01 January 2011

More mangroves at Kranji in the New Year

Our first trip for the New Year is of course back to Kranji to check out the mangroves there. It's high tide when we arrive!
So we explore the edges where it's drier and come across some surprising mangrove trees!

How nice to come across a few Gedabu (Sonneratia ovata) which are listed as Critically Endangered. It's my first time seeing such nice tall Gedabu trees. They were fruiting! With some fallen fruits too! I had seen signs of them on my earlier visits but didn't come to this side and thus missed them. That's why I feel it's important to check up on our mangroves over several trips.
Brandon showed us this very tall tree. It doesn't have much foliage and is leaning over rather precariously. Could it be Berembang (Sonneratia caseolaris)? This kind of tree is also listed as Critically Endangered.
A look at the leaves high in the canopy. It was hard to look for fallen fruits as the tree was leaning over the thicket of plants that grow at the edge of the mangroves.
I usually come across signs of the identity of a mangrove plant by looking down for fallen flowers. There were lots of these odd bits of flowers. Later on Brandon suggested they might be Teruntum (Lumnitzera sp.). I think he's right! Dr John Yong mentioned that this area is known for its large and old Teruntum trees.
Of course we had a look at the Bakau mata buaya (Bruguiera hainesii). I still can't get a good shot of the flowers. Brandon managed to take a photo of a propagule on the tree! But we didn't find any fallen propagules today.
There were still some fallen B. hainesii flowers on the ground. But not as many as before. This one still had bits of petals on it. It's just sheer luck that I happened to stumble on the area when the tree was blooming so massively that even a blind person like me couldn't miss the flowers.
Here's another kind of Bruguiera, Tumu (Bruguiera gymnorrhiza) may have a pink calyx, but sometimes also pale or yellow. The calyx clasps the propagule, instead of sticking out as in Bruguiera hainesii. This kind of tree is still considered rather common. But I still appreciate our common mangrove trees. Tumu can be quite pretty especially when flowering and with well formed buttress and knee roots.
The most commonly encountered Bruguiera is Bakau putih (Bruguiera cylindrica). The pointy parts of the calyx bend all the way back away from the propagule in this kind of tree. I must say I am often frustrated by this tree when looking for the rarer Bruguiera. Because most times, the suspicious tree turns out to be Bruguiera cylindrica!
I also came across a small Tengar merah (Ceriops zippeliana) growing in a sunlit opening in the mangrove forest. This kind of tree is listed as Endangered and it was first discovered in Singapore in 2009 by Dr Yong and his colleagues.
There was a large and beautiful Mangrove cannonball tree (Xylocarpus granatum) with many large bowling ball sized fruits hanging in the canopy. On the ground, some fallen fruits and even some seeds (they are irregularly shaped and emerge from the round fruit). Although this tree is considered common, I still think large ones are quite magnificent to encounter, with lovely patchy peeling bark and lush green leaves.
The large tree has wonderful graceful snake-like buttress roots! I have read about this in mangrove ID books and it's nice to finally see such well-formed roots.
In the shady areas there seemed to be lots of Wax plant climbers (Hoya sp.). But alas, I couldn't spot any that were flowering. Yet another reason to regularly check up on our mangroves. Many of our mangrove plants can only be identified by their flowers or fruits.
As the tide fell, we spend most of the time slowly checking out the centre of the mangroves where there are lots of awesome mud lobster (Thalassina sp.) mounds! This kind of habitat is rather rare in Singapore.
How lovely to come across some Black-mouth mangrove nerites (Dostia cornucopia). When the icky mud is removed, we can see the pretty shell pattern! The underside is black.
It looks like they are laying eggs! See the little round white egg capsules?
There were many very large Lined nerites (Nerita articulata) on the tree trunks.
I'm kind of addicted to mangrove onch slugs now. And can't resist taking photos of them. Their undersides are often in different colours. This one looks like what I call the Long onch.
There were also many of these Chut-chut snails. The Red chut-chut (Cerithidea obtusa) has a red body and white mouth. The Black chut-chut (Cerithidea quadrata) has a dark body and dark mouth.
And in some parts, the ground is teeming with little Red berry snails (Assiminea sp.) which I just can't resist photographing because they look so cute.
All kinds of different spiders lurk among the leaves. The little white furry one is my favourite mangrove spider, the Heavy jumper (Hyllus diardi). I'm not too sure what the other one is.
There are all kinds of crabs on the mud lobster mounds and in the mud. At first glance, they may seem drab and boring. But a closer look reveals they can be quite colourful! The top row are probably Tree-climbing crabs (Episesarma sp.) while the lower row are Face-band crabs (Perisesarma sp.).
I saw this skink scuttling among the mangrove roots. I didn't manage to get a photo of the entire animal. Looking at Nick Baker's awesome Ecology Asia page on skinks, I can't really figure it out. It's probably NOT the mangrove skink which does not have keeled scales, while the one I saw does have keeled scales. See also the Mangrove skink in the Guide to the Mangroves of Singapore.
Brandon showed us some strange green slugs! Then Chay Hoon found more. And we discovered they were almost everywhere! Gathered in large numbers in pools of water. In the murky gloom, it's easy to mistake them for fallen leaves. They were so flat, they do resemble flatworms. But Chay Hoon showed me how they do look like Leaf slugs when they 'unflatten'.
Why are they grouped together? Perhaps they were mating? But we didn't see any white structures sticking out of their necks, like we've seen with the Ornate leaf slug (Elysia ornata).
Chay Hoon checked up the id on Bill Rudman's awesome slug site. It seems to be Elysia bangtawaensis which is found in mangroves and have been reported to be sighted elsewhere in large numbers too. I've never seen this before.

So much to discover in our mangroves!


  1. The skink appears to be a common sun skink.

  2. Thanks Ivan! Yes, I didn't think it was a mangrove skink. Sigh.



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