Sunday, June 7, 2009

More Tanah Merah surprises


Update: Check out posts by the others on today's trip: Return to Tanah Merah by Ria, All crabbed out at Tanah Merah by Liana, Tanah Merah by James, Tanah Merah 3.30-6am by Janette, and Red carpet and Eye can see you by Marcus.

Just a day after my first visit to this part of Tanah Merah, I'm back once again to explore another stretch of coast.

This area is separated from the shore I visited yesterday by a canal, and also features a huge area of sandy shore behind a seawall. At first, one should expect to see the exact same fauna I encountered yesterday, and in a way, I did; the pools were full of gobies and little shrimps and prawns, and there were quite a number of swimming crabs (F. Portunidae).

Strangely enough though, the swarms of zoned horn snails (Batillaria zonalis) that carpeted the shore on the other side were completely absent, as were the shoals of bigfin reef squid (Sepioteuthis lessoniana) that were following Ria.

I found a couple of very shy land hermit crabs (Coenobita sp.) up on the high shore, amongst the rubbish. I need to learn how to identify the different land hermit crab species; there are several species found in the region, and I'm keen to find out just which species can be found in Singapore. There are several online guides that cater to those who keep land hermit crabs as pets, such as this very comprehensive guide to several species of land hermit crabs more commonly found in captivity.

The rocks are covered with dense numbers of chameleon nerites (Nerita chameleon).

There is an amazing variety of shell colours and patterns within this single species.

Some of the nerites appear to be busy making more nerites.

And this is the result.

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I managed to find a couple of scaled nerites (Nerita histrio).

I found this sea anemone (O. Actinaria) on the damp sand, looking very miserable and waiting for the tide to return. I'm not sure what sort of anemone it is.

I didn't check if this horn-eyed ghost crab (Ocypode ceratophthalmus) was dead, or whether it was just an empty moult.

There were plenty of snapping shrimps (F. Alpheidae) in the pools.

Here's a weird-looking shrimp I've never seen before.

I found this blue swimming crab (Thalamita danae) snacking on what appears to be a spotted moon crab (Ashtoret lunaris).

This newly-moulted flower crab (Portunus pelagicus) was missing both its pincers. I wonder how it's going to grab its food or defend itself.

This is the front end of some sort of polychaete worm (C. Polychaeta). The appendages around what passes for a face in this worm make me wonder if it might be a miniature relative of the giant reef worm (Eunice aphroditois).

I found a couple of very interesting shells.

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This appears to be some sort of helmet shell (F. Cassidae).

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While this one is a fig snail (Ficus sp.). Finding the empty shell of a fig snail here on Tanah Merah is very interesting, as live fig snails have been encountered only on another stretch of shore, much further down the coast.

Here's one of the live fig snails that Ria found on that trip last December.

By the way, if you didn't already notice, this snail has the same genus name as the plants known as figs. While it can lead to plenty of confusion, it is allowed according to the rules of biological nomenclature.

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There were quite a few pearl conch (Laevistrombus canarium) in the soft sediment.

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Like yesterday, I noticed this firebrand murex (Chicoreus torrefactus) only when it moved.

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This strange-looking snail had such a dirty shell that it was hard to make out its shape and any distinguishing features. I now regret not trying to wash off all the muck before taking a photograph. Based on the photographs in A Guide to Common Seashells of Singapore, I think it might be a dolphin shell (Angaria delphinus), which others have found on this shore before.

Many of the rocks and seaweeds are covered in green gum drop ascidians (C. Ascidiacea).

Everybody was thrilled when I found this large Persian carpet flatworm (Pseudobiceros bedfordi).

There were quite a few interesting fishy finds.

More Bengal sergeants (Abudefduf bengalensis) were spotted today, including some very tiny ones.

There was also a very cute little copperband butterflyfish (Chelmon rostratus).

Later on, when most of the others had started to head back, I came upon this large school of striped eeltail catfish (Plotosus lineatus).

The most exciting finds however were those that I didn't manage to photograph at all. On a couple of occasions, I caught glimpses of the squirrelfish (Sargocentron sp.) that Ria had spotted yesterday.

In fact, I was trying to photograph a squirrelfish when I saw a long, thin eel-shaped creature, about 15 centimetres in length and dark brown, slithering in the water amongst the rocks. I wasn't sure if it was a snake eel (F. Ophichthidae) or moray eel (F. Muraenidae). The eel vanished beneath a rock, and then poked its head out again. A quick look at the head allowed me to conclude that it was a small moray eel, and based on the coloration, it was most likely an estuarine moray (Gymnothorax tile). There was a flash of silver, and I saw that it had seized a small fish in its jaws. Then it disappeared once again.

I was keeping as still as I could, waiting for the eel to make an appearance again, when I saw something moving in a crevice right beneath me. I took a quick look, and was surprised to see that it was a second, much larger estuarine moray! I never got to see the entire body of the eel, but my guess is that it was about 30 centimetres in length. I got a good long look at its head, but it disappeared just as I was bringing my camera into position.

However, I did manage to snap a photo of a section of its body. Apologies for the horrible quality of the shot.

I would have wanted to stay and wait for the moray eels to emerge, but I had to grudgingly head back and join the others. Oh well. I'll be back sometime soon I hope.