08 September 2014

Octopus Garden at Sentosa

Under the full moon, a small team checks out Sentosa's natural shores at Tanjung Rimau. It's the last few days of predawn low spring tide for the year!
We check the impact of the security barrier on the shore, look out for coral bleaching and did the usual health check of the shore. Sentosa is still very much an octopus' garden!

There is still a bloom of Bryopsis seaweed. This is not normal. Usually, around this time of the year, the Sargassum seaweed bloom replaces the Bryopsis seaweed. I wonder what is going on. But as usual, this bloom is teeming with life. There were lots of little Reef octopuses slitthering through the Hairy green seaweed.
And of course, an explosion of Bryopsis sea slugs. These slugs suck the sap of the seaweeds and eventually look like the seaweeds in shape and colour!
There are all kinds of crabs of all shapes and sizes.
This Arrow-head crab had stuck Sea grape seaweeds on its head!
Also amphipods (body flattened sideways) and isopods (body flattened downwards).
Countless Little red-nose shrimps, as well as small snapping shrimps and little hermit crabs.
 Two kinds of flatworms: the Blue-lined flatworm and Blue-spotted flatworm.
Also lots of bristleworms of all sizes, squirming through the seaweeds.
Octopuses can instantly change their body colour and texture to match their surroundings!
There was also a small clump of Ridged corallimorphs.
Tucked under a purple coral was this brightly coloured Mosaic crab, the most poisonous crab in Singapore! I also spotted one Red egg crab.
Animals in the rubbly area are very well camouflaged. Like this swimming crab and a False scorpionfish (top right corner).
As usual, the Haddon's carpet anemone has a pair of Five-spot anemone shrimps, the mama shrimp is bigger and more boldly patterned than the papa shrimp.
For the first time, I saw this Tiny carpet anemone shrimp in the same anemone as the Five-spot anemone shrimp!
On the rocky shore, Victor spotted this gecko. Nick Baker's awesome EcologyAsia website has lots of info about lizards and geckos of all kinds. But I'm not too sure what this is. Thanks to Marcus Chua who confirmed that it is the Maritime gecko!
I finally find a Toothed top shell snail with its body showing. It also has fine lines, somewhat like the Nerite snails.
The corals on this shore suffered badly during the mass coral bleaching event in 2010. So I was glad to see that there wasn't much bleaching today, and that there were many small coral and leathery soft coral colonies in the short stretch of shore that I checked. I saw many small colonies of Pore corals and they were all nice and brown. I only saw one small colony of Disk coral and while it was not bleaching, it didn't look very healthy either.
Most of the corals on the shore were small colonies of Favid corals. And I only came across two that were partially bleaching.
There were a few small colonies of Leathery soft corals of various kinds. Only one was somewhat bleaching.
I saw several kinds of sponges too.
I was very excited to see a nice small patch of Sickle seagrass! Although Siti reported seeing this species on Sentosa in Apr 2012, this is the first time I'm seeing them for myself. The Tape seagrasses are all long and lush and not thickly covered in epiphytes.
A closer look at the Sickle seagrass, with tiny octopus.
I saw many female Tape seagrass flowers but only one had petals, which usually only last one day. Perhaps they all just bloomed yesterday? I didn't see any tiny white male flowers floating on the water though.
There were also patches of small Spoon seagrasses. Seagrasses provide shelter for small and young animals and are thus an important nursery in the sea.
The tide turned before sunrise, so we also checked out the shore behind Underwater World Singapore. Alas, we had to leave well before sunrise.
I didn't come across any Frilly sea anemones which are usually abundant on this shore. One animal we are glad NOT to see is the Stonefish. We have had a Stonefish incident one this shore before, so we are very careful when exploring this shore.

The long line of blue drums are still there. These are part of a floating 'security barrier' installed in 2012. I only managed to look at a few of those nearer the shore. Compared to Pei Yan's last check in Aug 2013, none of the drums are broken, and it appears they have been rearranged so that the drums no longer bash against the rocks. The line of drums are also straighter. Pei Yan has been documenting the changes and impact of these drums.


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