08 December 2010

Pulau Ubin's other special shores

Aside from Chek Jawa, there's amazing marine life on other parts of Pulau Ubin too!
Yesterday, a small team head out to check it out. It's been a year since Kok Sheng arranged for us to visit this shore. Is it still alright?

Pulau Ubin has beautiful rock formations including amazing 'fluted' rocks. You can read more about these unique and fascinating rock formations on November's Ubin Stories blog and Joseph Lai's eart-h.com.
Along these elegant fluted rock edges, all kinds of colourful marine life have settled down.
Mostly sponges, but also many ascidians and some hydroids.
There is a lot of orange-striped white Thumbs up sea squirts (Polycarpa sp.). Although the rocks are well coated with living animals, I couldn't find any nudibranchs or flatworms. Perhaps it was the rain. But later on, Kok Sheng found a pair of Chromodoris lineolata, nudibranchs that we more commonly see on our Southern shores!
Hmm, this is odd. A large pink ascidian with legs?
No, it's a rather feisty Sponge crab (Family Dromiidae) that is using the ascidian as a camouflaging cap. The crab has bright pink pincer tips! See how the crab has two pairs of little legs bent over its back, which it uses to cling onto its living camouflage!
The usual sea cucumbers are also seen: a few Thorny sea cucumbers (Colochirus quadrangularis) and one orange sea cucumber.
I saw one large Haddon's carpet anemones (Stichodactyla haddoni), and on the rocks, something that might be the ball-tip sea anemone. Kok Sheng later found a large cluster of blue Ball-tip sea anemones.
Kok Sheng had a look under the stones and they are very much alive. Here, he has found a tiny Rock star (Asterina coronata), a Little African sea cucumber (Afrocucumis africana) and patches of many different animals that encrust the stone. After looking at the underside, we always remember to gently put it back the way we found it.
There are also patches of seagrasses on the shore. Here, Geraldine found a Biscuit sea star (Goniodiscaster scaber) and an tiny orange Cake sea star (Anthenea aspera)!
I also came across this huge jellyfish washed ashore. It was about 30cm in diameter.
Some parts of the shore is littered with lots and lots of pieces of branching coral. There must have been a reef here in the past!
There are even some large chunks of dead coral. I wonder when and why the reef here died.
Alas, the weather soon turned for the worst, but we continued onward as there was no lightning.
I found out that we can see different animals and behaviour when it rains! Lots and lots and LOTS of tiny crabs started moving about on the sand. They were hardly bigger than the sand grains. Can you see them?
A closer look at the very tiny crabs. I have no idea what they are.
Usually, during low tide, the tiny periwinkles (Family Littorinidae) are immobile. But with the rain, many were quite actively moving about on the rocks. Wow, they sure have relatively large 'heads' with thick tentacles!
It's amazing what you can find if you look closely at the rocks. The clusters of tiny flasks are the egg capsules of Drill snails (Family Muricidae). The yellow ones have not yet hatched, while the purple ones are about to hatch or have already hatched. While the little blobs with colourful stripes are Lined bead anemones (Diadumene lineata).
There were many clusters of small and clean Drills. These snails are predators and can literally 'drill' holes into the shells of other animals living on the rocks.
There were also zones with tiny clams that resemble Nest mussels (Musculista senhousia) both in shape and the way they form a nest with their byssus threads. Kok Sheng, however, points out that the usual Nest mussels have a pale, patterned shell. While those we saw were all black.
And the Drills seemed to be busy feeding on the tiny mussels!
These twisty tubes are made by snails and not worms! The Worm snails (Family Vermetidae), like other snails have tentacles and a 'door' or operculum to seal their shell opening.
I also saw a nice Spiral melongena snail (Pugilina cochlidium) which clearly shows the 'hairs' (called the periostracum) arranged in spirals on the outer surface of the shell. Usually, the hairs are so clogged up with silt that I can't see the individual hairs.
There was a long low rock formation on the shore, with a hole so that the entire thing looks like some kind of animal. We couldn't quite agree what animal it might be. I think it looks like a monitor lizard!Alas, some people had a picnic at this secluded spot, and left a big pile of rubbish behind.
A very long line of fishing nets have been strung out on some parts of the shore. I looked and didn't find any trapped animals on it.
As the tide turned, the sun set and the rain died down. And it was time to leave Pulau Ubin.
We were wet and soggy, but glad to have had a chance to look at this shore again.

Later this evening, I'll be going to check on the other part of Tanah Merah that was affected by the oil spill. Let's hope we have better weather!

Others who posted about this trip:

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