes from the flower-like gills found on the back of many nudibranchs. These nudibranchs use the gills to breathe.

From top-left in clockwise direction, we have the polka dot nudibranch (Jorunna funebris), a marginated glossodoris nudibranch (Glossodoris atromarginata), a bohol nudibranch (Discodoris boholensis) and a pustolose phyllid nudibranch (Phyllidia pustolosa).

NF#2: Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.

Thoughtful Question: Having a soft body without a shell makes the nudibranch very vulnerable to predators. How do you think they protect themselves?

Many nudibranch secretes chemicals when they are threatened. The chemicals may either make them very distasteful or even toxic!

That's why nudibranchs are not good for the aquarium! The chemicals they release may caused the other animals to be very stressed, or even die!

Some nudibranchs are also able to store the stinging cells of the hydriods or other cnidarians they feed on in their cerata.

Many nudibranchs are brightly coloured to warn the predators not to eat them, and some nudibranchs are also coloured to match their surrounding, which allow them to camouflage from the predators.

NF#3: Nudibranchs are carnivores, each species usually feed on a particular type of prey, which is usually something that can't move, like sponges, ascidians, hard corals, soft corals, sea anemones, zoanthids, peacock anemones, sea pens and eggs of other creatures. Some nudibranchs, such as the Gymnodoris nudibranch (Gymnodoris sp.) also feed on other slugs).

Here is a Gymnodoris rubropapulosa.

Too Much Information:

There are four sub-orders of nudibranchs - Doridina, Dendronotina, Arminina and Aeolidina.

Doridina is the biggest sub-order. You can identify dorids from the flower-like gills on its back. Dorids commonly seen on our southern shores include: Jorunna funebris, Glossodoris atromaginata, Gymnodoris rubropapulosa, Phyllidiella nigra and Phyllidiella pustulosa.

Dendronotids are charactierised by the two rows of branch-like structures called cerata on their backs. One of the dendronotids found on our southern shores is Bornella stellifer (see below).

Arminina is the smallest and most diversified suborder. The body is flattened and elongate with a mantle which extends into an oral veil. The gills are often along the side under under the mantle. One arminids seen on our southern shore is Armina semperi (see below).

Aeolids usually has thin bodies with projections (cerata) on their backs. One common aeolid we've seen on our southern shores is Pteraeolidia ianthina (see below).

How they "smell":
Many nudibranchs have two pairs of tentacles. One pair is near the mouth. The second pair is further back and called rhinophores. Rhinophores are believed to detect chemicals in the hunt for prey and mates.

Reproduction:
Nudibranchs are simultaneous hermaphrodites, meaning each slug has both male and female reproductive organs at the same time. They practice internal fertilisation, and do it side-by-side, facing opposite directions. Sometimes, one will act as the male partner and the other as the female. At other times, they may fertilise each other. After mating, they go their separate ways and each lays its egg mass. Nudibranchs usually die after laying their eggs. In some cases, the eggs are laid on or near a food source and the young ) hatch fully developed and commence feeding. In other cases, the young hatch and are carried in the current. They eventually settle unto a food source and continue developing into adults. The juvenile nudibranchs usually have shells, but lose them eventually when they turn into adult nudibranchs.

Copper-banded butterflyfish (Chaetodon rostratus)

2007-05-14T15:02:00.001+08:00

butterflyfish
Originally uploaded by budak.

Together with the anemone clownfish, this colourful fish is probably the leading flagship of coral reef life for many. Many juvenile specimens (1-2 inches long) can be found hiding amongst the seaweeds and seagrasses off Sentosa's shoreline.

Adults reach about 20 cm in length and are popular aquarium fishes in marine aquariums. Unfortunately they don't survive well in captivity as they require a constant and quality supply of live coral polyps to thrive, so it's not kind to either buy them from shops or catch them from the wild.

Their long beak-like mouths are made for plunging deep into coral growth to pluck out small polyps and other sessile creatures. The fish's laterally-compressed body also allows it to dash easily into narrow crevices. At the end of its dorsal fin, a large eye-epot may help to confuse would-be predators that the fish is actually some other larger animal or make them aim for the tail instead of the real head.

Leaf Slugs: Solar-Powered Suckers

2007-05-13T23:31:00.000+08:00

Three NAKED facts

Question for visitor: Do you think this looks just like a leaf? That's why it is called a leaf slug!

NF#1: Leaf slugs belong to a bigger group of animials called the sap-sucking slugs. Instead of breaking off bits of sea weed, munching and eating them, leaf slugs pierce a hole in the algae and suck out the cell contents.

NF#2: Leaf slugs are able to keep keep the algae's chloroplasts (the part that contains chlorophyll), which continue to photosynthesise inside the slug and provide the slug with additional nutrients. That's why they look so green! But don't you agree that being green allow them to blend into so nicely with the surrounding seaweed, and that predators will have a hard time finding them?

Corny Joke: If only we can do that as well, we just need to eat some vegetables and then go sun-tanning to get the nutrients we need! Problem is everyone will turn green though... Quite eerie...

NF#3: Leaf slugs are basically snails without shells. They may look soft and defenseless, but they are NOT! The white specks in its colour pattern are in fact what we call glands. These glands can secrete a milky chemical when irritated, which can make it very distasteful for its predators. It is believed they recycle the chemicals from the food they eat.

Too Much information:
Leaf slugs are not nudibranchs! They are from the order Sacoglossa, which nudibranchs are from the order Nudibranchia. Both, however, are mollusks from the same class, Gastropoda. The leaf slug we usually see on our shores is Elysia ornata (see below).

Reproduction:
Elysia, as with all slugs, are hermaphrodites. They have both male and female reproductive organs which are located on the right side of the head.

Hints for guides:
Leaf slugs are seasonally abundant on our shores. They usually come and go with the hairy green seaweed, bryopsis, which they feed on. So if you see lots of hairy seaweeds, keep your eyes open.

Here's another species of Elysia which we see sometimes.

Angsana: The Breakable Tree

2007-05-13T23:25:00.000+08:00

NF#1: The angsana tree (Pterocarpus indicus) was introduced into Singapore in the early 19th century. It is native to the southern part of the east coast of Peninsular Malaysia. The tree was introduced to provide shade as it is quick growing and easily transplanted.

NF#2: However, mature trees are known to have a weak structure, and break easily, especially during stormy weathers. Being a roadside tree, it is thus a potential hazard for vehicles and nearby buidlings. This is also probably the reason why this tree looks like this now.

Joke: Ahem, this tree always remainds me of some people I know - those who appear strong and hardly outside, but turn out to be weaklings.

NF#3: Angsana wood is said to be the best fine-furniture wood in Malaysia. It is used to make tables, chairs, cabinets, and decorative items.

Too Much information
You will be quite lucky if you can see the flowers, as they usually last for only one day. The flowers are small, yellow and faintly fragrant. They grow in large bunches 15 to 30 cm long.

Fort Siloso: The Only Preserved British Coastal Fortification in Singapore

2007-05-13T22:51:00.000+08:00

Three NAKED facts

NF#1: Built by the British in the 1880s to protect the western entrance to the Singapore harbour, Fort Siloso is the only preserved British coastal fortification in Singapore today. The name 'Siloso' supposedly comes from a Filipino word 'Seloso', which means a jealous person. The original name for Siloso Point was 'Sarang Rimau', or 'The Tiger's Lair', as it was said that tigers used to roam in the area.

Question for Visitors: Have you hear about the story that the Singapore Guns were facing the wrong way (south) when the Japanese attacked Singapore from the north during World War II?

NF#2: This is not true. The guns were not facing the wrong way, but the forts themselves were wrongly located for an attack from the north. The British had assumed that the defense in the north will be well-covered by Peninsular Malaysia. According to records, most of the forts, including Fort Siloso, took part in the battle.

NF#3: The fort complex is often incorrectly described as a tunnel complex, though in actual fact there are no real tunnels at the Fort, but underground chambers. There were stories that there are undersea tunnels that join Sentosa with Labrador Park. However, no one has been able to proof this so far. There are lots of natural caves along the coast of Sarang Rimau though.

Too Much Information:

The Fort was a POW Camp until the end of World War II. When the Japanese surrender in 1945, Fort Siloso returned to British occupancy, and in September that year, it was initially used by the Royal Navy.

The fort was opened to the public as the Singapore Gun Museum in 1975, and the buildings, underground complexes and gun emplacements both wartime and from the early days of Siloso are very well preserved, although some areas were changed to allow ease of access by tourists.

Striped eeltail catfish (Plotosus lineatus)

2007-05-13T21:40:00.001+08:00

catfish small
Originally uploaded by budak.

In the shallow waters off the Rasa Sentosa Resort, one can quite often see what appears to be a dark clump hovering or moving in the water. Upon closer inspection, the black objects reveals itself to be made up of numerous wriggling little fish. These are juvenile eeltail catfish (Plotosus lineatus) which are marine catfish that grow to about a foot long in adulthood. They are known as eeltail catfish because the caudal or tail fin is seamlessly joined to the dorsal and anal fins to form a single undulating fin that propels the fish. Some eels and the flatfish known as soles also have such joined fins.

The juvenile catfish form a virtual ball that swarms over the reef flat as they wander around seeking both food (probably small crustaceans) and shelter. There doesn't appear to be any 'leader' of the pack but they always move about cohesively and defy any attempt to split the group up.

Don't try to touch the catfish though, even if they are mere inch-long fry. They possess venomous glands in the pectoral and dorsal fin spines that can cause very painful wounds. However, they won't attack or sting unless one is silly enough to handle them.

Plotosus lineatus is probably the only catfish species to be found in coral reefs. It's a wideranging species, found all over the Indo Pacific and Indian Oceans.

Marine spider: Sea specialist

2007-05-11T16:28:00.000+08:00

Three NAKED facts

NF#1: The marine spider can really live in the sea! At high tide, it waits in air pockets among the submerged rocks or coral rubble. At low tide, it comes out to hunt! This one has caught a little shrimp!NF#2: The spider can 'walk' on water! Its furry feet repels water. But it doesn't really move very well over water, preferring to forage on dry ground.

NF#3: Threatened spider: The marine spider is listed among the threatened animals of Singapore due to habitat loss.

Hints for Naked Hermit Crabs
These small spiders (1.5-2cm) are quite common. They are more active near dawn or dusk. Look for unusual movement among the rubble.

Wonderful Worms!

2007-05-10T21:44:00.000+08:00

NAKED facts about some worms you might see ...

Giant reef worm (Eunice aphroditois)
This worm can reach 1 metre or longer! Although it looks fierce and scary, it is a scavenger and eats seaweed too. But it can give a nasty bite so do leave it alone.

Corny joke: It has a face that only a mother could love!Hints for Hermits
Giant reef worms are particularly common on Sentosa. They usually live in the large piles of coral rubble, zooming out to snatch a mouthful of seaweed or other titbit before retracting immediately into their hiding places.

Flatworms are ...err... really flat! This large (8-10cm) black flatworm with little spots (Acanthozoon sp.) is commonly seen. It can swim by flapping the sides of its body!Hints for Hermits
Flatworms are EXTREMELY fragile and will disintegrate if handled. They move very quickly too and can disappear in an instant into some crevice.

Bristleworms (Class Polychaeta) are very bristley indeed. Some have glass-like bristles that introduce painful toxins into the skin. These worms are sometimes called fire worms.Hints for Hermits
Bristleworms are sometimes seen in numbers, especially early in the morning. They move actively about. Needless to say, we shouldn't touch them!

Fanworms (Family Sabellidae) Some worms are beautiful! A fanworm has a long wormy body that is tucked into a leathery tube. At the top of its head, there is a feathery fan made up of modified tentacles. Hints for Hermits
Fanworms are found among coral rubble, sometimes in living corals. They are very shy and will instantly disappear at the slightest sign of danger. Have your visitors keep still (avoid casting shadows or splashing around) and the worm might come out again.

Dead snail shells: Violent deaths!

2007-05-10T15:30:00.000+08:00

Violent NAKED facts about dead shells

Stuck in a shelter waiting for the rain to stop? Came too early and the tide is still too high to go out to the flats? Here's some stories of death and violence to entertain your restless visitors with.

First go out and quickly gather some of these shells that tell the story.

(The striped stick at the top left corner is a spine of a sea urchin. Living sea urchins are covered with a skin. When they die, the skin rots and their spines fall off)

Snail shells are generally coiled. (Show some other broken shells of typical snails with their coils exposed).

The cowrie doesn't look like it has a coiled shell from the outside. But inside, it is coiled!

Thoughtful question: Why do you think the top of this cowrie shell is broken?

It was probably crunched off by a hungry crab!

All these shells have similar breaks at the top.

Thoughtful question: What do you think happened to them?

You're right! A crab probably crunched them too!

Many snail-eating crabs have two different kinds of claws. One large crunching claw, and another claw with thin pincers that act like chopsticks to pick out the snail snack.

See the hole in this clam shell? And the break in the other?

Thoughtful question: Oh dear! What happened to these clams?

The hole was probably drilled by a clam-eating snail, like a moon snail. The moon snail produces an acid that softens the shell. It then uses its rough file-like tongue to slowly drill a hole. The clam is then pumped with digestive juices and is sucked up like soup. Yummy!

The big broken clam was probably crunched by a crab.

Turban and Top: telling them apart

2007-05-10T15:20:00.000+08:00

Three NAKED facts

Thoughtful question: Do you think these two snails are of the same kind? Or are they different?
On the right is the Dwarf turban snail (Turbo bruneus, Family Turbinidae)
On the left is the Toothed top shell snail (Monodontia labio, Family Trochidae)

NF#1: To tell them apart, look at their undersides!Two different ways to keep out nasty crabs!

NF#2: Thick door is good On the right is the Dwarf turban snail (Turbo bruneus). The door to the shell opening (operculum) is thick and rounded. The smooth rounded surface makes it difficult for crabs get a grip. And the thick operculum is hard to crack.

The hemi-spherical operculum is called a 'cat's eye'. Sometimes you may come across loose 'cat's eyes' on the beach washed up from dead turban snails.

NF#3: Thin door works too On the left is the Toothed top shell snail (Monodontia labio). It has a single 'tooth' at the shell opening ('Mono'=one and 'dontia'=tooth). Its operculum is thin and flexible. The snail can pull the operculum deep into the shell to make it difficult for crabs to dig them out.

Nerite snails: Let's talk about shells

2007-05-10T15:11:00.000+08:00

Three NAKED facts

Shells protect snails from all kinds of dangers.

Thoughtful question: Can you think of an animal that might want to eat this snail? How about other things that can harm the snail?

Thoughtful question: Let's look at its shape. What does it remind you of? How does this shape help protect the snail?

NF#1: Shell shape: Round and smooth like half a marble, this streamlined shape allows the snail to avoid being washed off the rocks when it is splashed by waves and swept by currents.

It also makes it difficult for a crab to get a grip on the slippery smooth shell, or to crack it. Like a marble, the snail is likely to slip out of the crab's pincers and bounce and roll away!

NF#2: Shut the door! When it is in danger, the snail can quickly retract into its tough thick shell. It also hides in its shell to stay wet, when it is hot and dry outside.

To cover the hole in the shell, it has a tough door (operculum). In nerites, the operculum has an internal peg to lock firmly in place. This makes it difficult for a crab to stick a pincer in and dig out the snail.

NF#3: Colours: Although some shells are colourful, these snails are hard to spot as they blend well with the colourful rocks where they are found.

Thoughtful comment: Shells can be very pretty. Many people collect pretty shells and don't realise how beautiful the living animal is. See, this snail has a striped body! And such cute long tentacles.

Did you know that shells sold in souvenir shops are taken from living snails? The snails are killed for their shells! So please don't buy shells.

Hints for Naked Hermit Crabs

Where to find them? During the day at low tide, nerites usually hide in crevices and shady spots. At night and on a cool wet day, you might see them creeping about on rocks and boulders, especially those covered in algae.

After having a look at a nerite, be sure to put it back where you found it. And make a big deal about doing this. So visitors get into the habit of doing the same.

Often, if you leave a nerite alone upside down on a rock in a shady spot, it will eventually come out. You can then talk about the living animal and not just the shell.

Too Much Information

What do they eat? Nerites graze the thin layer of algae that grows on rocks.

Nerite babies: Nerites have separate genders and engage in internal fertilisation. So they actually have to make body contact to reproduce. Sometimes you can see mating nerites, especially early in the morning, near wet spots on a rock. The eggs are laid in white circular egg capsules. Each egg capsule may have more than 30 eggs.

What are the different kinds of nerites commonly seen on our shores?
A rough identification can be made by looking at the shell's general shape and texture, and especially the underside of the shell and the teeth-like structures at the shell opening (these do not actually function as teeth to chew food). But similar nerites can only be positively distinguished by looking at internal features of the shell and animal.

Ox-tongue nerite snails (Nerita albicilla)
2-3cm. Shell rounded but flared at the mouth, with faint grooves on the upper surface. On the underside of the shell, on the flat portion in front of the shell opening, there are a series of obvious bumps. This surface resembles the tongue of an ox, hence its scientific name. This nerite is not as commonly seen as the following two.
Chameleon nerite snails (Nerita chamaeleon)
2-3cm. Shell sturdy and rounded with a more flattened spire and rough grooved lines on the upper surface. It has very small 'teeth' near the centre of the shell opening. Some have a row of 4 bumps perpendicular to the edge of the shell opening. It comes in a wide variety of colours and patterns, hence its name. It can be seen in large numbers on some of our rocky shores.Waved nerite snails (Nerita undata)
2-3cm. Shell sturdy and rounded, with a more pointed spire and fine smooth grooved lines on the upper surface. The flat area near the shell opening is white with 3-4 distinct 'teeth'. It comes in a wide variety of colours and patterns. It is found together with Chameleon nerite snails, also in large numbers.Lined nerite snails (Nerita lineata)
2-3cm. Shell sturdy and rounded. It is distinguished by the grey shell with neat black grooved lines. It has small 'teeth' at the shell opening. It is more often seen in and near mangroves. Look for them closer to vegetation and in shady areas nearer the high water mark. The scientific names given here are the old ones. Recent books give different genus and species names to some of the snails. I've yet to get confirmation on the current names.

Sponges: Vacuum cleaners of the shores

2007-05-10T14:04:00.000+08:00

Three NAKED facts

NF#1: Sponges are animals! It's OK if you thought sponges were plants. In fact until about 100 years ago, early scientists also considered them to be plants.

NF#2: Sponges vacuum food out of the water. A sponge sucks water into its body and traps edible bits in the water flow. A sponge can filter water many times its body volume in a short time. In general, a sponge can pump water equal to its body volume once every 5 seconds!

NF#3: Sponges are not softies: Although they look soft and are generally immobile, sponges are not as defenceless as they appear. Many sponges have tiny hard spikes throughout their body. Some spikes are like glass needles. In addition, some sponges release chemicals that irritate other creatures (including other sponges) and prevent them from growing over the sponges. Others contain chemicals that taste bad or are toxic, so animals won't nibble on them.

Some sponges might give you a rash. So please don't touch the sponge!

(Possible Visitor Question: But what about bath sponges? The natural bath sponge is a special kind of sponge that does not have nasty spikes. )

In fact, sponges are so well defended that small animals may live inside and on a sponge. These animals also get free 'air-con' from the flow of water generated by the sponge!

Interactive activity: let's see what animals live on this sponge?

This brown sponge is quite commonly seen on Sentosa. It is usually riddled with tiny brittlestars, one brittlestar in each hole, with only its tiny hairy arms sticking out. During the day, however, the brittlestars are usually well hidden and it's hard to see them.
Too Much Information
Besides Naked Hermit Crabs, ordinary people probably won't soak up this information like a sponge (oops...spontaneous corny joke).

A sponge is a simple animal made up of a few types of cells. These cells are largely independent of one another and only loosely held together. These cells do not form tissues or organs, so a sponge does not have a mouth, digestive system or circulatory system.

A sponge is NOT a colony! In the way that a hard coral is a colony of individual animals.

Why are sponges so colourful?
Scientists don't really know why. One suggestion is that the vivid colours of some sponges warn of their toxic or distasteful nature. The colours might also be a kind of sunblock that protect from harmful rays of the sun. Some sponges harbour symbiotic algae that may colour them green, violet or brown.

Some sponges commonly seen on Sentosa

A yellow to brownish sponge with several 'cones'. When out of water, the cones collapse into mounds. If you come across a large submerged sponge, look for the tell-tale signs of the current of water generated by the sponge.
This encrusting sponge can cover an area of 20-40cm of coral rubble and other hard surfaces. Sometimes branches from out of the encrusting base. The surface of the sponge has prickles. It may be yellow, orange, brown or greenish.This sponge resembles a pot! Usually somewhat oval and squat with one or more depressions in the centre, and lumps on the outside. May be yellow, orange or brown.
This sponge forms a smooth layer over coral rubble with irregular bumps and ridges. It has tiny holes. It is usually blue, sometimes violet or greenish.This tiny pink puff (1-2cm) is a sponge! Usually one or two on coral rubble.

Sea slaters: Beach cleanup crew

2007-05-10T13:34:00.000+08:00

Three NAKED facts

NF#1: Sea slaters are NOT cockroaches. They are not insects. They are more like crabs and shrimps (They are crustaceans.)

Sea slaters can be quite colourful and pretty if you take a closer look at them.NF#2: Sea slaters move very fast!

Thoughtful question: How many legs do you think the sea slater has? Any guesses?

They have seven pairs of legs! They have huge eyes and very long antennae. They also have a pair of long 'tails'. So sometimes it's hard to tell which is the front and which is the back end of a sea slater.

Sea slaters only come out at low tide. They are well adapted for life out of water, breathing air directly through 'pseudo-lungs'. In fact, they will drown if kept under water for a long time!

NF#3: Sea slaters help keep the beach clean. They are scavengers, nibbling on whatever recently died on the shore. At low tide, they swarm over the rocks hunting for food. Thus anything that dies on the beach is quickly cleaned up. It's a natural process of recycling.

Corny joke: Don't worry. Sea slaters won't bite or eat you. Unless you are dead.

But sea slaters can't eat up plastic, glass, metal or other man-made litter. There is no natural process to clean our rubbish! We should not litter.

Hints for Naked Hermit Crabs

Sea slaters are often the first things visitors see. Some people may freak out, especially those with a phobia for cockroaches; and if the swarms of slaters are very large.

It's probably best to explain what sea slaters are as early as you can, to pre-empt any hysteria.

I don't know how to catch a sea slater without hurting it or myself in the process. But I find it's easy enough to talk about them even if you don't have one at hand.

You could tell everyone to stand still so the sea slaters come out. This is also a good excuse to get them to practice quiet observation.

Leathery corals: Fried eggs on the Beach!

2007-05-10T12:58:00.000+08:00

Two NAKED facts

Thoughtful question: What does this remind you of? Fried eggs? Surgical gloves?

Corney joke: Don't they look like life from another planet?!

NF#1: Leathery soft corals are a colony of animals. Each animal looks like a very VERY tiny sea anemone with a long body topped with tentacles. The animal is called a polyp. Countless polyps live together in a shared leathery tissue.

Interactive activity: Please don't touch the leathery coral, but let's take a closer look at the surface. Can you see the polyps?

Portions still underwater may have polyps sticking out, and look 'furry'. When exposed to air at low tide, the polyps retract into the leathery tissue. This leaves a smooth surface, with only tiny holes where the polyps are.NF#2: Leathery corals are not softies! Leathery corals are generally not welcomed in a marine tank because they produce substances that stunt or prevent the growth of hard corals nearby. That's why it's probably also best not to touch them.

Too Much Information
Only for the information of Naked Hermit Crabs...

What do they eat?
Some leathery corals harbour inside their bodies, microscopic, single-celled algae (called zooxanthallae). The algae undergo photosynthesis to produce food from sunlight. The food produced is shared with the coral, which in return provides the algae with shelter and minerals.

What are the different kinds of leathery corals?

Leathery corals of the Family Alcyoniidae may have two kinds of polyps.

Autozooids have long stalks with tiny tentacles that emerge from the skin. There are 8 or multiple of 8 tentacles, and the tentacles are feathery.

Siphonozooids don't emerge from the skin and function as water pumps for the colony. They look like bumps on the skin.

The different kinds of leathery corals are distinguished by the kind of polyps they have, not only by the shape of the colony.

Sinularia leathery corals (Sinularia spp.) have only autozooids and do not have siphonozooids. A colony can take on a wide variety of shapes and even the same species may have different forms.Omellete leathery corals (Sacrophyton spp.) have both autozooids with long stalks and siphonozooids. A colony is usually mushroom shaped with a stem or stalk attached to a surface or buried in the sand. The top of the mushroom may be extensively folded so the colony appears flower-like.Lobed leathery corals (Lobophytum spp.) have both autozooids and siphonozooids, but the autozooids have short stalks and often appear as mere tufts of tentacles. A colony is encrusting, that is, the upper surface is the same diameter as the colony base and they do not have a stem or stalk. It may be dish- or bowl-shaped. The colony is thick and generally has lobes, ridges or rib-like structures.

Corals: Rainforests in the Sea

2007-05-10T11:58:00.000+08:00

Three NAKED facts

Thoughtful question: What are these? Animal/plant/mineral?

The answer? You’re all correct!

NF#1: Corals are colonial animals - they clone themselves to form colonies that look like the boulders you see around you! The individual is called a 'polyp' and it looks like an (small) anemone! Animal characteristics include eating and breathing. In the water, especially at night, they extend their tentacles to feed, amongst other things... (like coral warfare - see below for Too Much Information)

NF#2: They are plants too! Like their other sting-ey cousins, corals also contain tiny algae within their tissues called zooxanthellae, that make food from light to share with their polyp hosts. The zooxanthellae are also what give them their pretty colours. If the water temperature gets too hot and the corals get stressed, the zooxanthellae will leave the corals (well it's not currently clear whether they leave or are kicked out or it's mutual), and the corals will 'bleach' - turn a white colour. Bleached corals may eventually recover, if the conditions become favourable and they can survive the stress.

Corny joke: Corals aren't the only things that get bleached. Blonde coral jokes, anyone?

An interactive activity: How do you tell a dead coral from a living one? (Tell them to be careful where they step!)

NF#3: So where’s the mineral part? Each polyp builds a hard skeleton for protection, where it lives in – just like people live in flats. That would make the colony a block of flats! At low tide, the polyps hide inside to keep from drying out. Actually only the thin layer on top remains ‘alive’, this layer can easily be damaged from careless contact, so be careful where you step! Underneath, the dead skeleton (white if freshly exposed, but soon gets covered over by silt and algae growing) left behind is what forms the coral reef structure. Like trees in the rainforest, this structure is where all the other reef animals live!

An interactive activity: How about a bleached coral from a (recently) dead one? (Think about it...a dead coral would just be the skeleton, so you wouldn't be able to see the tissue.)

Colony, and close ups of dead and living sections. The bits of colour in the centre of the dead section are the remains.

Thoughtful question: Why do you think there’s usually a ‘botak’ patch on the top of the coral? What is different about the top and the sides?

How NOT to hug a coral
As living corals are very easily damaged, careless contact by clueless humans can harm or kill them. It is best not to touch the corals at all – this means no poking, or kicking. And be careful where you step!

Helpful hints for Naked Hermit Crabs ...

Where seen?
Everywhere on the lower shore.

Too Much Information!

Only for Naked Hermit Crabs who want to know Don't force feed this info to visitors! They may fall asleep if you do.

What types are there? – a quick and dirty coral ID guide for the coral rookie
Lots of types, sorted visually by growth forms (branching, massive rock-like), the way the patterns on the coral look (brain, maze, round, little holes).

Anemone Coral (Goniopora sp.) has long fleshy polyps that extend out of the skeleton

Plate or Disc Coral (Turbinaria sp.) is plate-shaped, with large polyps sticking out.

Mushroom corals (Fungiidae) - Free-living species are not attached to the reef, unlike most other corals

Branching corals: Pocillopora damicornis (top) and Montipora sp. (bottom)

Stone Corals (Faviidae) are usually shaped like boulders – though there are other kinds shaped like boulders too…

What do they eat?
They get most of their nutrition from their zooxanthellae. Or they also eat plankton, caught from the water using their tentacles.

The secret world - sex and violence (RA!)
How do rooted things make luuuuurve? Like most marine creatures that don’t move around, corals simply release their eggs and sperm into the water! Tide and currents take care of the rest. This is a very coordinated event, in terms of timing, to ensure that spawn from different colonies meet and mix.

Mass spawning is an event happens within the time frame of 2-3h on a few nights every year, where many types of corals (and some other reef creatures too) release their eggs and sperm at the same time! On bigger reefs, this can form spawning slicks on the surface of the sea – like an oil slick but consisting of coral eggs and sperm bundles.

Scientists are still trying to figure out how this extraordinary coordination occurs. The baby corals (like little anemones, or jellyfish) drift on the currents, and eventually settle in a suitable place. The baby polyp will build its home there, and start building a whole new colony!

Colonies spawning (2 photos), and close up of Galaxea egg bundle.

Look for bands of silt-covered dead coral between neighbouring colonies, usu a few cm in width, and quite uniform. This is evidence of coral warfare. On the reef, competition for space can get quite violent, and many corals have special, extra long war tentacles that they use to zap other corals into submission. They then take over the space vacated.

How long do corals live?
This is an interesting question to answer, with regard to colonial animals. It depends on the definition of ‘life’ and ‘the individual’. Because coral polyps divide over and over again, producing essentially the same individual, external factors like predation, disease and environmental conditions aside, they can ostensibly live forever!

Human uses
Directly, coral skeletons (calcium carbonate) have long been used as building material in less-developed places. Coastal reefs are also thought to protect their coastlines from storms.

Indirectly, coral reefs are the habitat and nursery ground of many kinds of seafood. So no corals = no seafood.

Blue coral

Blue coral is a kind of "coral" that has an internal blue skeleton. It's not really a hard coral, as it belongs in the sub-class Octocorallia, along with the soft corals, whereas the hard corals lie within the subclass Zoantharia, which also includes the anemones.

Environmental issues
Corals are quite sensitive to environmental changes, and can only survive within a small range of temperatures and light levels. The recent increase in global temperatures have caused major coral bleaching problems throughout the world in the last decade. This is bad because bleached corals lose their helpful algae symbionts and are prone to die off. You can help the corals by doing your part to live sustainably!

Seagrasses: Meadows in the Sea

2007-05-09T21:13:00.000+08:00

Three NAKED facts

NF#1: Seagrasses are homes to many small animals. Like a meadow or miniature forest, seagrasses provide hiding places for small or slow-moving animals, places for animals to lay their eggs. Baby fishes also shelter here before moving to deeper waters when they grow up.

Interactive activity: Let's see what animals we can see on the seagrass?

Helpful Hints for Hermits
Tape seagrass is longer and has more to look at.

Things commonly seen...
Pinkish or pale stuff growing on the leaves. Could be algae or encrusting animals.
Small snails, tiny hermit crabs.
Tiny crabs.
Eggs (small dots, spirals)
Sometimes, bigger fishes hide among the leaves, e.g., filefishes, eel-tail catfishes.

NF#2: Seagrass roots form a mat on the ground that keeps the sediments down and the water clear. With stable ground, burrowing animals can safely make their tunnels.

We should try not to step on the grass too much. It breaks up the grass and hurts animals living among them.

Corny joke: It's like a grassy field at school. If we play soccer on it every day, some parts will become botak! (bald)

NF#3: Seagrass meadows are an important part of the food chain. Not many animals can eat seagrasses because they are quite tough to chew and digest. But lots of animals graze on the algae growing on seagrasses. As well as hunt and eat the small animals that live there. When seagrasses die and decay, lots of animals eat up the bits that float around.

Thoughtful question: Can you guess what big animal eats seagrasses? (Lead them along) What eats land grasses? (Eventually someone will guess 'cow').

Sea turtles also eat seagrasses.

Too much Information
For visitors who Really Want To Know...

Seagrasses are the only flowering plants that can live in the sea. Like land plants, they have fruits and flowers. (If you want to compare with seaweeds: "seaweeds reproduce in another way, without flowers and fruits").

Some seagrasses you will see on Sentosa

Tape seagrass (Enhalus acoroides) is the longest seagrass found on our shores. Male flowers of the Tape seagrass are tiny (see the small white bits?). They form inside a bract that grows at the base of the plant. During a bloom of Tape seagrass, male flower float everywhere on the water. They look like bits of styrofoam! Sometimes, the male flowers join up to form 'rafts'.Female flowers are large and emerge on long coiled stalks. The pale yellowish petals last only for a day or so. Often, all that is seen are the V-shaped bracts. Soon, the large fruit develops. It is a hairy capsule that holds several seeds. The seeds are said to be edible and are eaten by some coastal dwellers. The raw seeds are said to taste like chestnuts.Spoon seagrass (Halophila ovalis) is commonly seen on many of our shores. Their flowers are tiny and they probably bloom rarely.More about seagrasses on the teamseagrass blog

Seaweeds: Salads of the Sea

2007-05-07T15:40:00.000+08:00

Seaweeds are a tour-saver. If there is absolutely NOTHING else on a shore, there is usually some seaweed. But please do NOT talk ONLY about seaweed. Or discuss each and EVERY kind of seaweed that you see! Unless that is what your visitors ask for.

Three NAKED facts

Interactive activity: Feel this. What do you think this is? (You might want to give them a variety of seaweeds to feel and look at)

NF#1: Seaweeds are algae ('el-gay'). Algae is the scummy green stuff that grows on your bathroom if you don't clean it. Also inside your aquarium. Algae can grow in almost any dark, damp place.

Corny joke: If you don't bathe often, algae will probably grow on you too! (and if the visitors look like they can take a corny dirty joke..."In your dark damp places too!")

In the sea, algae can be very large. And comes in a wide range of shapes, colours and textures.

NF#2: Everyone loves to eat seaweeds. Fish, crabs, snails, slugs, sea urchins eat seaweeds. Even YOU love to eat seaweed!

Thoughtful question: Can you think of seaweeds that you eat? I can bet that you have eaten some seaweed today! Or will eat it today.

Sushi usually comes immediately to mind.

Extracts of seaweeds are widely used to colour, stabilise and thicken commercial food products. If you eat ice-cream or canned food or commercially prepared food, you would have eaten seaweed.

Agar-agar and jelly are also made from seaweed extracts.

NF#3: Seaweeds are slippery and slimy!

Interactive activity: Feel the seaweed!

The slimy coating reduces water loss when exposed at low tide. Being leathery also helps. Seaweeds also protect themselves from being eaten by containing unpleasant tasting chemicals such as iodine.

Weedy Hints for Naked Hermit Crabs

It's probably best NOT to let visitors eat seaweed. Some seaweeds produce natural toxins at certain times of the year. Seaweeds may also concentrate pollutants. Not to mention seaweed gets trampled on by people. And who knows where they have been beforehand.

Snippets of Weeds
Here are snippets on various seaweeds commonly seen on our shores.

Green Seaweed
Hairy green seaweed (Bryopsis sp.)
It can be seasonally abundant. On the Southern shores, it sometimes covers the entire shore in a fluffy green carpet. The carpet may completely disappear in a few weeks, not appearing again for several months.

Various slugs are often found among this seaweed.

Interactive activity: Let's see what animals we can find living in this seaweed.

Green coin seaweed (Halimeda sp.)

Interactive activity: feel the seaweed!

It is made up of little hard coin-like shapes, joined to one another. It is hard because it incorporates calcium carbonate in its structure. When the seaweed dies, the calcium carbonate particles become part of the sandy shore.

In some parts of the world, this seaweed contributes to a large percentage of the sand on the shore!

Sea lettuce (Ulva sp.) ("Ool-va or "Aul-va") It can be seasonally abundant. On the Northern shores it sometimes gathers at the low-water mark forming a thick green carpet. The carpet may completely disappear in a few weeks, not appearing again for several months.

Corny joke: To the question "Can eat or not?", the answer is yes! You can eat it if you are a pig. This seaweed is fed to pigs and other livestock in other parts of the world.

These are green seaweeds! Bubble green seaweed (Boergensenia sp.) on the left, and what I like to call Sea sausage (Neomeris sp.) on the right. But you can give them other common names if you like. Neomeris incorporates calcium.

These feathery stuff are seaweeds and not seagrasses. There are several different species of these feathery green seaweeds, these Caulerpa sertularioides on the left and Caulerpa taxifolia on the right. ("Kah-ler-pah")

Sea grapes are also green seaweeds. Two kinds are commonly seen: Caulerpa lentillifera on the left and Caulerpa racemosa on the right.

Brown Seaweed
Sargassum (Sargassum sp.)
The longest brown seaweed seen on our shores. They are more commonly seen on our Southern shores.

The little 'balloons' are NOT fruits. They help to keep the seaweed afloat. Smaller seaweeds grow on it or among the 'branches'. Sometimes, small animals can be found hiding among the tangles.

Interactive activity: Let's see what we can find on this seaweed!

Mermaid's fan (Padina sp.) ("Peh-die-nah") on the left is more commonly seen on our Southern shores. It incorporates a bit of calcium, forming concentric rings on the seaweed. Some people call it Mermaid's Ear, but I think that's so gross. The lumpy seaweed on the right is Colpomenia sp. which you can call Bubble brown seaweed if you like :-)

Red Seaweed
The prickly red seaweed (Acanthophora sp.) on the left is more commonly seen on our Northern shores. The seaweed that looks like big flat red sheets (Halymenia sp.) on the right is sometimes mistaken for plastic bags.

The pink stuff that grows over coral rubble (on the left) is a red algae! It incorporates calcium and is quite hard. It is called coralline or encrusting algae. Like living cement, by growing over rubble and bits and pieces on the shore, the algae helps to consolidate the reef. The pink stuff grows everywhere, even on shells of living snails. Some coralline algae grow into delicate branching forms that look like a pom-pom! (on the right).

Onchs: Cutest Slugs on the Shores

2007-05-07T15:09:00.000+08:00

Three NAKED Facts

Interactive activity: There are some animals on this rock. Can you find them?

NF#1: See how well camouflaged they are! This is why you should watch your step. You might squash an animal if you're not careful.

Thoughtful question: What do you think these animals are? Worms? Snails? Bugs?

NF#2: Onch slugs are naked snails. That is, they are snails without shells.

Let's look at the underside of one.

See, they have a large broad foot, and a pair of tentacles. Just like other snails. Instead of a shell, they have tough skin.

NF#3: Onch slugs breathe air...through their backside!

Hint to Naked Hermit Crabs: You can sometimes see this backside hole on the underside of an onch. It's (obviously) on the end opposite to the one with the tentacles :-)

Onch slugs belong to the same group of snails like our land garden snails. They have modified gills on their backsides to breathe air. At high tide, they burrow into mud or sand trapping an air bubble to breathe from.

Helpful hints for Naked Hermit Crabs

Onch slugs are more commonly seen on large boulders with a good growth of algae (fuzzy greenish stuff) that they graze on. They are also more plentiful in shady moist parts of the boulder. Or on boulders and hard surfaces under trees. They are more active on cool days. If it is a really hot day, the onchs are probably all well hidden away.

If you can't find the slug, look for the trail of 'processed algae' that it leaves behind. Follow the trail and hopefully you will find an onch at the end :-)

The bigger, flatter, bumpier onch (below) is found on rocks near the low water mark.The smaller, rounder, smoother onch (below) is more often found near the high water mark, usually in shady moist areas on large boulders or rocks with thick growths of algae .
How to Hug an Onch

Be gentle with onchs! Don't force one off a rock if it clings tightly. Choose another one.

Onchs can be darn slippery. Once you manage to get them to un-cling, they tend to drop off suddenly, and as you try to catch them, they squirt right out of your hands. Here is one way to avoid them 'taking the plunge' or losing them among rock crevices. Place a cupped palm UNDER the slug, then gently 'persuade' the onch to let go. It should then fall into your hand.

It is probably best NOT to let visitors handle the onchs. Onchs produce icky slime which might cause problems if kids wipe their eyes or stick slimy hands into their mouths. Also, onchs are rather delicate and kids could injure the onchs.

Limpets: Snails with Hats

2007-05-04T14:56:00.000+08:00

Three NAKED Facts

Interactive activity: I see (insert number) animals on this rock. Can you find them?

Thoughtful question: What do you think these animals are? Crabs? Snails? Bugs?

NF#1: A limpet is a snail with a hat! Like other snails, it has a very broad foot. Instead of a coiling snail shell, it has a hat-shaped shell. To protect itself (from water loss and animals that try to eat it), a limpet uses its broad foot to clamp its hat-shaped shell firmly to the rock. It clings so tightly that you will hurt it if you try to pry it off the rock. So please don't do that.

If they want to see what the limpet looks like under its hat, there's a large photo of this in the Chek Jawa guidebook, pg. 55.

Corny joke: A limpet has a permanent umbrella!

NF#2: Limpets can move. At high tide, they munch on tiny plants that grow on the rocks (algae). The rock surface around a bunch of limpets is usually clear of algae and other animals (like barnacles and oysters).

NF#3: Home on the Rock. When the tide falls and things get dry, some kinds of limpets go back to the same spot, called the 'home scar'. The limpet rubs its shell against the rock on this same spot, wearing away the shell and/or the rock so that a perfect fit is created! Even as the limpet grows bigger!

Sometimes, you might come across a spot on a rock in the shape of a limpet that is completely 'clean' and free of growths. This could be the home scar of a limpet that has recently come to an unhappy end. In the photo above, you can see the feeding trails leading from the home scar.

Some limpets are believed to follow their mucus trails back to the home scar. In some of these homing limpets, their mucus also stimulates the growth of algae!

Too Much Information
Too much limpet info can make ordinary people go limp. Beware!

Two major groups of snails have umbrella-shaped shell. They come from separate groups and are not closely related.

True Limpets
One group of snails with hats called True limpets breathe through gills. Some have holes at the top of their shells, others don't.

Star limpet (Patelloida sacchroides) Family Lottidae
This is a True limpet that breathes through feathery gills. About 4cm, common, usually found on large boulders.

Smooth limpet (Cellana sp.) Family Nacellidae
A True limpet, it breathes through a ring of gill leaflets. 2-3cm, uncommon, usually in shady places near the mid-water mark.

Keyhole limpet (Diodora sp.?) Family Fissurellidae
This is a True limpet that has a hole at the top of the shell. About 1cm, usually found under stones near the low water mark. Water is sucked in from under the shell, passes over the two feathery gills, and is then expelled out of the hole in the shell. Because of this hole, these limpets must live in wetter places.

False limpets

Another group of snails with hats have lungs and breathe air. False limpets (Family Siphonariidae) belong to this group and are closely related to land snails and to onch slugs (Family Onchididae). Because they can breathe air, false limpets are often found higher up on the rocks than limpets that breathe through gills.

Guam false limpets (Siphonaria guamensis) Family Siphonariidae
About 1-2cm, common and usually found on hard surfaces near the high water mark.

Javan false limpet (Siphonaria javanica) Family Siphonariidae
About 1-2cm, common and usually found near the high water mark.

Large false limpets (Siphonaria atra) Family Siphonariidae
About 2-3cm, usually found on large boulders near the mid-water mark. Not commonly encountered.

Barnacles: Pimples on a Rock

2007-05-03T17:02:00.000+08:00

Three NAKED Facts

Thoughtful question: Let's take a closer look at these pimples. Do you think they are living animals? Which animals are alive and which are dead?

NF#1: A living barnacle has a door over the opening in its shell. A dead one has a gaping hole. The glue produced by the barnacle is so strong that its shell usually remains stuck even after it's dead.

Interactive activity: Even after the barnacle is dead, other animals may shelter in the remaining empty shell. Let's see what other animals are living in the empty shell.

Interactive activity: Gently feel the shells. Are they sharp? They are very sharp! If you slip and get scratched by barnacles, you can get a nasty cut. So don't walk on rocks.

Thoughtful question: Can you guess what kind of animals barnacles are? Are they snails? Would you believe me if I told you they are like crabs?

NF#2: Barnacles are crustacea, like crabs and shrimps. Inside the shell is an animal with feathery legs. When the tide is high and the barnacle is submerged, the little doors on the shell open up and the feather legs stick out to gather bits of food. There's diagrams of what the barnacle looks like on the inside, in the Chek Jawa guidebook pg 50.
When it first comes out an egg, the barnacle larva looks like a tiny shrimp. When it finds a good place to settle down, the larva glues its head to the surface and builds a shell around itself. There a diagram of the shrimp-like larva in the Chek Jawa guidebook pg 49.

NF#3: Barnacles will grow on any hard surface immersed in seawater. Barnacles are even found on other animals such as whales and sea snakes. There are often even barnacles on top of other barnacles!

Corny joke: If you stayed long enough in seawater, barnacles will also grow on you!

Barnacles are considered a menace to the shipping industry as they grow on every ship. This reduces the speed of the ship and increases fuel consumption.

Too Much Information
Provide only if asked, or if you are desperately having to entertain a group while waiting for the tide to go down/rain to stop, etc.

Winner of the Most Manly Marinelife Award: Barnacles are usually hermaphrodites, each barnacle having both male and female reproductive organs. However, they don't self-fertilise. Instead, they fertilise neighbouring barnacles. As these animals cannot move, this is achieved by having tremendously long male organs! Some have an organ that can reach another barnacle 7 shells away!

Corny joke: This is like a husband 'doing' a neighbour's wife 7 apartments away!

In some species, a miniature male-only individual settles into the 'shell' of a larger member of its species. Reduced to little more than a sack of sperm, the male relies on its 'host' for protection and sometimes even food, in exchange for fertilisation services.

Human uses for barnacles:
The strong glue that barnacles use to cement themselves to the rock has been studied for use in dentistry for a similar protein cement to fit dentures. The glue has amazing properties: it hardens quickly under water and continues to work under pressure, in strong acids or alkalis and temperatures up to 225° C (440° F). The glue is so strong that even after the barnacle dies, its 'shell' stays stuck to the rock.

Are barnacles used to make oyster omelette or 'or luak'?
This is a common misconception. The ingredient in that dish is indeed oysters and NOT barnacles.

What are the different kinds of barnacles on our shores?

Star barnacle (Euraphia sp.) have star-shaped shells. About 0.5-1cm, sometimes seen, usually near the high water mark as they are tougher than the other bigger barnacles.

Acorn barnacle (Balanus sp.) have walls made up of plates. About 1cm, common, often found lower down on large boulders and hard surfaces.

Volcano barnacle (Tetraclita sp.) the walls are not made up of plates and has a ridged patten of bumps or short lines. The thick shell has an air-filled, honey-comb internal structure. This provides strength as well as insulation from the heat when exposed at low tide. (There is a photo of this structure in the Chek Jawa guidebook, pg 49)

Other barnacles include Goose barnacles (Lepas sp.) which is clam-like with thin shells made up of five white plates. A leathery stalk attaches the animal to a hard surface. These stalked barnacles grow on objects such as large logs that float in the open sea. These barnacles usually die once they are stranded on the beach.
The parasitic barnacle (Thompsonia sp.) grows through the body of the host crab like a root system. The parasite does not kill the crab but it does affect the crab's reproductive system such that the crab becomes infertile. The parasitic barnacle eventually produces egg sacs that emerge through the crab's joints, seen in the photo above. A crab infected by parasitic barnacles tends to be covered with seaweeds and other encrusting animals, including non-parasitic barnacles. It generally doesn't look very healthy.

Colonial Anemones: A Living Carpet!

2007-05-02T23:32:00.000+08:00

Three NAKED facts

Thoughtful question: Can you guess: are these plants or animals?

NF#1: They are animals and live in a colony: Each animal looks like a minature sea anemone with tiny tentacles on a long body. Each animal is joined to others nearby, sometimes by underground tubes. In some, the animals are embedded in a shared tissue so the entire colony looks like a rubber mat.

NF#2: Some may be highly toxic!

The most toxic marine poison, palytoxine, was discovered in a colonial anemone. A tiny amount of palytoxine can paralyse and even kill. So don't touch them! However, some animals can eat colonial anemones. These include the common hairy crab, filefishes and nudibranchs.

Corny joke: Some colonial anemones are colourful probably to warn of their toxic nature. You should avoid touching pretty and colourful marine life. Just like you shouldn't touch pretty girls!

NF#3: Their leathery skin is composed partly of chitin ("kai-tin"), the same substance that makes up the exoskeleton of insects.

Helpful hints for Naked Hermit Crabs ...

Where seen? There is a big patch of colonial anemones in the pool near the Tanjung Rimau beacon. You may also see them where the sandy beach ends and coral rubble begins, growing among the rubble. When they are out of water, they tuck their tentacles into their bodies and look like blobs of jelly or tiny sausages. Please don't step on them!!

Too Much Information!

Only for Naked Hermit Crabs who want to know Don't force feed this info to visitors! They may fall asleep if you do.

Colonial anemones are NOT sea anemones: Sea anemones belong to Order Actiniaria, while colonial anemones belong to belong Order Zoanthinaria. Thus colonial anemones are usually called zoanthids.

What are the different kinds of zoanthids?

Palythoa sp. don't have long body columns. Instead, the polyps are embedded in a shared tissue which may be strengthened by incorporating fine sand and other tiny debris. One study suggests these incorporated elements can make up 45% of the total weight of the colony! Some colonies can grow rapidly, nearly half a cm a day. They are quite aggressive and often overgrow surrounding animals.

Protopalythoa sp. have long body columns, have a wide oral disk and relatively short tapered tentacles, usually in two rows. The oral disk has furrows that radiate from the mouth to the edge of the disk. The polyps are not embedded in a thick common tissue but are joined to one another at the base by underground stems (called stolons).
Zoanthus sp. have a long body column with short, rounded (not tapered) tentacles, usually in two rows. Their distinguishing feature is a muscle surrounding the central mouth that makes the oral disk appear to be divided into two halves. The polyps are embedded in a thin common tissue that is usually hidden by sediments, or joined to one another at the bases by underground stems (called stolons). Sometimes, the individual polyps are so tightly packed that the polyp takes on a polygonal shape.
The zoanthids are currently under revision and classification of species may change.

What do they eat?
Zoanthids harbour symbiotic single-celled algae (called zooxanthallae) in their tentacles. The algae undergo photosynthesis to produce food from sunlight. The food produced is shared with the zoanthid, which in return provides the algae with shelter and minerals. It is the zooxanthallae often adds colour to the zoanthid.

Human uses for zoanthids
Palytoxin, the poison extracted from a zoanthid, has been used to better understand how our body works and may provide better treatment of hypertension, heart disease and other disorders. Zoanthids are also a popular item in the live aquarium trade, although their toxins make them dangerous to handle.

Hermit crabs and their friends

2007-05-02T15:49:00.000+08:00

Three NAKED Facts

NF#1: A hermit crab without a snail shell is a naked hermit crab!

Thoughtful question: How is the hermit crab different from the crabs you eat?

The crab you eat has its backside folded under its body and is protected by a hard shell.

A hermit crab looks like a cross between a crab (the front end of the hermit has hard claws and legs) and a shrimp (its backside is long and fleshy). The hermit crab's backside is soft and is not protected by a hard shell. (You can use the Naked Hermit Crab logo to show how the hermit crab looks without the shell. The diagram on the left is also in the Chek Jawa Guidebook.)

A hermit crab tucks its soft backside into an empty snail shell for protection. A naked hermit crab will soon be a dead hermit crab.

Please don't take any shells home with you. Hermit crabs need them more than you do!

NF#2: Don't pull the hermit crab out of its shell!

The hermit crab has little claws on its backside to cling onto the shell. If you try to pull the hermit crab out of its shell, it will cling desperately to the shell with these claws. So you may rip the hermit crab into two!

NF#3: Hermit crabs have many friends

Corny jokes: A hermit crab shell can get very crowded. If you were a hermit crab, you'll never be lonely!

The hermit crab makes such a comfortable home that other animals settle into the same shell. These include slipper snails, tiny porcelain crabs and small sea anemones.

Interactive activity: Let's try to find some of these friends on this hermit crab shell...

Thoughtful question: Why do you think living in the hermit crab's shell is so comfy?

The hermit crab creates a constant current of water. Friends get free air-conditioning.

The hermit crab is usually a messy eater. Friends get lots of free left-overs without having to look for food.

The hermit crab also moves around to find food, as well as to hide from danger. Friends enjoy all these by sticking with the hermit crab.

Corny joke: Living with a hermit crab is like living with your parents...

Another issue to explore...

Should we keep a hermit crab as a pet? Some reasons why we should not

Hermit crab friends that live on their shells need hermit crabs. If we remove the hermit crab, their friends will not have a place to live.

How much time will you spend with your hermit crab pet at home? 15 minutes, half an hour? Will you do this over many weeks, months? Or will you soon get bored and ignore your hermit crab pet?

Why not just spend that 15 minutes on the shore with a hermit crab? Here, the hermit crab is happy, doing its own thing, being with its friends. After you've spent time with it, leave the hermit crab behind in its natural home, while you go back to yours. You can always come back again to visit the hermit crabs on the sea shore.

Some tips on handling hermit crabs

To get the hermit crab to come out, you can try breathing on it, not blowing, just exhale (not sure why this works...perhaps it only works with MY bad breath :-). The surest way is to pour SOME (not the whole bottle of) freshwater into the shell.

Hermit crabs, especially big ones, can give a nasty pinch. Be careful.

Try to show tiny hermit crabs as well as big ones. To drive home the message that ALL shells should stay on the shore.

Too Much Information
Yes, the info is fascinating (especially to Naked Hermit Crabs). But if you tell them ALL to the visitors in one go they might faint from hermit overdose. Best to only share this if the visitors ask.

Does the hermit crab kill the snail to get its shell?
Hermit crabs never kill the original occupant of the shell. They may, however, quarrel with each other over a desirable shell. The hermit crab in this photo is patiently waiting for the small whelks to clean out the recently demised original occupant of the shell before trying on the empty shell.

What does a hermit crab eat?
Some hermit crabs are scavengers, i.e., they eat dead animals. These have a keen sense of smell to find their food. Others eat seaweed and muck (detritus).

Does the hermit crab always use the same kind of shell?
No. The same kind of hermit crab can use different kinds of shells. Even a tiny broken shell or an ugly shell covered with barnacles is a potential hermit crab home.

What happens when a hermit crab gets too big for its shell?
As a hermit crab grows bigger, it has to find a bigger shell. If the shell is too small, the hermit crab can't hide properly inside the shell from predators.

Corny joke: Hermit crabs understood the concept of 'upgrading' long before other Singaporeans!

Hermit crab musical shells: Before switching shells, a hermit crab will tentatively test out the new shell first, while holding on to the old one. If the new one is not ideal, it instantly goes back into the old shell. Often a whole group of hermit crabs will gather around a new empty shell. If the new shell is taken by a hermit crab, another hermit crab may take over the recently abandoned shell. And so on with the rest of the hermit crabs like musical chairs but with shells!

Are there any hermit crabs that can live without an empty snail shell?
The largest hermit crab in the world is the Robber or Coconut crab (Birgus latro). This hermit crab is so large that it no longer needs to live in an empty snail shell for protection. The Robber crab is only found in the Indian and Pacific Ocean islands. It is not found in Singapore.

What are the different kinds of hermit crabs on Singapore's shores?

The Striped-hermit crab (Clibanarius sp.) has stripes along its legs. It is usually orange, but sometimes, blue or even dark green ones may be seen. Its pincers are of equal size. It is more commonly seen on our Northern shores.

The Tidal hermit crab (Diogenes sp.) is drab and has one pincer that is much bigger than the other.

The Land hermit crab (Coenobita cavipes) has squarish legs and pincers and is usually a shade of violet. It is usually found only on undisturbed shores, near the high water mark and is more active at night or near sunset or sunrise.

Tiny hermits Piles of tiny shells of different kinds are often encountered on a stone at low tide. These are usually homes to tiny hairy hermit crabs. Almost all our shores have these hermit crabs.

Hermits with no name I have yet to find out the identity of these two different kinds of small hermit crabs. They are commonly seen on good reefs and coral rubble. I have seen both on Sentosa.

Horseshoe crab: Ancient Armoured Animal

2007-05-01T19:25:00.000+08:00

Three NAKED facts

NF#1: Ancient animal The horseshoe crab is a strange, ancient creature that has been around since before the dinosaurs. It is NOT a crab or even a crustacean. It is more closely related to spiders and scorpions. Its interesting body parts are under the shell. It has different kinds of legs: for walking, picking up food, cleaning itself. The flaps near the tail are book gills.
NF#2: They do NOT use their tails to sting people. The sharp tail is not venomous and is not used as a weapon. It is merely used as a lever to right itself if it is overturned. The tail is also used as a rudder when moving underwater.

If a horseshoe loses its tail, it is doomed. So please don't dangle a horseshoe crab by its tail.

NF#3: It is threatened! The horseshoe crab is listed among the threatened animals of Singapore due to habitat loss. It's a pity that something that survived for so many millions of years can be wiped out by humans.

Hints to Naked Hermit Crabs
Horseshoe crabs are sometimes buried in the ground. Look for tell-tale lumps or the tail sticking out.

They are often seen in the pairs. The male is the one on top. Please don't separate them. The male usually clings on very tightly.

If you have to lift up a horseshoe crab, hold the sides. Don't hold it up by the tail.

Be careful of the tail. It may twirl around and may poke a child's eye out if you are not careful. It is best NOT to lift the horseshoe crab and just look at it on the ground/in the water.

If you have to turn it upside down, do it for a short while only and help it to turn back around.

WAY Too Much Information
Horseshoe crabs are fascinating, but ordinary people usually can't take a full dose of horseshoe crab info at one go.

Two kinds of horseshoe crabs are found in Singapore. The Coastal horseshoe crab (Tachypleus gigas) is more often encountered on the Southern shores. It is large (diameter 25cm) tends to be greyish and has a tail with a triangular cross-section. The Mangrove horseshoe crab (Carcinoscopius rotundicauda) is smaller (diameter 15cm), tends to be more brownish and has a tail with a round cross-section.

The horseshoe's exoskeleton, unlike a crab's, does not incorporate calcium and is made of chitin and protein instead. Sometimes, you might come across what appears to be dead horseshoe crabs on the shore. These might just be moults. Moults are lightweight, have transparent eyes and no bad smell.

What does it eat? A harmless creature, the horseshoe crab bulldozes quietly along on the sea bottom feeding on worms, clams and anything edible including dead animals. They may also scrape off algae.

Eating with its legs! The horseshoe crab has no jaws. It has to grind down its food with the rough spiny areas (called gnathobases) near the base of the walking legs. The first pair of legs are tiny with small pincers which pick up and pass titbits into its four pairs of 'food processing' legs. Walking movements grinds up the food and the bits flow into the mouth, which is between the second pair of legs and conveniently faces backwards. So a horseshoe crab can only eat while it walks! In fact, the Class it belongs to is called Merostomata, which means 'thigh mouth'.

Galloping Horses? Horseshoes generally creep slowly over the sea bottom. However, they can move more speedily if they have to. They can use their last pair of legs, called pushers, to lurch forwards. These legs are longer, have spines which flare out when pushed against the sand. These legs are also toothed, and thought to direct water flow over the gills and to clean the gills. Horseshoe crabs can also swim for short distances, using their swimmerettes and gill flaps. They can also 'hop' over the sand slowly by bending their hinged body then pushing forwards against the tail, which is anchored in the sand.

Super gills: Horseshoes breathe well in oxygen-poor water. They have five pairs of flap-like appendages which contain book gills.

Blue blood: Horseshoe crab blood contains copper compounds which carry oxygen, the way iron does in our blood. So horseshoe crab blood is blue when exposed to air! But the horseshoe crab is NOT the only blue-blooded arthropod. Some true crabs and other arthropods also have blue blood.

Reproduction: Horseshoes mate during high spring tides when they can reach the highest part of the beach. The males are smaller and usually hitch a ride on the females using their specially adapted hooked first legs. The female digs a pit near the high water mark and lays her eggs. The males release sperm over the eggs and the nest is covered.

Eggs hatch at the next full moon when the tide is at its highest again. The hatchlings (called trilobite larvae) look like miniature adults but without tails, and are bright green! The larvae burrow into the sand and after a few moults begins to develop tails.

Human uses: Horseshoe crab blood has a substance that is so sensitive to bacteria that purified extracts of the blood are used to test for the presence of bacteria in human medication (e.g., intravenous fluids) and in medical tests. About 200,000 crabs are bled every year for this substance. About 20% of a horseshoe's blood is extracted and in the US, laws require that the animal be returned to the sea. But about 10% die in the process. A team from the National University of Singapore's Department of Zoology has cloned a substance to replace wild-extracted horseshoe blood.

Horseshoe crabs have also contributed in other ways to human health. Much of the basic principles of vision is based on studies of the horseshoe crab's eyes.

A load of Crabs!

2007-05-01T19:20:00.000+08:00

NAKED facts about some crabs you are likely to come across

Rocky shore crabs
Commonly seen on Sentosa's rocky shores are the Red-eyed reef crab (Eriphia smithi) left and the Purple climber crab (Metopograpsus sp.) right. But they are usually only active at night. They have sharp pointy claws on their legs to grip slippery rocks.

Teddybears of the shore
Hairy crabs (Pilumnus sp.) are quite common among coral rubble. They have a coat of silky hairs all over their bodies and legs. In the water, these fluff up and trap sediments, camouflaging them perfectly.
Eggs NOT for eating!
The Red egg crab (Atergatis integerrimus) on the left is more commonly seen than the Brown egg crab (Atergatis floridus) on the right. In fact the Brown egg crab is listed among the threatened animals of Singapore. Both crabs are highly poisonous and contain toxins which are not destroyed by cooking. Since other animals don't particularly want to eat this crab, it is slow moving and doesn't really bother to hide.
Swimming crabs (Family Portunidae)
These often colourful crabs have paddle-shaped last legs. These legs rotate like boat propellers allowing the crabs to swim quite fast. They have long pincers to snag fast moving prey like fish.

Hints for Naked Hermit Crabs
Crabs PINCH! And some can pinch hard enough to draw blood. Don't touch them.

Snapping shrimps: Pop musicians of the shores

2007-05-01T19:15:00.000+08:00

Two NAKED facts

Thoughtful question: Can you hear the little pops and snaps? Can you guess what causes those sounds? Can you guess how big the animal is?

It's made by a tiny shrimp that lives in burrows and under stones!

NF#1: Sound blaster pincers: A snapping shrimp has one of its pincers greatly enlarged. This pincer may even be as long as its entire body! The pincer has a moveable 'finger' held apart with a catch. When the catch is released, an explosive sound results.

The blast stuns prey like tiny fish and cracks the shells of small clams. It is also used to ward off predators and intimidate rival pistol prawns.

NF#2: Shrimpy friends: The shrimp goby lives in the same burrow with a snapping shrimp. With keener eyesight, the goby keeps a look-out while the shrimp busily digs out and maintains their shared home. The shrimp is literally constantly in touch with the goby with at least one of its antennae always on the goby. When the goby darts into the burrow, the shrimp is right behind it!Too Much Information

The Science of The Sound: The snapping sound is not made by the fingers actually hitting each other. Rather, a high-speed jet of water shoots out due to the extremely rapid compression of the fingers. This jet vapourises the water and creates a bubble. When the bubble collapses, the sound results. Not only that, a flash of light is also emitted!

These findings are possibly useful for naval applications as the sound of snapping shrimps seriously interfere with sonar detection in shallow seas. In fact, snapping shrimps have been studied since World War II as their sounds interfered with the detection of hostile submarines!

More snapping friends: Snapping shrimps also live in symbiosis with other animals such as corals, sponges and sea fans. The tiny (1cm) Crinoid snapping shrimp (Synalpheus stimpsoni) lives in pairs on feather stars (crinoids), feeding off the mucus of its host. It is listed among the threatened animals of Singapore.

Two snapping shrimps commonly seen on our shores...

One is smaller 4-6cm with a rounded pincer often with an orange 'finger'The other is larger 5-7cm with flattened pincers.

Shrimps and Prawns: Do we know where they come from?

2007-05-01T19:10:00.000+08:00

One NAKED fact

Question: Do you like to eat prawns and shrimps? Do you know their life cycle?

NF#1: Prawn nursery: Most adult shrimps migrate to deeper waters to breed and release their eggs. Eggs usually hatch quickly, within a day or so. After hatching from the egg, the larvae look nothing like the adults! These larvae drift with the plankton, changing shape as they develop further. Eventually, they look more shrimp-like and migrate back to shallow waters. Here they develop into mature adults before starting the cycle all over again.

The following is a rather depressing approach to shrimps and prawns...
but this helps people understand the ecological cost of our seafood

Prawn farming is destructive: The large prawns that we eat often come from prawn farms or are harvested from the wild by trawling or traps. While traditional farming and harvesting methods are sustainable, large-scale commercial prawn farms and prawn trawling are more destructive and unsustainable.

Commercial prawn farming often involves:

Destroying large tracks of mangroves and other intertidal habitats to create the farms;
Harvesting egg-bearing adults from the wild to provide stock for the farms;
Introducing non-native prawns which could upset the natural balance if they escape;
Adding chemicals to the water to prevent diseases or boost growth. These affect surrounding wildlife;
Releasing large amounts of waste water from the farms that poison the surrounding habitats; and
Saltwater from the ponds eventually seep into groundwater and affects supplies of freshwater to humans and wildlife in surrounding areas.

Large-scale trawling often involves:

Dragging large heavy nets repeatedly over shallow areas. This damages everything on the sea bottom. Recovery of the habitat can take 1-20 years.
An enormous waste: commercially valuable prawns often make up only 10% of what is caught, the rest is thrown back often dead.

The destruction of mangroves for shrimp farming is believed to have aggravated the impact of the Indian Ocean Tsunami of Dec 04.

Some shrimps and prawns that may be encountered on Sentosa
Larger prawns are usually only active at night. During the day, some bury themselves in sand. Others hide elsewhere.Tiny shrimps are commonly seen all over the shore; among seaweeds, on corals, just on the bottom of shallow pools. Some have a red 'nose'.

House Rules for scribbling on the Home Shell

2007-05-01T19:08:00.000+08:00

Dear fellow Naked Hermit Crabs,

We have specially built the Home Shell to share nature facts and guiding tips for our walks.

If you have anything interesting to add to an entry, just make a comment to it!

We welcome sharing of information and will be glad if you add an entry. But please do read the following guidelines before doing so.

House Rules for Scribbling on the Home Shell

It's all about getting naked - less is MORE!

Please don't be long-winded. Go straight to the point.
No flowery language and difficult words.

Share only THREE facts that would be interesting to ordinary people. Ordinary people tend to be intrigued by

Sex
Violence: catching prey, escaping from predators
Features or behaviour that are disgusting, funny or weird
How it contributes to our daily lives (e.g., can eat or not?).

Share interesting ways to present the information/lifeform:

Questions that encourage thought, closer observation;
Things to do: smell, feel, taste, hear, see
Include at least one corny joke!

Share useful tips on how to find the lifeform, and how not to/to handle it.

It will be great if your three facts can bring across the core CRAB messages

Care Inspire visitors to care for nature. We must be careful when visiting nature places and minimise the damage. The shores are fragile and animals are delicate.
React Encourage reaction and participation from visitors. Make them feel for and interact with the shore.
Appreciate Highlight why we should appreciate nature, what it offers us, and why we should conserve it.
Balance There should be a balance between nature and development. Conservation does not mean anti-development. There are ways to work around the problems, and nature can also complement development.

Include one or two photos to illustrate your point, but not too many please.

Photo specs: max 400 pixels across. This is to keep the site fast loading and to avoid messing up the layout.

In addition to the THREE naked facts, if you have additional information that is interesting for other Naked Hermit Crabs to know AS BACKGROUND, you can include it under a heading Too Much Information. This information should not be force-fed to visitors unless you want them to go into a coma.

You may include links to more information (pls choose reliable sources yah?) and keep the link list short.

The moderators may amend your entries and photos so that they meet the guidelines.

The moderators may also manage the labels of your entries.

If you are posting for the first time, please look at the other scribbles for reference.

Thanks :)