Semakau Trips Over Last Weekend

Last Saturday and Sunday, I was back on Semakau for a Project Semakau survey and a guided walk. Here are some of the interesting things I saw.


This Porcelain Fiddler Crab (Uca annulipes) came with a bluish tint on its back. Not sure if it's due to the minerals in the environment, but even the other species of fiddlers we found here have a somewhat bluish carapace.


I found this Heart Cockle (Corculum cardissa) and several other groups found a few too. Appeared that they were in season. Could it be because Valentine's Day is just round the corner? Haha. Just kidding :P

This cockle is over-collected in some places and made into shellcraft. Certainly do not wish to see that happening in Singapore.


There appeared to be a lot more Hell's Fire Sea Anemones (Actinodendron sp.) compared to last time. This sea anemone gives really painful stings.


The Haddon's Carpet Anemone (Stichodactyla haddoni) has short and sticky tentacles which it uses to sting and trap its prey. The tentacles then work like a conveyor belt to bring the prey to the mouth in the middle.


On almost every trip to Semakau, we could see Noble Volutes (Cymbiola nobilis) laying eggs!


This longish animal is not a worm but a Synaptid Sea Cucumber (Family Synaptidae).


There were so many Knobbly Sea Stars (Protoreaster nodosus) that I lost count of how many I saw. Will have to look though the survey data sheet to get a feel of the numbers. Some groups saw more than 20 of them in their zone, while others did not see any at all. We only covered about half of the main intertidal area, and my guess was there were probably a few hundred of them at Semakau.


Ying Wei's group found the Pentaceraster mammilatus that July found in January.


There were lots of Upside-down Jellyfish (Cassiopea sp.), and some of them were almost as big as a dining plate!


We also saw many fat Funeral Nudibranchs (Jorunna funebris), and here's one of them.


Many of the volunteers were really excited to see Bigfin Reef Squids (Sepioteuthis sp.).


As I was helping with the survey, I found this pretty Spider Conch (Lambis lambis), which got its common name from its long spines resembling spider legs.


There was also a small Mosaic Crab (Lophozozymus pictor) - the most poisonous crab in Singapore.


Coelocarteria singaporensis, a sponge named after Singapore! This sponge is very common on Semakau.


There were several small Dragonfish Sea Cucumbers (Stichpus horrens). I wonder if we just missed the breeding season.

During the guided walk on Sunday, I was doing the coordination work and thus only took a few photos.


Among the few photos I took was this one which showed an Anemone Shrimp (Periclimenes brevicarpalis).


This neon green neon green Sunflower Mushroom Coral (Heliofungia actiniformis) appeared to be in rather bad shape.


It was infested with Acoel Worms (Family Acoela), which are believed to feed on copepods or secretions from corals or other sessile animals. While I have read that they seldom cause the host any harm, I really wonder if that's true, since this mushroom coral certainly look a lot more miserable than how it looked before it had these Acoel Worms.


We found a number of nudibranchs, including this Black Phyllid Nudibranch (Phyllidiella nigra). This nudibranch was said to be able to secrete very toxic chemicals into the surrounding water when it's stressed.


I also found this huge Ocellated Sea Cucumber (Stichopus ocellatus). If you look closely, you may see this Reg Egg Crab (Atergatis integerrimus) on the left side of this photo. I caught it initially, but got a little careless and it escaped! Fortunately, a few other groups still managed to spot it later.

All in all, it was a very busy but fun weekend!