20 October 2009

Evening at Changi

Our first evening trip to Changi for a long while.
Rob finds a cute little Leaf porter crab (Family Dorippidae)! This sneaky crab clings onto a leaf or other bit of debris with special legs bent over its back, while swimming with its four long feathery legs.

James and Stephen were already on the shore when we arrived. And James had found a small seahorse! The Estuarine seahorses (Hippocampus kuda) on our Northern shores are sometimes bright orange!
We eventually met up with Yue Yun as well. Today I noticed the Needle seagrasses (Halodule sp.) had spread out to cover quite a large patch. There were also lots of Fern seagrasses (Halophila spinulosa).
There were of course lots of Spoon seagrasses (Halophila ovalis). These seagrasses with rather long and pointy leaf blades and long thin stalks look suspiciously like Hairy spoon seagrasses (Halophila decipiens).
All these seagrasses make a happy home for a whole host of creatures. Tiny little fishes shelter here, where they can find food and safety to grow up into bigger fishes. I didn't see many other fishes, probably as it was still daylight for most of the trip. We see a lot more fishes during a night trip.
Echinoderms are a special feature of the Changi shores. There were quite a few of these Painted sand stars (Astropecten sp.) crawling among the seagrasses. Often with a load of sand on them. Possibly they just emerged from hiding in the sand?
The smaller Plain sand stars (Astropecten sp.) were more commonly seen in the sandier stretches between the seagrass meadows. Often detected by the star-shaped impression they leave on the sand surface.
There were a few small Garlic bread sea cucumbers (Holothuria scabra), very cute they were!
The seagrasses were dotted with red Thorny sea cucumbers (Colochirus quadrangularis) and one of these less commonly encountered Pink warty sea cucumbers (Cercodemas anceps).
We also found this Smooth sea cucumber (I think that's what it is), unearthed and rolling about in the waves.
While there were a few Ball sea cucumbers (Phyllophorus sp.) buried even among the seagrasses. But I didn't see any of the Polka-dotted sea cucumbers that Siyang identified as Holothuria ocellata. (I need to update my fact sheets).
The sea urchin season seems to be over. There were a lot of white skeletons of dead urchins, and I saw only one live White sea urchin (Salmacis sp.).
But the sand bars were teeming with large Cake sand dollars (Arachnoides placenta).
Alas, I didn't come across the special snails that eat the sand dollars. But I did see one Olive snail (Family Olividae). While Yue Yun found a large Noble volute (Cymbiola nobilis).
Other molluscs that were seen in numbers today include the Window pane shells (Placuna sp.) and Fan shells (Family Pinnidae).

There were also signs of big Moon snails (Family Naticidae)! This sand collar is the egg mass created by a mama moon snail around her shell. Using her foot she mixes sand with mucus and eggs which hardens into collar-like shape. From the size of the collar (see my size 7 foot next to it), the mother must have been quite large!
When snails die, their shells are put to good use by hermit crabs. On Changi, these borrowed shells are often festooned with sea anemones. James found this hermit crab with five small anemones on its moon snail shell!
Other anemones encountered includes this one Swimming anemone (Boloceroides mcmurrichi), clinging to the seagrasses.
And a really small Carpet anemone (possibly Stichodactyla tapetum) buried in the sand among the seagrasses.
There was this tiny cnidarian in a sandy pool, possibly a peacock anemone (Order Ceriantharia)? I didn't see any big peacock anemones.
Some other creatures that were 'missing' include the sea pens. Usually there are many of these Sea pencils, but I only saw one on this trip. It may be that they are retracted into the sand during the day?
There are all kinds of tiny creatures among the seagrasses, like this tube worm. It was very shy and I only managed to get a shot of the tippy tips of its tentacles.
As night fell and the tide turned, the crabs started to emerge. The large Spotted moon crab (Ashtoret lunaris) swimming about in the seagrasses. And several frisky Ghost crabs (Ocypode ceratophthalmus) were busy on the high shores. I didn't see as many Flower crabs (Portunus pelagicus) as I usually do.
Earlier when there was still sunlight, the shore was quite busy with families, groups of young people and other people. Many were simply having a look. Some were collecting stuff.
Much much earlier in the day, I had the great pleasure of meeting Dr Terry Gosliner. He was in Singapore for only 6 hours and squeezed out time for a dive at our very own Pulau Hantu!
Thanks to Debby (right) and Chay Hoon (left) who took the time out of their busy schedules to share our wild reefs with him! I heard they had an interesting dive despite the uncooperative currents.

Dr Terry is author of some of my favourite and essential guides to marine life such as "Coral Reef Animals of the Indo-Pacific: Animal Life from Africa to Hawaii Exclusive of the Vertebrates" and "Indo Pacific Nudibranchs and Sea Slugs". He is particularly well known among nudibranch enthusiasts (see Nudi Pixel's write up on him).
It's wonderful that Dr Terry took the time to look at our humble shores.

Meanwhile, Debby had an extra busy day not only with work and school and the dive, but also setting up the Hantu Blogger booth at the ASEAN Conference on Biodiversity which starts today. Sigh, I didn't even find time to peek in there yet.

MORE TRIPS coming up!

Other posts about this trip

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