Overnite at St John's

It's another low tide weekend, and we decided to go to St John's Island and spent a night at the Tropical Marine Science Institute.


Our first stop was the little patch of mangrove on the island.


There were lots of red berry snails (Sphaerassiminea miniata) on the muddy substrate.


And finally, we found what we were looking for - Api-api jambu (Avicennia marina), also commonly known as the grey mangrove or white mangrove. It is the rarest Avicennia species in Singapore, and this was only my second time seeing this plant locally.


Our next stop was the sandy shore, and we found lots of soldier crabs (Dotilla myctiroides) "marching" around on the sand.


And what's this lying on the sand? A seven-armed sand-sifting sea star (Archaster typicus)! My first time seeing one! Previously, I have only seen those with 4, 5 and 6 arms.


There was a Bryopsis agal bloom, and with the algae came its feeder - the leaf slug (Elysia ornata).


A spotted-tail frogfish (Lophiocharon trisignatus) was also found among the seagrass and seaweed.


St John's Island is one of those places which we can often find spider conches (Lambis lambis). These snails are very well-camouflaged, but once you turn it over, your can see its pretty coloration on its underside, the long trapdoor and the two cute little eyes.


When a spider conch dies, its shell is sometimes taken over by hermit crabs, such as this hairy hermit crab (probably Dardanus lagopodes), which we regularly spot on St John's.


As I was looking at the hermit crab, I suddenly noticed that a piece of dead coral nearby was moving. Picking it up, I saw this little crab inside. I have seen such crabs living in holes on dead coral pieces many times, but had not been able to found out what species they belong to.


This tiny little sap-sucking slug (Thuridilla gracilis), hardly more than 1cm long, was found by RH.


This blue-spotted fantail ray (Taeniura lymma) was not camera-shy at all, and hardly moved as we took our time to take photos of it.


There were lots of soft corals in the various tidal pools form during the low tide.


Corallimorphs were another common sight at St John's. Related to corals and anemones, they were sometimes also called mushroom anemones as they have a wide oral disc attached to the substrate by a thin stalk, making them looking like mushrooms.


Some how, there were far less hard corals these days at St John's Island, and we are not really sure why. Many died and the intertidal reef was replaced by coral rubble at most places along the rocky shore that we usually visit. The blue corals (Heliopora sp.) seemed to be doing well though. The above photos show a few mushroom corals (Fungia sp.) among the blue corals.


Can you spot the octopus above?


This pretty flatworm (Pseudobiceros bedfordi) was swimming near the water surface when I spotted it.


I also found this nudibranch, probably a Discodoris lilacina.


As the tide eventually gone higher, we headed back to dry land and found the sea poison tree (Barringtonia asiatica) blooming.


A few land hermit crabs (Coenobita sp.) were also out and about.


On the next morning when we were at the jetty to take the ferry back, we noticed that the tide was ultra high! Wonder if it will overflow onto the jetty after we left the island. Hmm...