12 August 2011

Pasir Ris is still alive!

How nice to see this weird slug on Pasir Ris! Thanks to Chay Hoon who taught me how to find this Volvatella slug (Volvatella vigourouxi) among the seaweeds that it feeds on.
It's been nearly a year since I last visited this shore in Sep 2010. Last year, there was massive construction to rebuild the seawalls. How did the marine life cope?

There are still lush seagrass meadows of Spoon seagrass (Halophila ovalis) with lots of large green leaf blades.
Here and there, the seagrass meadows were dotted with small colonies of Zebra coral (Oulastrea crispata), banded ceriathids (Order Ceriantharia), swimming anemones (Boloceroides mcmurrichi) and one small carpet anemone (Stichodactyla haddoni).
It was nice to come across this lovely Glass anemone (Dofleinia sp.).
There were also many small fishes lurking among the seagrass blades including several Common mojara (Gerres oyena), tiny Longspined scorpionfish (Paracentropogon longispinis), Black eeltail catfish (Plotosus canius), many Whitings (Sillago sp.). I also saw one tiny flatfish, and of course, many tiny gobies (Family Gobiidae).
Today, I noticed many snapping shrimps (Family Alpheidae) in the soft silty sand among the seagrasses. Some of them seemed to be in a relationship with a goby. The shrimp would always have one of its antennae touching the goby, and both the shrimp and the goby would disappear into the same burrow.
These two animals zipped back into the shrimp burrow after I took this shot.
I was focusing on the goby and only realised at home, the snapping shrimp behind it with its antennae on the fish.
In pools, there were lots of these glass shrimps (Palaemon sp.). I also saw several Stone crabs (Myomenippe hardwicki).
In shallow pools, there were lots of hermit crabs of all sizes and various kinds.
There were still plenty of Ball sea cucumbers (Phyllophorus sp.) everywhere.
Also still abundant were Plain sand stars (Astropecten sp.). But I didn't see any other kinds of sea stars or sand dollars or sea urchins or brittle stars.
Many of the sea stars, however, were badly infested by parasitic snails (see the tiny white conical shells?). Near the snails were white spheres: their eggs? Some of the stars had big 'holes' in their bodies. Eaten by the snails? Ouch.
One again, I saw the Calf moon snail (Natica vitellus), that first mystified me on this shore.
How interesting to come across this tube worm out of its tube. I'm not sure how it came to be outside its tube.
It's hard to get a good photo of these black phoronid worms (Phoronis australis) that live with a cerianthid. I've long tried to get a photo with the cerianthid somewhat extended and the worms extended too. Today, I think I've finally got it! I've also been trying to get a photo of phoronids with cerianthids of other colours. But so far, I've only seen them with white ones. Hmmm...something to learn more about!
As usual, I notice white spheres held in the spiral fan of the phoronid worms. In addition, I also notice a kind net of scum around the worm. Do they also produce scum to gather food? Hmmm...
I only came across one purple branching sponge (Callyspongia sp.), but it was a large one. The stones on the shore seem rather bare of encrusting marine life.
Besides seagrasses, I also saw large clumps of seaweeds such as Caulerpa sertularioides, Gracilaria sp. and Ulva sp. The shore on most parts remained soft and silty at the low water mark, and were well covered by seagrasses. I noticed some new hard sand bars at the low water mark on some parts of the shore. Perhaps these sand bars are due to the recent work done on the beach? I should try to revisit soon to keep tabs on how this shore is doing.

2 comments:

  1. Hi Ria,

    The parasite snails you've found belonged to the family Eulimidae.

    The Eulimids are specialised snails that parasitise on echinoderms. They are frequently found near the anal region of sea cucumbers, sea stars, sea urchins, feather stars etc. There are even some of which have colonised the guts of sea cucumbers!

    Best,
    JK

    ReplyDelete
  2. That's gruesome JK! Thanks for the information!

    ReplyDelete

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