28 December 2008

Vertebrates of Pulau Semakau

The Semakau Book team was out yesterday evening with the companiable Vertebrate Group Team led by Subaraj Rajathurai. I had a wonderful trip with the good humoured and delightful team members. And I sure learnt a lot from them.
It was a glorious blue-sky day and after gratefully getting a ride out with James from NEA, we headed off to find things with backbones.

Well, actually, the Vertebrate Group did that difficult job on the high shore.While Serin and I escaped to the low shores to check out the creatures without backbones.Among the first creatures we came across was this small Noble volute (Cymbiola nobilis) at an empty Noble volute egg capsule. I'm not really sure what is happening here.The snail seems too small to be mature enough to lay eggs. Those I've seen laying eggs were a lot bigger. But it also seems too large to have emerged from the egg capsule. I'm not too sure either whether the snails emerge from the egg capsule as miniature adults. Hmmm. There sure is a lot to learn about our marine life!
Serin is great at spotting marine life and he finds a total of three Spider conch snails (Lambis lambis)! Although large, they are not easy to spot as the upperside is covered with encrusting stuff.But the underside is usually a pretty pearly pink and orange. Snails of this family have endearing eyes on long stalks. They also hop! Using their knife-like operculum attached to a muscular foot, somewhat like a pole-vaulter.We also saw the other conch snails typically found in such ecosystems. The Gong-gong (Strombius canarium) (left photo) is among those harvested and eaten. While the Black-lipped conch (Strombius urceus) (right photo) is less often encountered.We also saw a lot of Sunflower mushroom corals (Heliofungia actiniformis)! They are easily mistaken for sea anemones, but are actually hard corals. Each mushroom-shaped animal is a giant solitary polyp that forms a hard skeleton. Here's more on how to tell apart sea anemones from large 'hairy' cnidarians. In the South, I've only seen these amazing animals in numbers on Pulau Semakau, and Pulau Hantu which lies just opposite.Peacock anemones (Order Ceriantharia) may be ho-hum to people who are familiar with our Northern shores such as Chek Jawa. But these graceful animals are not as commonly encountered on our Southern shores. So it was nice to see this white one on Pulau Semakau.

Serin has really sharp eyes and spots several squids! This one was hiding under some seagrasses.
As it zoomed off, it rapidly changed colours!Serin also spots this wriggly animal that looks like a worm or a little snake.It's the Worm eel (Muraenichthys sp.) of the Family Ophichthidae! This energetic wriggly little fish investigates every hole and crevice for prey. It has a sharp pointed tail so that it can also burrow backwards! A splash alerts us to another eel-like animal. It's a large Carpet eel-blenny (Congrogadus subducens) that slithered rapidly across dry sand to disappear into a pool and under a large chunk of coral rubble. This fish is not an eel, nor is it a snake. Here's more on how to tell apart sea snakes, eels and eel-like animals.

In a pool of water, we also spot one lonely little Razorfish (Family Centriscidae). This fish has a habit of hanging vertically, face down. In this way, it is often mistaken for a bit of rubbish. But the fish can swim horizontally, and quickly too.
It doesn't have a broken tail. The bit that is bent is the dorsal spine. This is a characteristic of razorfishes that belong to Genus Aoeliscus. Usually, these fishes are found in groups of several, all hanging head down. This poor fish may have gotten separated from its friends during the low tide. Let's hope he can find them when the tide turns. We've seen these fishes at Pulau Hantu, Cyrene Reefs and Sisters Islands as well.

It was sharp-eyed Serin who spotted not one but two of these special gobies.
It is possibly the Slender-lined shrimp-goby (Cryptocentrus leptocephalus) which I've seen on Kusu Island with a snapping shrimp.Serin shortly spots another one that had gotten stranded. After quickly taking a photo of it, we nudged it back into the water whereupon it zooms instantly into a hole. Wow! With these two sightings, I can now do a page about this beautiful fish on the wild fact sheets. Thank you Serin!And to top off the fishy sightings, we get a glimpse of a 'Nemo' look-alike. Our very own False clown anemonefish (Amphiprion ocellaris) in a Giant carpet anemone (Stichodactyla gigantea)! Earlier on, Serin also saw a sting ray!

Well, it looks like Serin has sure found a lot of vertebrates on Pulau Semakau. Fishes have backbones and are vertebrates just like us.

As the sun sets, Serin and I head back to the high shore to rejoin the rest of the Vertebrate Group. In the gathering dusk we wait on the sea wall to see if we can spot any bats that might be leaving their roosts. Alas, we didn't see any bats.

But there were lots of Spiny-tailed geckos everywhere! Almost every post on the road dividers had one. And lots of frogs too!In fact, a tiny one was seen on the road. Prompting a frenzy among the paparazzi.Here's a closer look at the cute little fellow.There were more among the rocks and the sparse vegetation next to the road.And we also saw toads (I learnt this was not a frog...ha ha, I'm terrible at anything above the high water mark). These were a lot smaller than the ones we usually see on the mainland. We also heard a chorus of frogs in the forest, and the Savannah nightjar was furiously calling in the grasslands while shore birds twittered in the marshy areas on the landfill. We made a brief foray into the mangrove edges and came across a huge sea bass as well as a gianormous mud crab and other creatures. Alas, we didn't encounter any snakes so far. Although something that slithered was spotted disappearing into the rocks by the side of the road. I was too slack to hazard the slippery sea walls. Fortunately Marcus has posted about these as well as all the other splendid sightings by the Vertebrate Group on his annotated budak blog: Croak on a Rock and Hunter in the dark and Crabby New Year.

James very gamefully joined us after dark and gave us a ride back! What a treat. My weary feet are very thankful!

We're quite excited to make more visits with a larger Vertebrate Team so we can find out more about the fascinating vertebrates on Pulau Semakau.

We had glorious weather, so lots of lovely landscape photos of Semakau were taken. As well as some less happy sightings. More in the following post.

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