Recent Trips to Semakau

Went to Semakau a few times recently, but never had the time to blog. Here are just a selection of the interesting things I have seen :)


One of the most surprising find over the past few trips must be this Giant Honeycomb Oyster (Hyotissa hyotis), which previously I have only seen while diving in the region! So I was really surprised to find it in the intertidal area. This particular individual was probably about 25 cm long - a lot bigger than even the Boring Giant Clam, and almost the same size as the Fluted Giant Clam. Apparently this oyster got its common name because of its shell structure, which is foam-like under magnification.


We also found this interesting clam which burrowed into a rock, and we are still not sure of its identity yet.


This Window Pane Shell (Placuna placenta) is not exactly something special, but thought I would highlight it since most of the time I blogged about another similar species, Placuna ephippium.


This sponge (Spongia sp.) may not appear special, but if you look carefully, you can actually see there's something bulging out at the top - that's an embedded Vulsella clam! This clam is said to live only in spongiid sponges!


We also saw many Tube Snails (Vermetus sp.) - something that somehow I never noticed before this trip on Semakau! Guess I must be rather blind before.


Yet another new thing we saw was this tiny sea hare on a red algae! It's less than 1 cm long. Have no idea what species this is as well.


This is also not something new, but thought I would highlight since these Funeral Nudibranchs (Jorunna funebris) appear to be in season, and we saw many pairs of them recently.


This Bigfin Reef Squid (Sepioteuthis lessoniana) was busy flashing its colours when we saw it.


Somehow we do not often see hydroids at Semakau, but recently, we saw quite a few different ones! The above was a rather pretty one that was pinkish in colour.


This whitish feathery hydroid supposedly stings quite badly.


Here's another hydroid I found. You can even see the polyps with the little tentacles!


And there is this encrusting hydroid (Family Tubulariidae) which can be super abundant at some parts of the shore.


Looking rather similar to the encrusting hydroid are these soft corals. You can see a reddish brown colony on the right, and a much smaller lighter orange colony on the left. We initially thought they were the same, until we noticed that the lighter coloured ones can retract its polyps, but not the darker coloured ones. I suspect the darker ones to be some Xenia sp. Not sure about the lighter ones though.


Here's the lighter coloured colony with all the polyps retracted.


Finally, I found a colony of Cladiella Soft Coral (Cladiella sp.)! For my past few trips, I have only been seeing the similar-looking Sinularia Soft Coral.


We also saw a few sea pens.


And finally, a nicely coloured Adhesive Sea Anemone (Cryptodendrum adhaesivum). For the past few times I saw them on Semakau, they were all rather bleached.


This was the first time that I managed to get a decent photo of this flatworm, Pseudoceros bifurcus, at Semakau.


Several solitary sea squirt, Polycarpa sp., were also seen.


I found this creeping legume on the rock bund, but have no idea what species it is.


The Fever Nut (Caesalpinia bonduc) was fruiting! There are only three naturally occuring Fever Nut in Singapore, and only one on mainland Singapore that was spotted by me at Punggol Beach. Unfortunately, that one was chopped down by some contractors. I informed NParks and they have taken measures to better protect the plant at Punggol by putting up some sticks for what's left of the plant. It was supposed to be rather hardy, so should be able to regrow well. NParks has also taken some cuttings of the plant to be grown in their nursery. I will also be passing them some of the seeds collected from Semakau. Would like to thank Mr Wong Tuan Wah, Geoffrey Davison, Shufen and other staff of the NParks conservation division for taking the necessary actions to better protect this critically endangered plant :)


The Api-api Ludat (Avicennia marina) was also fruiting! Semakau is the only place in Singapore which has a good population (I counted at least 15 last time) of this critically endangered mangrove plant.


I found a Sea Almond (Terminalia catappa) that was fruiting.


But more interestingly, was that the same tree was also flowering!


And there were also several Cotton Stainer Bugs (Dysdercus decussatus), happily mating. Good to see reproduction at work at Semakau!

Will be going to Semakau again next week for an intertidal walk and a survey. Hopefully will see more new stuff! :)