A visit to the brave Chek Jawa

I visited Chek Jawa a decade ago for the first time, after signing up for a guided walk by NEA. While memories of that trip have since been archived, I still vividly recall images of troops of male Fiddler Crabs waving their enlarged pincer at each other/ me, as if saying hi and waving goodbye. I also remember being amazed by my first encounter with the rich biodiversity that I never knew existed in Singapore.

A decade later, I return to this wetland treasure on 19 Dec, feeling a little foreign. The area seems more barren, just... not as lively as before.

Apparently, persistent drastic rainfall over a few weeks in 2007 brought flood waters into the Johor Straits, resulting in Chek Jawa being flooded with lots of freshwater. The marine animals didnt survive the ordeal then. However, it is hearty to hear that the Chek Jawa I saw on 19 Dec was one who is trying its might to nurse back its health.


My first Sea-Star of the day was the Sand-sifting Sea Star (Archaster typicus) aka the Common Sea Star. This Sea Star for its name from its action of burrowing into the sand to feed on organic detritus or escape from its predators. It uses its tube feet found on its underside to move around, and to bring food to its mouth, 2-in-1 use, how very efficient!

A tiny pink 'dot' stood out amongst the sea of brown and green (seagrass and algae), literally 万绿从中一点红. This Pink Thorny Sea Cucumber (Colochirus quadrangularis) is no longer than my index finger. In water, one can often see tts feeding tentacles at one of its end lashing around in water to collect very tiny particles in the water for food.

Its always a 50-50 guess when I come across any shells on the shore. As I quietly wish to myself for a Noble Volute, I turn this shell around and saw its occupant, the Orange Striped Hermit Crab (Clibanarius infraspinatus) instead. Unlike true crabs, Hermit Crabs have a soft abdomen, and occupy shells for protection. Therefore it is important that we do not bring shells, even broken ones, home because it can be a potential shelter for the Hermit Crab!  It uses its last pair of legs to 'carry' the shell, and I often wonder whether if it feels tired carrying its house around - guess they can always stop to take a rest.

Another animal that burrows into the sand is the Sandfish Sea Cucumber (Holothuria scabra). If you find this animal very 眼熟 (familiar), you probably have seen this at your dining table (although it typically doesnt look this way after being cooked). This is the species of Sea Cucumber that some Chinese deemed as a delicacy. Do note that it requires some processing before it is edible as it is mildly poisonous.

Another regular item one can see at the barbeque stall at food centres - the Gong Gong (Strombus turturella). The small brown feature that is sticking out as seen in the middle of the picture is its operculum, which acts as a trap door. It is also used by the Gong Gong to push itself against the substrate to leap away. The Gong Gong is fairly abundant on our shores, but I cant quite imagine how one will bear to eat it after seeing its 2 very cute eyes.

I was initially excited to see a Tube Anemone (Order Ceriantharia) thinking that they are hard to come by since many anemones died during the flash flood. This excitement soon wean off because I realised there are quite many of them! I'm not complaining because this is a good sign of recovery! The Tube Anemone got its name because of its home - a tube made up of mucus and sand! How very green of them to recycle existing materials.. =)

I was hoping to find a Key-Hole Sand Dollar which is uncommon and is on our Red Data Book, but instead, saw several of the Arachnoides placenta (also Sand Dollar, but difference species). Resembling a dollar coin, this is a flat cousin of the Sea Star which has very short and tiny spines that help it 'walk'.

The second Sea Star of the day was the Sand Star (Astropecten sp.), a predator that eats small clams and snails. These 2 that I saw were moving towards each other from opposite directions, once they meet, they stopped for a brief moment and the left one started to follow the other around for a while before spliting up again eventually. I imagine them to be old friends bumping into each other after a long while and stopped to catch up before parting ways - although this wouldnt be possible because they do not have a brain!

This time round, its the real incumbent - the Noble Volute (Cymbiola nobilis) that I saw. This was the largest that I've ever seen, maybe 20 cm in length, and its laying eggs! Another good sign of a recovering Chek Jawa since the environment proves to be conducive and suitable for reproduction. Naturally, its pretty shell resulted in an over-collection of its shells by human beings and in some areas, it is also collected for food! =(

I peered into a small crevice by one of the pillars and was lucky enough to see a Wandering Cowrie (Cypraea errones). Shells of this snail were said to be used as currencies long long ago, thankfully this is not the case now else they would have been extinct ! Not well portrayed in this photo, the Cowrie actually uses its mantle to cover its shell. This helps to keep the surface scratch-free and pretty, just like the effect of our face masks!

Someone found this Mantis Shrimp and managed to hold it in a container for us to take a closer look (it was of coures released after a while). A predator , the Mantis Shrimp uses its claws (with sharp spines) to catch other animals such as small fishes for food. It got its common name probably due to its resemblance of both a praying mantis (the 2 claws) and a shrimp (body).

As usual, I was happy to see another Sea Star! This one is a Biscuit Sea Star (Goniodiscaster scaber), unfortunately I only managed a blurred photo (as you can tell from now that my photography skills clearly needs some brushing up). Some say this Sea Star got its name because of its resembance to a biscuit, but I take more to the reason that its sides are smooth and shape regular, as if everyone of them is cut out from a biscuit cutter.

This Sea Star is also a Sand Star that I saw earlier, but instead of 5 arms, it has 6! Sea Stars are often depicted as having 5 arms, little do most people realised that they can have 4 arms or 6 arms or more!

My last discovery of the day before we head back to the visitor centre was this Moon Snail. Looks like a Tiger Moon Snail (Natica tigrina) to me. Didnt get a clearer view of the shell as I didnt want to disturb it since it looked like it was hunting for food. Moon Snails are more active at night and are fierce predators that feeds on other snails and bivalves and suffocates its prey with its huge body. If this fails, it secretes an acid to soften the prey's shell patiently, before creating a hole and inserting its radula (tongue-like feature) to feed!

Although affected by the flash flood, Chek Jawa still has quite a fair bit of marine life to offer. Hopefully she will return to her glory days in no time!