31 July 2012

Living shores of Pasir Ris!

Pasir Ris has a lovely intertidal shore that is full of surprises. Today, the shore was carpeted in a lush thick layer of fresh green Sea lettuce (Ulva sp.).
Lots of little critters hide among the Sea lettuce including this pretty Cerberilla nudibranch (Cerberilla sp.). I also found a new sea anemone and other curious creatures.


My sea anemone surprise was this tiny little sea anemone. In the past, I usually dismiss it as a young Peachia anemone (Peachia sp.). Today I took a closer look, I realised it had a 'hard' body column encrusted with sand, somewhat like the Wiggly star anemone. Another Edwardsid?
I came across the Seagrass sea anemone again. I last saw these at Cyrene Reef.
Lots of blobs seen on the shore can be confusing. The blob on the left is an 'uprooted' Ball sea cucumber (Phyllophorus sp.). The smooth one on the right is a sea anemone!
It's actually the sea anemone that Dr Daphne is interested in having a closer look at. I'm not only lucky to find it, but super lucky that the anemone is also already 'uprooted'. It is usually very deeply embedded in the ground.
I didn't realise this bumpy blob was an octopus, until I got much closer. These seagrass octopuses look quite different from the kind we usually seen on our reefs.
Here's another confusing blob. It's a sea cucumber. At first I thought it was a young Ball sea cucumber (Phyllophorus sp.), but after taking a closer look, I'm not too sure.
I did the intertidal survey at Pasir Ris. This is good to do, not only because it generates data, but also because it forces me to take a really close look at what is out there! Besides the Sea lettuce bloom, there was also still lots of lush Spoon seagrass (Halophila ovalis) on the shore. Here's a slide show of the transects I did today.
For the survey, I took a closer look under the Sea lettuce and found all kinds of animals. This transect had lots of Spiral melongena snails (Pugilina cochlidium) and many hermit crabs as well as other tiny crabs and critters.
In some transects, the Sea lettuce was very firmly attached to a carpet of Nest mussels (Musculista senhousia)!
The most abundant large animals on the shore today were Ball sea cucumbers (Phyllophorus sp.) and Black sea urchins.
Aside from the Ball sea cucumber, I only saw one Orange sea cucumber and one Purple sea cucumber.
There were many Plain sand stars (Astropecten sp.), but I only saw one tiny Biscuit sea star (Goniodiscaster scaber).
I came across several of these lively brittle stars with arms that look like bottlebrushes.
The Sea lettuce is also a great place for tiny fishes. There were several Seagrass pipefishes (the one in the photo seems to have a fish leech on its head, eeks). Also a tiny green filefish (Family Monacanthidae) and lots of little gobies (Family Gobiidae).
I saw the noodly tentacles of a Spaghetti worm which disappeared completely into the silt when I looked under the Sea lettuce.
There are all kinds of crusties in the Sea lettuce. Many snapping shrimps (Family Alpheidae) of all kinds, tiny and not so tiny shrimps and porcelain crabs too.
I saw two small carpet anemone (Stichodactyla haddoni). Also some cerianthids (Order Ceriantharia), which are sometimes called Peacock anemones although they are not true sea anemones.
Among the special snails I saw today was a Calf moon snail (Natica vitellus), a Tiger moon snail (Natica tigrina) and also good to see many large Olive whelks (Nassarius olivaceus). The one in the photo had a barnacle growing on its shell. Half buried in the mud were also many Gong-gong snails (Strombus turturella).
In the shallow pools, there were lots of little crabs, gobies (Family Gobiidae) and snapping shrimps (Family Alpheidae).
How nice to see a Spearer mantis shrimp (Harpiosquilla sp.)! I haven't seen one for a long while. It wriggled away rapidly into the Sea lettuce.
There were also lots of Stone crabs (Myomenippe hardwicki) especially near the scattered rocks on the shore, which were encrusted here and there with Rainbow sponge (Suberites sp.) and dotted with small colonies of Zebra coral (Oulastrea crispata).
This beautiful shore is afflicted with one of the worst littering situation on our shores, and earlier in the year incidents of mass fish deaths. I wish I could check up on this shore more often. My last visit to the Pasir Ris intertidal was nearly a year ago! There are just not enough low tides to do all our shores as often as I would like to.

The last series of super low morning tides for the year kicks off this week. Last chance to see our favourite shores at their best.

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