Sunday, January 20, 2008

Chek Jawa Walk on 20 Jan 2008

Finally had my first guided walk of the year!

Guided at Chek Jawa for Nparks today, and with me were people from MND. We saw lots of interesting stuff, and guess I'll just highlight some of them today in this entry :)

And here's the gang at the top of the Jejawi Tower. Named after the nearby jejawi tree (also known as the Malayan banyan), the tower is about 20m tall, and gives a great view of the surrounding area.

After getting down from the tower, we entered the mangrove area, with swaying nipah palms (Nypa fruticans) growing on both sides of the boardwalk. We were quite lucky that one of the palm was flowering. Nipah palm, otherwise also called attap palm, is where you get your attap chee in your ice kacang from. During my kampong days, I used to live in an attap house which has a roof made from attap leaves :)

One sure sign that you are in a mangrove is when you see all these trees with exposed roots. The roots above belongs to the bakau trees (Rhizophora spp.). As the soil in a mangrove is usually very lacking in oxygen, mangrove trees adapt to this condition by having their roots exposed so as to take in oxygen from the air!

Near the end of the 500m-long mangrove boardwalk, we suddenly realised that we've entered crab territory. Hundreds of fiddler crabs (Uca spp.) were there waving their claws! And mind you, actually only the males have an enlarged claw. This claw is used to attract females, and also to intimidate other males.

Somehow we seem to have a lot of luck with elbow crabs (Family Parthenopidae) today. I saw at least five of them, despite that fact that they were usually so well camouflaged! Now, can you guess why they are called elbow crab? Just take a look at the pincers...

Several of my visitors were quite delighted to see the gong gongs (Laevistrombus canarium) in their natural habitat.

And of course, another familiar edible shell is the razor clam (Family Pharidae). Found it trying to burrow into the sand.

After the few days of heavy rainfall, I was quite relieved to see the resident carpet anemone (Stichodactyla haddoni)looking rather healthy. Hopefully we won't get another round of ultra heavy rainfall resulting in another mass death again...

Carpet anemones have sticky tentacles which trap animals that got too close to it. The tentacles has stinging cells that fire toxins into the animals to kill them. Acting like a conveyor belt system, the tentacles will also move the prey to the middle of the anemone, where the mouth is.

Found this sea cucumber again. Still, have no idea what species it is. Do you know that unlike us, sea cucumbers actually breathe through their backends?

As usual, there were lots of sand dollars (Arachnoides placenta) at the sand bar. They got their name because they look like coins.

And our first star of the day was this sand star (Astropecten sp.)! Quite surprised to see so many of them out so early, as most of the time they hide under the sand on a hot and bright day like this, and surface when it gets cooler and darker.

We were also quite fortunate that our hunter-seekers found us a seahorse (Hippocampus sp.) today!

Found a lot of these orange beehoon-like things among the seagrasses and seaweeds. These are sea hare eggs, and so I was expecting to see one of them along the way.

And indeed, we found a few hairy sea hares (Bursatella leachii)! Sea hares are basically snails with soft internal shells.

We also saw this sea star above, which for some time some of the guides had been wondering whether it's a juvenile cake sea star (Anthenea aspera) or a Gymnanthenea laevis, since it has the identifying features shared by both species. Personally I had thought it looked more like a cake sea star from its shape.

This time round, I finally remembered to take some close-ups of its upper surface to check for another identifying feature of a cake sea star that G. laevis lacks.

While it's not exactly super obvious, I was able to find some bivalved pedicellariae (those circled in red) on its top surface, and bigger versions were also present on its underside. Thus according to the "Guide to Sea Stars and Other Echinoderms of Singapore", this is most probably a juvenile cake sea star.

The hunter-seekers found two of these worms. Really have no idea what they are too. Hopefully some experts out there can answer me. They certainly didn't look like segmented worms to me, when another friend suggested that.

Yet another star find - a brittle star (Order Ophiuroidea)! And like its name, it is very brittle and its arms break off easily, so please handle it with care... Fortunately, they are able to regrow their broken arms though, but in the meantime, they will be at a disadvantage dealing with their everyday life with fewer arms.

And just before we got out of the intertidal area, we had a pleasant surprise of finding this cute little pink warty sea cucumber (Cercodemas anceps) hiding among some shells among the seaweeds!

After the walk at the jetty, we were given another treat from nature, with a few beams of sunlight peeping through the clouds, illuminating some boats in the distance.

What a way to end the day! Will be back at Chek Jawa to help KS on his project on Tuesday. Sure looking forward to see more great stuff!


Joe Lai said...

Wonderful to see the beehoon thingy you identified as belonging to the sea-hares. I remembered seeing so many of them on my first few explores of Chek Jawa many many years ago.

Keep up the good work guiding! Well done!

Ron Yeo said...

Thanks for your comments, Joe :)