Jul 2, 2008

Pasir Ris: some mysterious finds

3am and Chay Hoon and I decide to check out the rest of the large Pasir Ris shore. There's larger patches of seagrasses there!The shores are rather soft, but teeming with life. In the rather clear waters of this last of the morning super low tides, there are swimming crabs, sea stars and hermit crabs.Lots of hermit crabs! In huddles here and there. Hmm, I wonder what they're up to?

And a super abundance of sand stars (Astropecten sp.).
In various sizes from tiny to large.For some reason, I saw a lot of them upside down today. I also saw the remains of a disintegrated star. Was it attacked? Or is something else happening to them? There were also many with lost arms, like this poor star with three regenerating arms.

The masses of black short-spined sea urchins (Temnopleurus sp.) was seen again.These sea urchins 'carry' stuff like shells, which is why there are so many clam shells among the sea urchins. I'm not sure why they gather in groups like this. They seem rather smaller than usual for it to be for mating. Possibly for protection?

A mystery echinoderm was this purplish sea cucumber in the middle of the sand flat.I have no idea what it is.

And a mystery fish!It has a very long first dorsal fin and pretty colours on the tail and the rest of the dorsal fin. I tried to take a closer look at it but the fish disappeared into a burrow as soon as I approached.

There were also several of these large beautiful shells on the shore.The shells are empty. I have no idea what kind of snail made this shell and where they live. In deeper water? Burrowing in the sand?

Another puzzle were these clumps of bubbles on the sand. Several were seen, like delicate glass ornaments.

Another glassy marvel is this beautiful sea anemone which I call the glass anemone because it reminds me of blown glass.It's also sometimes seen on our other northern shores. It is one of our common sea anemones that have yet to be identified.

This soft shore is full of all kinds of different anemones. Including this odd little dark anemone that I've not seen before.
A closer look reveals rows of bumps along the body column.And pretty yellow spots in the centre on the oral disk, as well as along the short arms.

These soft shores remind us very much of Changi. As in Changi, there were also some peacock anemones with attendant black phoronid worms, several small and large carpet anemones some with tiny shrimps in them. The sea pens are not abundant here, I saw only one stick-like Virgularia sp. Also missing were brittlestars, biscuit sea stars, thorny sea cucumbers and mantis shrimps that we regularly see on Changi. Although there were lots of sand collars, I didn't manage to find any living moon snails.

There were not many moon crabs (Family Matutidae) at Pasir Ris. I saw this rather 'weedy' moon crab. It was still alive, although it wasn't very lively.Its body was not only overgrown with seaweeds, but also had other little animals living on it. I'm not sure what's happening. Is the poor crab sick? Paratised by some nasty parasitic barnacle? On Changi, we usually see this situation more on the swimming crabs and not the moon crabs.

There were several Sentinel crabs (Macrophthalmus sp.) on the shores.In the same larger group as fiddler crabs, these crabs also have eyes on long stalks. But their pincers are equal sized.

Further up on the higher shore, there was this other crab in a burrow, also with long eyestalks.Is it also a Sentinel crab or some other crab? I have no idea.

And what a lovely surprise to come across a seahorse (Hippocampus kuda)!A very pregnant papa seahorse he was!

Chay Hoon found SIX of these little black yellow-spotted Gymnodoris nudibranchs!
These little nudibranchs require a keen eye to spot as they are tiny and well camouflaged.

She also found several of these odd looking flatworms.There were lots of them out and about this morning. Even blind me saw some of them. The odd thing about them is the pair of 'tentacles' sticking out of the body. I have no idea what kind of flatworm this is.

We had a pair of these flatworms in the box to take closer photos of them ...Suddenly the little one attached itself to the big one and a tangle of twisting ensued. Oops. Possibly there is something going on to do with baby flatworms?

Flatworms are hermaphrodites. Each flatworm has both male and female reproductive organs. So when two flatworms meet they can exchange sperm. Shortly after twisting about for a while, the two flatworms calmly separated and moved off in separate directions.

Wow, what a fantastic morning out on the shore. More questions than answers, but that goes to show how much more there is to learn and discover about our shores!

As we were exploring, a friendly passerby with a plastic bag approached us. We showed him some of the fascinating marine life there. We asked about the contents of his bag and he showed us a dead fish, several hermit crabs and sea stars. He intended to try to use them as bait, 'for fun' in his fishing later on at high tide. We persuaded him to return all the other marine life and just use the dead fish. He was very friendly and agreed to do so.

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