08 December 2009

Tanah Merah: stars, slugs and snails

There's lots more to Tanah Merah than just fishes.
Chay Hoon found this tiny feather star among the seaweeds there!

The Common sea stars (Archaster typicus) are still plentiful on some parts of the shore.
Although Kok Sheng and I looked hard for special sea cucumbers, we didn't find any today. I also didn't come across any other echinoderms.

Kok Sheng spotted this Plain sea anemone whose identity remains unknown. We affectionately called it 'Bob'. This one had an orange body column. Later on, I spot another one with the usual bluish-grey body column.
There were also a few Haddon's carpet anemones (Stichodactyla haddoni). And I saw one Frilly sea anemone (Phymanthus sp.) in the sandy area.

There were a lot of Ornate leaf slugs (Elysia ornata) on the shore. This was a pair, one larger and one smaller. Hmm, wonder what is going on.
And there were three of them here, together, among some mucus-like stuff. Were they laying eggs?
Another cute little slug that Chay Hoon has taught us to look for are these Costasiella sp. which are found on Solitary fan seaweeds (Avrainvillea erecta). I finally manage a better photo of one. It has a cute little 'face'.
The shores were full of creeper snails (Family Cerithiidae) as usual, as well as lots of little Dubious nerites (Clithon oualaniensis). And among them, these strange snails. I don't know what they are.
In deeper water, Kok Sheng spots this Lined moon snail (Natica lineata).
Strangely, I didn't see many Gong-gong (Strombus canarium) as I usually do. Alas, we also didn't find any special burrowing snails.

On the rocks, there are more snails. Kok Sheng finds two Firebrand murex snails (Chicoreus torrefactus).
I also find several Dolphin snail shells (Angaria delphinus) but they hung on real tight to the rock and refused to let go. So I couldn't take a photo of their pearly underside.

A special find was this half of a dead Hammer oyster (Malleus sp.). Here you can see the 'teeth' on the long hinge of the two-part shell. I wonder where the living ones are? Tucked among the big boulders? Hmm.
There were also several Velcro crabs (Camposcia retusa) on the rocks.
The sandy pools were teeming with swimming crabs (Family Portunidae) of all kinds, and squadrons of Ghost crabs (Ocypode ceratophthalmus) patrolled the higher shores. I also saw one Floral egg crab (Atergatis floridus) and a little hairy crab (Family Pilumnidae). There were lots of tiny hermit crabs all over the shores, and a few Striped hermit crabs (Clibanarius sp.) but I couldn't find any Spotted hermit crabs (Dardanus sp.) on this trip.

There were also lots of blue-tailed penaeid prawns, and I saw a snapping shrimp snap at a much larger swimming crab, which promptly backed away!

A special encounter was my first sighting of a Coastal horseshoe crab (Tachypleus gigas) on this shore.
When I gently turned it over to have a look at its underside, it pointed its sharp tail towards me. This must be its way to defend itself from predators who might try to get at its delicate underside.
The tail of a horseshoe crab is not poisonous, and it doesn't stab people unless you get too close to it. And we shouldn't lift the animal by its tail as it might break off. The tail is used by the horseshoe crab to turn itself over (which it promptly did), and also as a rudder when it is crawling along the bottom of the sea.

What a nice surprise to bump into Eugene! He and his hardworking volunteers are setting up equipment to find out more about the seagrasses here. It's good to know that proper scientific work is going on to learn more about this shore.
Yes, there's lots of seagrasses on this shore. Not just lots and lots of Spoon seagrass (Halophila ovalis), but we also saw two patches of Ribbon seagrass (Cymodocea rotundata).
There was also a patch of Sickle seagrass (Thalassia hemprichii).
And also a small patch of Needle seagrass (Halodule sp.). We couldn't find the small clumps of Tape seagrass (Enhalus acoroides) that we saw on previous trips.

Eugene pointed out to us where a 'landslide' had occured earlier in the month. A wide swathe of shore was buried under sand that slid down from the high shore. Possibly due to the torrential rain. This stretch was smooth and free of seagrasses and creeper snails. Although I saw signs of burrowing crabs. It will be interesting to see how life takes back this sandy stretch over time.

Our shores are constantly changing and always interesting and important to visit regularly.

We also saw lots of fishes!

Other posts about this trip

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