12 May 2009

Tanah Merah: a total surprise!

Kok Sheng has persuaded us to explore a shore at Tanah Merah early this morning. In contrast to yesterday's natural rocky shore, this shore is man-made. A long rock wall on reclaimed land with a shallow, sandy area behind the wall leading to a beach.I had visited this shore many years ago when I first started exploring. At that time, it was almost completely devoid of life. So I was quite skeptical.

As soon as I stepped foot on the shore, I realised every inch beneath the low water mark was covered with life. There were bazillions of Zoned horn snails (Batillaria zonalis). I have read that "they can reach densities of hundreds of snails per square metre". I believe it now. This is the first time I've ever seen that many of these snails in one location.
And regularly dotting the vast shore were coiling heaps of 'processed sediment' made by the Acorn worm (Class Enteropneusta).

OK, that seemed a good start from the totally bare sand I saw years ago. Then Kok Sheng points out there's also Dubious snails on the shores. I had to look really closely before I saw them. They are miniscule and most were well spaced out on this shore.I love these tiny snails! Dubious nerites (Clithon oualaniensis) are listed as 'Vulnerable' in the Red Data Book which says "populations along the original shores have been wiped out by reclamation." Well, they were certainly doing well on Tanah Merah!

On the sand were tiny coils of sand collars, egg masses of Moon snails. Were they laid by the Pink moon snail?
And James saw one Pink moon snail with its foot out, while I got this shy one which hid behind its operculum with rings of ridges.

I got a bit snail crazy this morning, especially after seeing the empty shells of these interesting snails.
Top white shell is probably of the Frog snail (Bufonaria sp.), the one on the left is probably of a Bonnet snail (Family Cassidae), while the one on the right I have no idea! I also saw an empty shell of a Rare-spined murex (Murex trapa), and a Cone snail! But alas, though I looked and looked, I didn't find living specimens of these snails.

These empty shells were put to good use by all kinds of hermit crabs including the Striped hermit crab (Clibanarius sp.), the tiny Tidal hermit crab (Diogenes sp.) and even tinier Banded hermit crab.

James made up for my sad effort at finding snails in the sand. He found special snails on the rocks! He found this humungous snail on the rocks. It was covered in encrusting lifeforms.
From the general shape and the thin operculum, it seems to be a member of the Family Trochidae.
James found yet another special drill on the rocks! This one seems to be Chicoreus torrefactus a member of Family Muricidae. According to "A Guide to the Common Seashells of Singapore" by Tan, K. S. and L. M. Chou, this snail is found in sandy areas near reefs and feed on clams.

Are there reefs nearby? Kok Sheng pointed out some small hard corals growing on the rocks. They seem to be mostly Favids (Family Faviidae)
This one has tiny hexagonal corallites.This one also has hexagonal corallites that are 'toothed'.
Here's one with large ring-shaped corallites that resembles beans.While of course, there's the hardy Zebra coral (Oulastrea crispata).While often mistaken for the polyps of a hard coral, these are actually colonial anemones or zoanthids, probably the Button zoanthid (Zoanthus sp.).This rock was coated in really tiny zoanthids. I have no idea what they might be.For some reason, there were no Banded bead anemones to be found on the rocks. In fact, there were very few anemones on the shores aside from a few of the Peachia anemones (Peachia sp.) above. I'm a bit of a nem nut so I was looking out for them. This is strange.
Settled on rocks, ropes and other hard objects were many large fan worms (Family Sabellidae).

On the sandy areas were many Flower crabs (Portunus pelagicus).
Most were tiny little ones, and when I saw this large pale one, I almost missed the darker crab behind it. A closer look reveals this crab has just moulted and the pale 'crab' is its discarded skin! In the pools of water were also other swimming crabs (Family Portunidae) such as Thalamita sp. There were also burrows of what seemed to be Soldier crabs (Dotilla sp.) and on the high shores those of Sand bubbler crabs (Scopimera sp.) and large burrows of Horn-eyed ghost crab (Ocypode ceratophthalmus). I was too lazy to stalk the crabs for a photo of them.

Of course the pools were teeming with little gobies of all kinds.
The one on the left is probably an Ornate lagoon-goby (Istigobius ornatus) and the one on the right is probably a Common frill-fin goby (Bathygobius fuscus).James found this flatfish! It is probably the Large-tooth flounder (Family Paralichthyidae) as its eyes are on the left side and its tail is well separated from the anal and dorsal fins.
But the best fishy find was by Mei Lin who spotted this Long-horned cowfish (Lactoria cornuta) in a pool of water. Next to it was a filefish!We also came across about 30-40 Common sea stars (Archaster typicus) many in pairs getting ready to procreate. Go Stars! As Kok Sheng noted, this is the first time we're seeing these stars on the mainland! Wow!
There were also two patches of bedraggled Tape seagrasses (Enhalus acoroides) near the rocks. But strangely, I didn't see any Spoon seagrasses (Halophila ovalis) which are often seen on even the most beat-up of our shores. There were small patches of various common seaweeds, but not a lot of them.

Kok Sheng shares more about these and other finds on his blog.

Kok Sheng and Mei Ling very bravely went to explore a reefier part of this shore. I decided not to risk life and limb and stayed on the safe flat shore. They soon came back all wet and slimy but with lots of gorgeous photos of magnificent reefs! Who would have imagined such a thing at Tanah Merah!

Alas, the light of day reveals the usual marine litter that washes up on many of our shores.
We are quite intrigued by the diversity of marinelife found on these shores. I'm quite sure these are recently settled particularly since I saw almost nothing on my trip many years ago. Does this demonstrate the power of nature to recover? Imagine what we might have if we just let nature take its course?

These shores and rock walls are clearly man-made. The location of the Ferry Terminal is circled in yellow in the current Google Earth map of Singapore.The Ferry Terminal was first set up in 1995 on reclaimed land. As can be seen from these Landsat photos from the US Geological Survey page on Earthshots: Satellite Images of Environmental Change (which by the way has a great account of the changes, go read).

More blog posts about this trip


  1. Looks like Singapore's mainland shores still have plenty of surprises.

    And I guess we can't say that Labrador is our last mainland reef anymore.

  2. Thanks for sharing, I cannot wait to explore the place...

  3. I think you have just destroyed the place as people will now go there in droves and destroy whatever fragile diversity of the place.

  4. It is a dilemma. Should we keep a nice shore to ourselves? Or share it so that others can see it for themselves? From my experience at Chek Jawa before deferment, I believe there is much that can be gained from having ordinary people see our shores for themselves.

    The alternative is to lose a good shore to development, with very few having experienced it for themselves before it was gone. For a reclaimed shore, the chances of this happening is quite high.



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