13 January 2009

Mudlobsters and reefs of Pulau Semakau

A small hard-core Semakau Book Project team was back on Pulau Semakau!
Alas, for another wet day (we are convinced Eric is the rain-maker). But despite the drippy weather, more exciting encounters!

Marcus and I managed some quick photos of the mangroves that Dr Jean Yong showed us the day before. But soon, we got hit by the weather.

Too wet to wander and the tide still high, Marcus and I decided to try to find the patch of mangroves in the middle of the island. A bit of mild bush whacking got us to a wonderous site full of mudlobster mounds!!Narrow mangrove streams threaded through small firm mounds crawling with crabs little and big, all quite unafraid of people. It got quite thickly overgrown and we didn't push very far in. Besides which, the mozzies were really sucking us dry. We must certainly come back with Dr Jean Yong and the Mangrove Team and hopefully find some other sexy strange and rare mangrove plants!!

Fortunately, the rain lightened as the sun set and tide fell. But the wind was mighty strong. If I didn't take off my poncho, I was sure I would fly like a kite.

Pulau Semakau's reefs are humungous and the good stuff is spaced out far apart. There's of course, hard corals on the reefs. In all kinds of shapes and colours.Left: possibly a branching Pore coral (Porites sp.) Right: possibly a Favid coral (Family Faviidae).
Left: A pretty greenish-blue Carnation coral (Pectinia sp.) tucked among the coral rubble. Right: A beautiful bluish yellow Cauliflower coral (Pocillopora sp.).
This is the delicate Lettuce coral (Pavona sp.) which is not commonly seen on our shores. How nice to see this beautifully formed colony on Pulau Semakau.
Left: A glow-in-the-dark Favid coral, here's more about why some corals are flourescent. Right: Galaxy coral with the polyps expanded thus hiding their hard skeletons.

We also saw several Torch anchor corals (Euphyllia glaberescens), which so far I've only seen on Pulau Semakau and Pulau Hantu. Other hard corals that were commonly seen included Brain corals (Family Mussidae), Maze corals and Hexagonal corals (Family Faviidae) and Sandpaper corals (Psammocora sp.)
The polyps of the Anemone coral (Goniopora sp.) have long body columns so the colony is often mistaken for an anemone. But it's a hard coral. Chay Hoon told me a nudibranch is associated with this coral that looks just like the polyps. So I looked carefully, but alas, none that I saw. We need Chay Hoon with her macro-mode eyes to find them!It took me a while to figure out these cute little animals. While they do look like small sea anemones, they are actually hard corals. They are small Sunflower mushroom corals (Heliofungia actiniformis). When these animals are young, they remain attached to a hard surface.As they grow up, they break free and are free-living, i.e., unattached to the ground! Besides being mobile hard corals, the other fascinating thing about these animals are that they are gianormous polyps! Instead of being a colony, each Sunflower mushroom hard coral is a single large polyp! With their long tentacles, it is easy to mistake them for sea anemones. Here is more on how to tell apart 'hairy' cnidarians with long tentacles.

Here is one such sea anemone, that is large and appears 'hairy' due to its many long tentacles.This is my first time seeing the Magnificent sea anemone (Heteractis magnifica) on Pulau Semakau! It is indeed large and magnificent. I've so far only seen these anemones on Kusu Island and Pulau Hantu. Alas, in the wind and rain, I couldn't find any fish or shrimps living in this anemone.

I also came across one Giant carpet anemone (Stichodactyla gigantea) and I thought I saw a wriggle of an anemonefish but it was just too wet to look for it.

Marcus came across a large sea anemone which looked quite different from anything I've seen. It might be the Snaky anemone (Macrodactyla doreensis) or something else entirely! [Afternote: It turned out to be Heteractis crispa which was thought to be locally extinct! See Marcus' The Annotated Budak blog for more details!}

We also came across the Wriggly star anemone (yet to be identified) and lots of Frilly sea anemones (Phymanthus sp.)

A good reef provides shelter and food for a wide range of marine life. Splashing about in the murky shallows and deeper waters were all kinds of fishes. Too fast for me to photograph.

At sunset, Eric, Alicia and Edward joined us on the shores and we spotted more things with more pairs of eyes.

Knobbly sea stars (Protoreaster nodosus) are always a delight to encounter. There are, however, not as many of these stars at Pulau Semakau compared to Cyrene Reef.The sea star on the left photo was gigantic. It must have been 30cm in diameter. A more normal sized one was later seen, both in the coral rubble area.As we explored the seagrass area on the way back, we came across a small one nestled among the seagrasses and seaweeds.

Edward and Eric found this enormous Eye-spotted sea cucumber (Stichopus ocellatus)! It too seemed to exceed 30cm. But Eric who dives in all kinds of exotic places, says he's seen much bigger ones. We also saw several very large Garlic bread sea cucumbers (Holothuria scabra). Both these sea cucumbers are listed on our Red List of threatened animals of Singapore, so it's good to see them on our shores.

In a pool, we saw two large cuttlefishes or squids (we couldn't tell in the murky waters) zooming about, puffing ink clouds here and there.

Everyone loves nudibranchs and Pulau Semakau's reefs seldom disappoint.The clownish orange-spotted Gymnodoris sp. is quite commonly encountered on Pulau Semakau. It is also seen in nearby reefs such as Pulau Hantu and Pulau Jong. This creature eats other nudibranchs! Chay Hoon has documented this amazing encounter of a small Gymnodoris that seems to be trying to eat a much larger nudibranch!

Another commonly seen nudibranch is the Polka-dotted nudibranch (Jorunna funebris).This one has its front end stuck to a blue sponge. Is it eating it? These nudibranchs are believed to eat sponges. Hmmm...

Eric also saw a Glossodoris atromarginata in the seagrass meadow. An odd place for it to be.

For me, the find of the day was this beautiful flatworm with fine lines.Chay Hoon had shared a photo of one seen on Pulau Semakau but this is my first time seeing it here. I don't see this flatworm often, so it was a great opportunity to take a good photo of it. And for some reason, the wind and rain stopped just for a few moments. Enough time for me to get a few shots of it!

According to Leslie Harris of the Natural History Museum of Los Angeles County, who earlier kindly commented on my worm photos, this is probably NOT Pseudobiceros fulgor as the arrangement and size of the lines and the margin are too different. On the other hand, it does not match anything else so far commonly recorded elsewhere.

Marcus saw lots of other fantastic stuff including a feather star. We'll have to wait a while for him to blog as he catches up with more interviews and briefings to NEA for the Semakau Book.

All too soon the tide turned and it was time to make the long trek home. It was extra hard walking back against a super strong, constantly roaring wind that literally made us deaf. I suggested we should walk back in a V-formation to save energy...haha. Later on I found out strong winds had cause much damage in some parts of Indonesia.

It's been exhausting doing Pulau Semakau two days in a row. But always exhilarating to explore the shores!

Two more days of low spring tide!

1 comment:

  1. Yes, two more days! I don't know whether to be sad or relieved that these low tides don't occur more often!

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