10 October 2009

Another feeding frenzy at Tanah Merah

A shore can be a violent place for small creatures!
Yesterday, I came across this sinister looking Haekel's anemone (Actinostephanus haekeli) with tentacles full of little fishes.

Here's a closer look at one of the little fishes that it had caught. The fishes seem to be Glass perchlets (Family Chandidae), which are abundant on this shore.
When I first chanced upon the anemone, it was a ball with all its tentacles tucked into its body. Once the fishes stopped struggling, the anemone relaxed its tentacles. Perhaps getting ready to pop them one by one into its central mouth? It was really slow about deciding what to do, so I didn't stay to watch the conclusion of this gruesome carnage.

We went to another part of Tanah Merah today. And this time kept to the high shore as the water was a bit too high to get to where the rocks were. So I got to see some other kinds of animals. Like this pretty peacock anemone with banded tentacles. It's much larger and more colourful than similar ones I've seen elsewhere.
Another elegant peacock anemone is this small one with and inner ring of very short tentacles around the mouth.
I also saw one anemone on a living snail. I don't know why, but these are not as common on Tanah Merah as they are on other shores in the North.
Another special find was this strange fan worm that I rarely see. These seem to be found on the higher shore in silty-sandy areas.
It was really nice to come across a very large Painted sand star (Astropecten sp.). My first for Tanah Merah. These sea stars are commonly encountered on our Northern shores. Chay Hoon also found another tiny star that might be a juvenile Cake sea star (Anthenea aspera) or Spiny sea star (Gymnanthenea laevis).
The Common sea stars (Archaster typicus) were just as abundant here as they were on the other part of Tanah Merah we visited yesterday. That's great as these sea stars are no longer seen on our Northern mainland shores.
Today, for the first time, I saw a two-armed Common sea star! It was probably originally a normal five-armed sea star. That some how lost most of it arms. Sea stars can 'drop' off an arm if they are alarmed. Which is why we should not handle sea stars and especially NOT pick them up by their arms.
While the arms can regenerate, this takes time. Meanwhile the sea star is disadvantaged. We can see two tiny arms growing from the stumps of the old one (left photo). The white spot is the madreporite, a plate through which the sea star sucks in seawater to pump its body parts. This sea star also seems to have some external parasites on it (right photo). A white round thing, and a small parasitic snail with a long conical shell.
Later on, we saw a three-armed sea star! There were also four-armed and six-armed sea stars.
One area also had lots of large Cake sand dollars (Arachnoides placenta). But I didn't come across any sea urchins. Also no luck (yet) with the special snails that eat these echinoderms. Other echinoderms seen include some Synaptid sea cucumbers (Family Synaptidae).
The water on the sandy upper shore was full of blue-tailed shrimps (Family Penaeidae)! Including this one with red markings. There were also Flower crabs (Portunus pelagicus) some that looked like they had just moulted, Moon crabs (Ashtoret lunaris), little Sentinel crabs (Macrophthalmus sp.) and Elbow crabs (Family Parthenopidae).
I saw few of these intriguing snails that I've never seen before. I have no idea what they are.
Alas, I didn't see any slugs. But I did come across this little cuttlefish (Family Sepiidae)! It looked just like brown seaweed.
Even on the high shore, we could see special fishes. This Brown sweetlips (Plectorhinchus gibbosus) looked just like a leaf drifting in the ripply waters.
A Variable blenny (Petroscirtes variabilis) also drifted about in the gentle waves, with its body curled into an unfish-like shape.
While this colourful Diamond wrasse (Halichoeres dussumieri) was just lying on its side on the sand. I'm not sure if it's dead. I never touch this fish because it can give a nasty bite that draws blood!
We eventually met up with Chay Hoon who had spotted a Hollow-cheeked stonefish (Synanceia horrida)! As well as one of the Estuarine seahorses (Hippocampus kuda) that Collin tagged on our earlier trip there. Alas, we didn't see any other seahorses, tagged or otherwise. Although I did search hard for them.

Sadly, in the deeper pools, there were several people laying several drifnets. Even before the tide turned, the net had already trapped many fishes.
On the high shore, there is a great deal of litter. This shore never gets cleaned so debris just builds up over time as they drift in with each tide.
On one end of the shore, there is some kind of construction going on with excavators and barges, which continued even after sunset.
We had a gentle sunset today, over an amazing 'reclaimed' shore that is actually being reclaimed by marinelife.
Before we started the trip, while Stephen and I waited for Eddie to show up, we amused ourselves by looking for and finding spiders on the trees in the carpark. There were two Two-tailed spiders (Hersilia sp.) that were perfectly camouflaged on the bark. On one tree was a male with a pair of huge palps in front of him (left photo). On another was a fat female (right photo). According to Joseph Koh, they immobilise their prey by spreading silk while jumping over and running around it.
It was a great trip to Tanah Merah! And we tried a route which allowed us to park without risking a traffic ticket but involved a long long LONG walk on a road full of speeding vehicles. Perhaps the traffic ticket is a better risk.

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