Saturday, May 02, 2009

Chek Jawa Walk on 2 May

Today, I was back again at Chek Jawa to guide for the public walk. The weather was really great, and I was really looking forward to seeing all kinds of interesting stuff!

This was the group that I guided. They were residents of Braddell Heights, making them my neighbours!

Stick Insect (Order Phasmatodea)
The first animal we saw was this Stick Insect (Order Phasmatodea), which could camouflage itself very well, looking just like a twig!

We had to climb down a ladder to reach the intertidal area.

Sand Collar
This is a Sand Collar. It is the egg mass of the Moon Snail.

Haddon's Carpet Anemones (Stichodactyla haddoni)
We saw quite a few Haddon's Carpet Anemones (Stichodactyla haddoni) on the sand bar. During low tide, this anemone will retract its oral disc to try to retain water, so that it will not be dehydrated.

Flower Crabs (Portunus pelagicus)
Like other crabs, Flower Crabs (Portunus pelagicus) have to moult in order to grow bigger. The above are the shed shell of a female (left) and male crab.

Clams are very common at Chek Jawa. Being filter feeders that filter for plankton in the water, they will close their shell tightly during low tide to prevent themselves from drying out.

Sand Dollars (Arachnoides placenta)
Sand Dollars (Arachnoides placenta) were quite abundant. They feed on algae, and their mouths are located on the underside.

Watering Pot Shell (Brechites penis)
The highlight of the day was this Watering Pot Shell (Brechites penis) that I spotted among the seagrass. This was my first time seeing it in the wild!

Watering Pot Shell (Brechites penis)
It is a bivalve, but the two valves are greatly reduced and are fused onto the walls of the calcareous tube. Like most clams, it is also a filter feeder.

Orange-striped Hermit Crab (Clibanarius infraspinatus)
Our hunter-seekers found us this Orange-striped Hermit Crab (Clibanarius infraspinatus). Despite the common name, hermit crabs are not true crabs. They have a soft and long abdomen, and thus need to tuck it into an empty shell to protect it.

Sea Cucumber
This unidentified sea cucumber is a good burrower. I often see it half buried under the sand.

Sandfish Sea Cucumber (Holothuria scabra)
Also a good burrower, the Sandfish Sea Cucumber (Holothuria scabra) is the one that we can commonly found served as a delicacy in Chinese restaurants. They are actually toxic though, and thus need to be properly treated before they can be consumed.

Noble Volute (Cymbiola nobilis)
The Noble Volute (Cymbiola nobilis) is again a good burrower. It feeds on other snails and clams by embracing them in its huge foot to try to suffocate them. When the prey opens up to breathe, the volute will feed on it. Somehow, the one above reminded me of a submarine when it slowly burrowed into the wet sand.

Cake Sea Star (Anthenea aspera)
Thanks to our hunter-seekers, the visitors got to see this pretty pink Cake Sea Star (Anthenea aspera)!

Sand-sifting Sea Star (Archaster typicus)
I was glad to see this Sand-sifting Sea Star (Archaster typicus). This sea star can burrow to escape from predator and also to seek food. They feed on tiny organic particles in the the sand.

Sand Star (Astropecten sp.)
This Sand Star (Astropecten sp.) is a fierce predator of small clams and snails.

Mangrove Horseshoe Crab (Carcinoscorpius rotundicauda)
The past few times I saw Mangrove Horseshoe Crabs (Carcinoscorpius rotundicauda) at Chek Jawa, they were all very small ones. So finally today, I got to see an adult! Horseshoe crabs are living fossils which existed for more than 400 million years.

Geographic Sea Hare (Syphonota geographica)
The Geographic Sea Hare (Syphonota geographica) appeared to be in season, and we saw a number of them. These sea slugs were said to feed on algae.

Here's a group shot taken near the water's edge.

Acorn Worm (Class Enteropneusta)
This coil of sand is the cast made by an Acorn Worm (Class Enteropneusta). It feeds on tiny organic particles in the sand by swallowing the sand and process the edible bits. The remaining sand is pushed out of its backend, forming the cast.

Sand Bubbler Crab (Scopimera sp.)
There were lots of sand balls on the sand bar made by Sand Bubbler Crabs (Scopimera sp.). This crab feeds on tiny organic particles on the sand. As they extract the food particles, the processed sand was discarded in the form of small sand balls.

Sentinel Crab (Macrophthalmus sp.)
This Sentinel Crab (Macrophthalmus sp.) was found by Adelle's group. It has long eyestalks which enable them to see predators from afar, so that they can quickly burrow into the sand. When they burrow, the eyestalks will be folded down nicely into the slots located beside them.

Soon, we had to leave the intertidal area, and our brave ladies had no problem climbing up the steep ladder!

Nipah Palms (Nypa fruticans)
We decided to head towards the mangrove boardwalk on our way back. There were lots of Nipah Palms (Nypa fruticans) by the sides of the boardwalk. These palm trees always remind me of my childhood days, when I lived in an attap house with its roof made from Nipah leaves, otherwise also known as attap leaves!

Mangrove Cannonball (Xylocarpus granatum)
The Mangrove Cannonball (Xylocarpus granatum) fruit that I saw when I was here a few weeks ago was still attached to the tree! This tree got its common name from the big and round fruit.

Malayan Water Monitor (Varanus salvator)
A juvenile Malayan Water Monitor (Varanus salvator) just under the boardwalk went running towards the mangrove trees when we walk by. Being mildly venomous, scientists believe that monitor lizards are probably closely related to snakes.

Tumu Putih (Bruguiera sexangula)
We went to check out the Tumu Putih (Bruguiera sexangula) planted by Nparks. So far, the few wild trees in Singapore can only be found at Pulau Tekong.

Tree-climbing Crab (Episesarma sp.)
We also saw several Tree-climbing Crabs (Episesarma sp.) resting on the mud lobster mounds while walking along the boardwalk. These crabs are also called vinegar crabs, as they are sometimes pickled in vinegar by the Teochews, and eaten with porridge.

Painted Bronzeback (Dendrelaphis pictus)
Towards the end of the boardwalk, we even spotted a Painted Bronzeback (Dendrelaphis pictus). It got their common name from the bronze colour on its back.

I was really glad that we had so many exciting sightings today, thanks to our excellent hunter-seekers and sharp-eyed visitors!


Anonymous said...

Hi... im interested in the walk... look interesting with so many things to see.... care to share the schedule for the walk?


Aryaman Stefan Wellershaus said...

- friends, in your very impressive collection of photos of sea animals you have a nice photo of Macrophthalmus spec.

Recently I have published a blogged record on the zoeal development of some Macrophthalmus in the Red Sea - at least I believe it is M. The address of the blog is . I would like to add your photo to this blog. I shall do it, and if you have any objections please let me know.

With greetings from the wintery Baltic Sea yours Stefan Wellershaus.

tHE tiDE cHAsER said...

Hi Stefan, thanks for visiting my blog. Sure, please go ahead and use the photo.