Sunday, September 21, 2008

Discovery @ Changi Beach on 20 Sep 2008

Seventy Fourth Discovery Posting:

Finally, the wait is over. The lower low tides of the day are finally here! And this means that I don't have to wake up at wee hours of the morning. =P

Yesterday late evening, with the company of E, G and I, we went on a exploration trip to Changi beach.

The first 'discovery' was a cool find. A flatfish (picture below)!
Discovery Note:
1. When a flatfish first hatches, it is a sole larve which looks like a larve of other 'normal' fish.
2. As the larva matures, it starts to swim on one side of its body, and one eyes and the mouth move to the upperside. This change may be completed within a span of five days.
3. It is interesting to note that the skeleton and digestive system also changes as the larva matures.
4. Once it is matured, the eyed-side (upperside) has camouflaging colours and patterns (as seen in the picture above) while the blind side (underside) tends to be paler.
5. The flatfish in its adult stage is an ambush predator. It usually lies in ambush just beneath the sediment or sand, with only its eyes sticking out waiting to snap up any small bottom-dwelling worms, bivalves, crabs and prawns which passes its ambush spot.
6. Information retrieved from You may also read more about the flatfish on the same website.

The second 'discovery' of the night was a gong gong (picture below).
Discovery Note:
1. In Singapore, the gong-gong is a popular dish which is eaten steamed, fried with chilli or as fritters.
2. However, they are now uncommonly seen due to overcollection and habitat lost.
3. Interestingly, the gong=gong moves like a pole-vaulter.
4. It uses its claw-like operculum (as seen above) to dig into the substrate and pushes against it to 'hop' itself around.
5. Interestingly, they have a pair of eyes on stalks(as seen above) to help it see where it is and going.
6. Information retrieved from You may also read more about the gong gong on the same website.

Walking around, we also managed to spot a few sea pens, here's one of them (picture below). Third 'discovery'.
Discovery Note:
1. Sea pens belong to the same group as soft corals and like soft corals, they are a group of polyps connected to one another in a colony.
2. While the polyps on hard/soft corals are alike, in a sea pen, there are different types of polyps connected to each other, each playing a different role.
3. First, there is the primary polyp, a central stalk which supports the whole colony. One role of the primary polyp (the bottom half) is anchoring the whole colony to the substrate and retracting the whole colony into the ground at low ride. It is interesting to note that the primary polyp is one individual animal.
4. Other individual animals emerge from the upper half of the primary polyp forming the 'feathers' on the central stalk. These are called secondary polyps or autozooids, they have stinging tenacles that filter feed when underwater.
5. There is also another kind of polyp, which is highly modified, called siphonozooids. Their role includes pumping water into the colony to keep it rigid and circulate water through the colony.
6. Information retrieved from You may also read more about the sea pen from the same website.

Now fourth 'discovery' is something which I am not sure of its exact ID. But it looks a lot like a sea cucumber...hmm... can anyone help me with this (picture below)?
Discovery Note:
1. We spotted a number of them around buried amongst the seagrass. So they could be in season.

As we walked around, I lamented on why were there no sea stars, and as if hearing my complains, they soon pop out...hahaha.

Fifth 'discovery' is sand stars (picture below).
Discovery Note:
1. Sand stars, as the name suggest, are more often seen in sandy pools or sand banks.
2. They tend to be more active during night time while remaining buried in the sand during the day.
3. Sand stars have particularly long spines on the sides of their arms. These spines are harmless.
4. Sand stars are generally fast moving, in fact, one of the fastest moving seastar I have seen.
5. Unlike other sea stars which push out their stomachs to feed, they are one of the few species of sea stars whom swallow their prey whole.
6. They are known to be carnivores, their diet consists of bivales, snails and any small creatures which are in the sand.
7. Information retrieved from You may also read more about the sea pen from the same website.

Sixth 'discovery' seems to be a biscuit star (picture below). I could not confirm its ID as I did not manage to get a good close up photo of its oral side.
The last organism which we took a load of time photographing was this stripped hermit crab (picture below). Seventh 'discovery'.Discovery Note:
1. Hermit crabs are not true crabs. What do I mean by that? Read on to find out...
2. True crabs have a hard, shorten abdomen which they fold under their hard shells (carapace) for protection.
3. Hermit crabs, on the other hand hand, have a soft, long abdomen and they don't have a hard shell to fold it under. So they insert and twist their abdomen into an empty shell for protection. So do not pull hermit crabs out their shells as you may tear its soft abdomen.
4. As a hermit crab grows bigger, its abdomen also grows bigger and it will have to find a bigger shell to accomdate this growth, or in other words, they 'upgrade' their 'homes', just like Singaporeans do.
5. The above point highlights the reason why we shouldn't pick seashells from the seashore like Sally =P.
6. Information retrieved from You may also read more about the hermit crab in general from the same website.

Overall, it was an enjoyable night due to the many marine life seen, the sharing and company of friends and a walk under the stars. =)