21 September 2009

Semakau at sunset

Our first evening low tide trip for the year, and Pulau Semakau still surprises even after lots of field trips there for the Semakau Book.
Sijie spotted this amazing creature!

It was small, about 10cm across. It looks like a small Fire anemone (Actinodendron sp.)! Because of the white stripes on the oral disk, and the typical structure of the fat tentacles. It's the smallest Fire anemone I've seen!
We also saw several larger anemones, such the Giant carpet anemone (Stichodactyla gigantea) some of which had anemonefishes but were too shy and well hidden. Semakau also has an abundance of Bubble tip anemones (Entacmea quadricolor) and this one had a Tomato anemonefish (Amphiprion frenatus)! But we could only see the tips of its orangy red fins. We left all the anemonefishes alone as they belong in their anemones.
Another Semakau special which is sometimes mistaken for a sea anemone, is the Sunflower mushroom coral (Heliofungia actiniformis). This giant solitary polyp has very long tentacles and a single central mouth. But like other hard corals, it has a hard skeleton.
While this is NOT a mushroom coral but a colonial hard coral: the Torch anchor coral (Euphyllia glaberescens) which so far I've only seen on Hantu and Semakau. This is a colony of little polyps with thick, white tipped tentacles.
And here's another hard coral that so resembles a sea anemone that its common name is Anemone coral (Goniopora sp.). But it is NOT a sea anemone. It is colony made up of many little polyps which have a long body column topped by tiny tentacles. They come in pretty pastel shades of pink and lilac.
We also saw a lot of Brain corals (Family Mussidae) in all kinds of shapes and colours.
We also saw nice colonies of this coral which I think is a Favid coral (Family Faviidae).
And it's always great to see the Galaxy coral (Galaxea sp.) with its pretty star-shaped corallites.
Other corals seen include the Carnation coral (Pectinia sp.), Disk corals (Turbinaria sp.) of all kinds, and of course, plenty of Pore corals (Porites sp.) and Favid corals (Family Faviidae).
The corals on Pulau Semakau seemed generally alright. And those found bleaching, like the one above, were colonies that had been overturned. There were a few, but not many of these.

The reefs are home to all kinds of animals. Sijie spotted this crab. I'm not too sure what it might be. There were also lots of Hairy crabs (Family Pilumnidae), Red egg crabs (Atergatis integerrimus), and swimming crabs (Family Portunidae).
What a treat to find a seahorse!
This remarkable animal is a fish! The ones with the yellow and black tails are believed to be the Hippocampus comes also called the Tiger-tailed seahorse. I only noticed the seahorse because she was busy feeding, sucking up little titbits from the water with her tube-like snout.
It was Sijie who noticed her partner nearby. He was keeping very still and looked just like the encrusted sponges around him.
As the sunset, we started seeing Toadfishes (Batrachomoeus trispinosus) in the pools as they came out of hiding.
As well as octopuses! A Master of Disguise, the octopus is rather hard to spot until it moves.
These photos are of the same little guy. It often spread out its arms and used the webbing between the arms as a kind of net to enclose a little pile of rubble. It changed colours rapidly as it moved about. Octopuses are fascinating to watch!
We also came across some nudibranchs. The black-trimmed Glossodoris atromarginata and the polka-dotted Jorunna funebris are commonly seen on our shores. Stephen also saw the orange spotted Gymnodoris rubropapulosa.
Another very common mollusc on Pulau Semakau are the Noble volutes (Cymbiola nobilis). Today we saw a little one on top of a larger one that was nearly buried in the sand. What's going on? Wow, there's so much more to learn about our shores.
As dark settled on the shores, many enormous spotted black flatworms (Acanthozoon sp.) slid out of hiding. These animals can be as big as the palm of your hand!
And just as we were leaving, Sijie spots a Knobbly sea star (Protoreaster nodosus), with six arms! These large sea stars are also common on Pulau Semakau, although not as plentiful as at Cyrene Reefs.
Earlier in our trip, we stopped by to have a look at the Cryptic sea stars (Crypsasterina sp.). These well hidden and camouflaged sea stars are so far only found on Pulau Semakau.
The purpose of the trip to Pulau Semakau was for Sijie and Oliver to check out the shore for an upcoming event for the Scouts. We were literally scouting the shores...haha.
We found a massive bunch of driftnets draped out on the shores.
And wound around some mangrove trees. As well as abandoned fish traps here and there. This is something that can be dealt with by the Scouts.
Cleaning up the shores is a never ending task.

Meanwhile, the rest of the team were exploring another part of Pulau Semakau and helping Mei Lin with her Giant Clam project. Read their blogs to find out more about what they saw.

It was a pleasant evening trip, with great weather! AND a ride in and out by the very kind NEA officers. That was most unexpected and very much appreciated.

More blog posts about this trip

More about Pulau Semakau on the wildsingapore website.

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