23 September 2009

Still searching at St. John's Island

We're back out to search for Giant Clams for Mei Lin, and for Frilly anemones for Ivan. This time, on a side of St. John's Island that we seldom visit.
We did find a Giant mollusc there!

This is a chiton (pronounced 'kai-tun'). It must have been at least 10cm long! The chitons I've seen before were seldom larger than 1cm! The chiton belongs to a different class from snails (Class Gastropoda) and clams (Class Bivalvia). Chitons belong to Class Polyplacophora. They look like limpets with shells. I haven't done a fact sheet yet on these fascinating animals, but I guess I should now that I've met with this giant of a chiton!

We arrived at sunset and Bian and I had a quick look at the marvellous plants on the rocky shore. The matriach Xylocarpus rumphii on the shore was still looking well, although it and the other X. rumphii trees there were not flowering or fruiting. And I only now noticed a wild Kemunting (Rhodomyrtus tomentosa) clinging onto the cliff face.
We wandered quite far up this shore. The patch of Sickle seagrasses (Thalassia hemprichii) there seemed to be doing well. There's even a Black-lipped conch (Strombus urceus) happily hopping around among the seagrasses. Mei Lin also found a Spider conch (Lambis lambis). Fresh green Spoon seagrasses (Halophila ovalis) sprinkled the sandy patches among the rocks.
Alas, we didn't find any Giant clams on this shore. And we hurried back to the main shore before the tide cut off the narrow path through the enormous boulders. Meanwhile, Ivan and his team had been working very hard and managed to get a closer look at lots of Frilly anemones (Phymanthus sp.). Success!

The shores today were thick with seaweeds. Here's the three major kinds of seaweeds in one photo: brown, green and red seaweeds. The brown Sargassum seaweed (Sargassum sp.) was particularly lush today. There's also hairy green seaweed (Bryopsis sp.) and the flat sheet-like red seaweed (Halymenia sp.). The pink stuff on the rocks are also a kind of encrusting seaweed that incorporates calcium in its tissues.
A special seaweed is the tiny daisy shaped Acetabularia sp. I have no idea why, but I often see these near the White-stemmed seaweed (Neomeris sp.).
These lush seaweed growths provide lots of food and hiding places for marine life. Which makes it super challenging to explore the shore. The Ornate leaf slug (Elysia ornata) blends perfectly with the green seaweeds.
There were plenty of octopuses on the shores. And they can change their colours and body texture to match their surroundings. James saw a really really TINY octopus!
While we didn't see any Giant clams, I did see a small scallop (Family Pectinidae). We need to sneak up to this bivalve as it has 'eyes' around the edge of the shell opening. It will clam up rapidly when it detects danger.
For some reason, I keep seeing Saron shrimps! It was a bit of a challenge to photograph this little fellow in rather deep and ripply water.
There were a pair of these shrimps!
Also a delight to encounter, as the very shy Coral ghost shrimps (Glypturus sp.) which build large smooth-sided burrows in solid coral. Often, all I'd see are the tips of their orange pincers. But I had a good look at this one before it slid away into the burrow.
The crustaceans were giving me the run around. I came across this large branching Acropora coral (Acropora sp.). It was still submerged so the tentacles of the tiny polyps were still extended.
And playing hide-and-seek, deep among the branches of the coral was a tiny little orange crab, and a pair of little green shrimp-like animals. I only got glimpses of them. They moved rapidly in the maze formed at the bottom of the branches of this hard coral.
Not as fast moving were the tiny brittle stars that draped on the hard and soft corals on this shore.
But they were VERY small and hard to photograph.
Much larger were the many different crabs found on this shore. Clockwise from left: there were lots of swimming crabs (Family Portunidae), red egg crabs (Atergatis integerrimus), this odd crab with black tipped pincers which might be a Leptodius sp., and a tiny moon crab (Ashtoret lunaris).
There were a lot of long black sea cucumbers (Holothuria leucospilota). This particular one looked a bit different. It seems to have paler spots along the body. But I couldn't have a closer look at it as it retracted into its hiding place under the rock.
The most endearing animal on our shores must be the Land hermit crabs (Coenobita sp.) that got busy on the shores as soon as it was dark. But no matter how cute they may seem, we shouldn't take them home. We can't look after them as well as they can, on their own, on the shore where they belong.
Most of the hard corals seemed to be in good shape. I only saw one bleaching colony, which looks like it is affected by a change in the level of sand in the lagoon as it is bleaching at the base.
Much earlier before sunset, I had a look the ship that grounded at Sebarok Beacon.
The accident site is near the Sisters Islands, here in the foreground with the ship in between the two islands.
I was talking to our skipper about this and he said they will first have to remove all the containers on the striken ship before patching up the hole and trying to float it out.

The rest of the team saw lots of flatworms, tiny nudis and other amazing creatures. See their blog posts below for more photos and stories.

I also saw lots of fishes! While we didn't get to find any Giant clams (yet), Ivan did have a successful trip, and we saw lots of other marine life. It was a tiring trip but good to see that the shore is well.

More blog posts about this trip

1 comment:

  1. That chiton really looks huge! I'm more used to seeing chitons smaller than my fingernails, but this one is stupendously humongous.



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