Wednesday, June 11, 2008

Intertidal Life of Raffles Lighthouse

It's been almost a year since I last went to Raffles Lighthouse, and thus I was really excited to visit it again this time round two days in a row :)

Raffles Lighthouse is located on Pulau Satumu, the southern most island that belongs to Singapore. Since it's quite a distance away from the main shipping activities and reclamation work nearer to mainland Singapore, the water surrounding the island has less sediments, and the area was densely covered with corals which require clearer water to thrive.

As such, one of the major highlights of visiting Raffles Lighthouse is looking at the pretty corals exposed during super low tides!

There are corals everywhere, and we had to walk on the edge of the rocky shore most of the time rather than going among the corals as there's hardly any spot without corals!

Diversity is also very high. Within one metre square, I could easily find at least 8 species of corals!

And that includes several of these free-living mushroom corals too.

And on the underside, there're these brightly coloured corals (probably Tubastrea sp.) which doesn't need sunlight to survive, as they do not have zooxanthellae, the symbiotic algae which the usual sun-loving corals have.

Other than corals, there were plenty of other things to look at too, such as the graceful jellyfish. However, while they are nice to look at, they are definitely not nice to touch, as they can give a painful sting.

I also found several of these pizza anemone (Cryptodendrum adhaesivum) among the rocks and corals. The one above even has a pair of anemone shrimps on it!

But what got us really excited was this little seastar which we've not seen before. We found it under a rock, and till now we're still not sure of its ID.

ST spotted this unidentified synaptid sea cucumber among the seaweeds in the lagoon. Other sea cucumbers we saw include the black sea cucumber (Holothuria leucospilota) and the stonefish sea cucumber (Actinopyga lecanora).

Raffles Lighthouse is also a great place to spot feather stars, and we saw lots of them.

Here's another on a colony of Psammocora corals.

This birght red one has a little shrimp on it.

There were quite a few burrowing giant clams (Tridacna crocea) too. (Update: Did some checking up and realised that this might be T. maxima instead. A pity I didn't take close-ups of the sides.)

Every year I went to Raffles Lighthouse, I'll visit this giant clam. Had previously thought that it's a fluted giant clam (Tridacna squamosa), but taking a closer look I notice it didn't have the enlarged flutes usually found on this species. Could it be a Tridacna maxima then? Thought the shell certainly resembles the T. maxima specimen we have in the museum.

RH spotted this pair of mating octopuses.

The Arabian cowrie (Cypraea arabica) is probably the only large cowrie that was still regularly spotted on our southern shores. Been hoping to find a tiger cowrie, but so far my other friends have only seen it while diving.

We found several spider conches (Lambis lambis) too!

And I lost count of the number of giant top shells (Trochus niloticus) I found among the rocks on the rocky shore.

LK spotted this pretty seahare (Aplysia dactylomela) in the lagoon.

Some how there were not many nudibranchs around. Only spotted a few black phyllid (Phyllidiella nigra)...

...and a few polka dot nudibranch (Jorunna funebris).

There were many giant reef worm (Eunice sp.) out feeding, but I only managed to get one nice shot as they are very shy.

Found this crab which I've not seen on local shores before. Understand that it's a Plagusia immaculata which feeds on algae.

We saw several pretty flatworms too, including the above, a Pseudobiceros bedfordi.

Other worm we saw include a few ribbon worms, such as the striped ribbon worm (probably Baseodiscus quinquelineatus) above.

Indeed, Raffles Lighthouse is one of the last few places left in Singapore that we can still find such a high diversity of marine life, especially corals. Hopefully with its strategic position, it will remain this way for a long long time.



doomed_troll said...

great pics :) could you tell me how u got there? permission wise and stuff/

Ron Yeo said...

Hi, thanks for visiting my blog! :)

Permission must be obtained from MPA to get to the island. However, do note that it is out of bounds to normal members of the public, and usually only research groups will be allowed to go there.