Tuesday, July 03, 2012

Soft and silty Changi Beach

Despite today being a school day, I still signed up for a field trip session.
Three ladies went to a rocky part of Changi Beach to explore.
This shore we visited used to be very rocky, but it is now rather silty and the substrate can be quite soft.

The shore is covered with shells of bivalves. They are dead bivalves though.
Even though there are many dead bivalves on the shore, I did see some live ones.
Some type of cockle. Notice how the shell tails off on one side.
Cockle - a small and a medium size.
Pretty Bean-shaped venus clam.

There were a number of this fellow buried in the silty ground with the shells opened. It looks like a fan clam but I have never seen the clams in such manner. It looked like there is a inner chamber inside this animal.
Fan clam?
A huge "sea-harm" (Anadara sp.) opens its shell to show me its muscles. It is alive.
I tried to shift it and it closed its shell a bit and reopens them again. So I thought the original position is good enough for me.
The more I look at the above two images, it looks more like the cockle is singing.
Another interesting bivalve I saw was this. It has pretty ridges on the shell surface.
Unknown bivalve
Other than bivalves, another kind of animals with shells I saw were the moon snails. I only managed to see two moon snails today - the Pink moon snail (Natica zonalis) and Tiger moon snail (Natica tigrina).
Pink moon snail
Tiger moon snail

The largest shell animal I saw on this shore would be the Noble volute (Cymbiola nobilis).
Noble volute (underside)
The sea cucumber were abundant on the shore too. Many were out on the surface and there are also others buried. There were Pink warty sea cucumber (Cerodemas anceps), Thorny sea cucumber (Colochirus quandrangularis) and perhaps an Orange sea cucumber.
Pink warty sea cucumber
Above: Thorny sea cucumber
Middle: Orange sea cucumber?
Feathery feeding tentacles of Thorny sea cucumber
Further in the echinoderm phylum are the sea stars.
I have come to realise that once I see my first sea star, the rest of the sea stars will slowly appear. (Brittle stars not counted though as they are plenty on our shores).
There were the plain sand star (Astropecten sp.), Biscuit sea star (Goniodiscaster scaber) and many brittle stars.
Plain sand star (top view)
Plain sand star (underside)
Biscuit sea star (top)
Biscuit sea star (underside)
Upside down brittle star (Ophiothrix sp.)
Blue-lined brittle star (Ophiothrix lineocaerulea)
This disk diameter is around 2 cm long., comparing its size to the seaweed.
How could I have miss the sea urchins when they are everywhere???
Black sea urchin (Temnopleuris sp.)
White sea urchin (Salmacis sp.)
In a shallow pool, a Three-spined toadfish (Batrachomoeus trispinosus) was swimming around and I had a hard time capturing an image of it. I could only capture this.
As I was flipping one of the many Window-pane clams, I found two porcelain crabs. This species of porcelain crab is commonly found under stones.
Porcelain crab
There were many anemones of various sizes.
Common cerianthid
Unknown anemone
Haddon's carpet anemone (Stichodactyla haddoni)
Swimming anemone (Boloceroides mcmurrichi)
Banded cerianthid
Tiger anemone
Tiger anemone with visible body column
I only saw one Spiky sea pen (Scytalium sp.). It is only when I processed the images that I noticed a porcelain crab on one of its 'leaves'. I was searching for commensals on this sea pen but couldn't find any on location.
Spiky sea pen
There were quite a number of sea pencils and slender sea pens (Virgularia sp.) on the shore too.
Slender sea pen
Sea pencil
The rice dumpling festival was over for two weeks and we found recently "littered" rice dumplings on the shore. They were scattered along the shoreline.
I think that whoever did this was trying to commemorate the rice dumpling festival, following the story of how the villagers threw rice dumplings into the waters in hoping that the fish will not consume the heroic figure (Qu Yuan). However the folklore mentions that the man jumped into a rive, not the sea. Oh well... This dumpling was later picked up by a stray dog, but I don't think he enjoys the super salty dumpling.

Soon the tides came in, which signals the time for me to head back to school to teach.
Yawn, I'm going to be zonked out (and I felt like a half zombie in school).

Read about Ria's wonderful findings on this trip here.

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