22 September 2009

Clamless on Kusu

We're back near sunset for another low tide trip at Kusu Island. Hoping to find Giant Clams for Mei Lin's project.
My plan was to check out the sliver of reefs on the outside of the sea walls. This is what this narrow strip of reef looked like when I last visited about 5 years ago.

Kusu Island's reefs are just opposite Singapore's main business district!
Living reefs of Kusu Island, Singapore
But the tide didn't seem to go down. After waiting for a while, the team gave up and went back to the main lagoon. The tidal predictions tend to be a little off during the period when the spring tides switch from morning to evening and visa versa. On the way back, I had a quick look at the shore. It seems to be still there. We shall return at a much lower tide, because Mei Lin is sure there is at least one Giant Clam on Kusu!
Wow, the weather was seriously building up over the city! Fortunately, we were spared and only got a sprinkling now and then.
Though we were Clamless, I did see one enormous mollusc on this trip. It is the Giant top shell snail (Trochus niloticus) with a base bigger than the palm of my hand! This humungous snail is listed as Vulnerable in our Red List of threatened animals of Singapore.
Patiently waiting, I finally managed to get a look at the magnificent animal. It has a white body and speckled foot. As well as short tentacles. The upper side of the shell is usually well camouflaged with encrustations that match the surrounding rocks where it lives.
The water in Kusu's lagoons are usually murky, even at low tide. But this doesn't mean there's no life here. There are lots of hard corals as well as other marine life. Particularly abundant are boulder shaped corals, and patches of branching corals as well as lots of Blue corals (Heliopora coerulea). Wedged among them are Frilly anemones (Phymanthus sp.) of various colours and patterns.
Living corals keep themselves clean in murky waters by producing mucus. This traps the sediments and sloughs off, keeping the animals clear. Doing this, however, takes up energy and resources. So too much sediment can be stressful for corals. There has been massive dredging going on near Kusu Island almost the whole of this year.
Besides hard corals, Kusu is also a great place to have a look at the well named Magnificent anemones (Heteractis magnifica). There are several on this reef. At low tide, they tuck their tentacles and oral disk into the body column and often look like giant purple balls.
Also common on the shore were Giant carpet anemones (Stichodactyla gigantea). Some had tiny anemoneshrimps (Periclimenes brevicarpalis) living in them. Sadly, none of us could find any anemonefishes in either the Magnificent or Giant anemones.
To us, it seemed there has been an increase in the number of Haddon's carpet anemones (Stichodactyla haddoni) in both lagoons. I also saw this little anemone, which might be Stichodactyla tapetum. These are not very commonly seen on our southern shores.
As the sun sets, more animals become active and we keep on exploring the shores.
It seemed to be my day for flatworms. Near the reefs, there was this pretty black flatworm with orange and white trim (Pseudobiceros uniarborensis).
And on the patches of very tiny Spoon seagrasses (Halophila ovalis), I saw this olive flatworm that we have been seeing at Tanah Merah in numbers. I still don't know what it is exactly, but it sure is pretty.
Most surprising was the large number of black speckled flatworms (Pseudobiceros stellae) in the seagrass area. I saw ten of them in a small area. They were spaced well apart, but perhaps they were getting ready to meet up and mate? There's so much more to learn about our shores.They came in various shades of dark and various degrees of speckledness.
There were also scattered groups of little Orange fiddler crabs (Uca vocans) on the seagrass area.
And even the Common sea stars (Archaster typicus) wandered among the seagrasses. These were more plentiful in the sandy areas, where large white Oval moon snails (Polinices mammatus) ploughed the wet sand.
Much earlier on, we checked out the pool at the temple on the island. And I couldn't believe my eyes when I saw several baby sea turtles on the water surface.
They are really cute. To swim, the front flippers are held against the body while they paddle with their hind flippers.
Chay Hoon noticed that they would stop moving when the schools of mullets swam near them. We also wondered whether they would be vulnerable to birds of prey. Indeed, they seem to prefer to hang motionless around the leaves and debris floating in the water, where they are quite hard to spot.
We waited a while and were rewarded with a glimpse of the big sea turtle swimming briefly out of the murky depths into shallower water.

Kusu Island is a full of history too. More about Kusu Island on the wildsingapore website.

To see the marine life of Kusu Island for yourself, join the public walk conducted by volunteer guides from the Blue Water Volunteers.

More blog posts about this trip


  1. I didn't know there were sea turtles in that lagoon! I was looking inside the last time we were there (in July), but saw only halfbeaks.

    Oh dear, looks like those hatchlings really ought to be living in much better conditions.

    By the way, are they really green turtles and not hawksbills? It would be very interesting to find out where they came from, especially if these were obtained from local waters.

  2. They were all caught and released to the open sea due to the publicity of some pictures of these baby turtle last Wednesday... Underwater said they are hand tight, Zoo refused to comment... Sentosa Developement corp, who oversees southern islands said they caught all of them, and released them to the open sea... &%#$...

  3. i thought they were green turtles but ACRES confirmed they were hawksbill turtles.



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