Thursday, May 14, 2009

Pasir Ris after the rain

The clouds looked really bad this morning when we were setting off to Pasir Ris. Usually, bad weather doesn't deter us from cancelling a trip because who knows, the weather might clear up?

Indeed, it was raining for a while when the tide already went low, exposing the sand bar in the intertidal area.

There was no thunder or lightning at first and so we went ahead, in a die-hard manner, to explore the shore after we got equipped with our poncho and umbrella. Here we have James and Mei Lin.

BUT, soon the lightnings drew near and we waited at the park shelter for about 15 minutes before we decided to hit back to the shores.

Despite the earlier downpour, we could still spot quite a good variety of animals after the rain.

One of the first few animals spotted will be this Moon crab (Family Matutidae). It has nice pinkish spots on its carapace. This crab is a good burrower!

There were also several Tiny swimming crab (Portunus pelacigus) scurrying around the shore when the rain drizzled. It could probably be just trying to avoid the rain.

Unfortunately, I found this dead Sponge crab (Family Dromiidae) tied together with several fishing lines. How sad that these marine thrash left behind by irresponsible fishermen eventually will kill the marine organisms living in the sea. And to think that this sponge crab was the biggest I've ever seen. It was almost as big as a Thunder crab (Myomenippe hardwickii) which I also spotted today underneath rocks.

At Pasir Ris, it is not difficult to find the numerous Hermit crabs (Infraorder Anomura) in different types of shells and different species.

It was quite a pleasant find to spot this Striped hermit crab (Clibanarius sp.) on a Baler volute shell (Melo melo). Which means there are Baler snails at Pasir Ris! It is good because the Baler volute is listed as 'Endangered' in the Red List of threatened animals of Singapore due to habitat loss.

This hermit crab (living within the snail shell) is definitely a Singaporean because it is so kiasu with a huge anemone attached onto the shell, which helps to fend off predators.

At a particular part of the high shores with lots of washed up Sea lettuce seaweed (Ulva sp.), there are many of these Black sea urchin (Temnopleurus toreumaticus). Some are dead with these test.

Left: upperside, Right: underside of the sea urchin.

And you will be amazed to know that there's more to the mouth of the sea urchin at the centre of its underside.

Most of the urchins have a large fat banded worm-like animal is seen curled around the mouth of the sea urchin. I wonder what the worm does to the sea urchin. What is their relationship... hmm.

Ria later found a dead test of the heart urchin (Order Spatangoida)! So there's really heart urchin at Pasir Ris. Henrietta saw a heart-urchin looking urchin earlier this year at Pasir Ris as well.

More about the black sea urchin and the heart urchin in Ria's post of today's trip at her Wildshores of Singapore blog.

Mei Lin and James pointed out to me several of these weird looking blobs on the sand.

They are mostly about 1cm-2cm wide but their sizes do vary. And on their upper surfaces there are fine intricate flower-like patterns. On their underside, there was a depression on this particular blob with shells stuck within them. Are these blobby creatures ascidians?

Surprisingly, today there were quite a few finds of this conch (Family Strombidae) that we have sighted before at Changi and Tanah Merah as well. We suspect it might be Strombus succinctus.

Then we found more conches, this one is apparently a small one. It has a thin shell. We are unsure what it is, but it can possibly be a young Gong-gong or Pearl conch (Strombus canarium).

To add on to the confusion, there was this adult-sized conch that still has thin shell at the opening. It is thought that the adults of the Gong Gong have a thick shell and large flared lip. Is this still Strombus canarium?

Well, I'm just too lazy to check out the monographs now to solve all the strombid conches confusion. But it certainty increases my respect to taxonomists out there!

Seeing many sand collars of moon snails around and wondering whom these collars belong to, the mystery was solved when James found several Tiger moon snails (Natica tigrina).

Sea cucumbers spotted today will be the Ball sea cucumber (Phyllophorus sp.) on the left and the Purple under-a-stone sea cucumber. Indeed, this cucumber was under a stone, and also within the stone! Haha.

For some reason, we did not spot one, but at least three of these Peanut worms (Phylum Sipuncula). Peanut worms were once so plentiful in Singapore that they were collected and fed to ducks. But now, they are only sometimes encountered in mangroves and on soft ground (silty or muddy).

Another worm found will be this Red ribbon worm (Phylum Nemertea). Most ribbon worms are voracious predators, often specialising in a particular prey although some will eat a wide variety of prey including other worms, crustaceans and molluscs.

I found this uprooted Common sea pen (Pteroides sp.) where its orange foot usually should be buried in the ground. But there wasn't any resident Painted porcelain crab within this sea pen.

Ze Lin was quite apt at spotting tiny yet exciting marine animals like this real tiny Spearer mantis shrimp (Harpiosquilla sp.).

Henrietta and Ze Lin later found this cute octopus (Family Octopodidae). This octopus is frequently seen at our northern shores.

And for the TOP find of the day....

The best find must be this Tripodfish (Family Triacanthidae) found by Mei Lin and James. It's yet another first time for me! This tripodfish is really small, about 2cm across. Though it was difficult to photograph this small and active fish swimming around, all the back breaking moments and "sour" squattings were worth it.

The tripodfish does indeed have a tripod made out of a pair of long, rigid pelvic fins and the tail fin. They hunt for small fish and bottom-dwelling animals, sucking these up with their pointed mouths. Pointed mouths just remind me of the special Longhorn cowfish find at Tanah Merah two days ago.

Well, it's a good trip nevertheless of the rain. This marks the end of the six-day consecutive field trip low tide series. One week to rest and off we go for more low tide adventures. The next series will be the first super duper lows of the year!

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