Sisters Island Walk on 30 May 2010

We finally conducted our very first public intertidal walk on Big Sister Island! Compared to the other walks that we have conducted, we have much fewer participants for this walk - only 30! This is because the Big Sister Island is much smaller than the other islands that we have conducted intertidal walks so far, and hence we had a smaller group that is more manageable to minimise impact to the environment.


We started off at the rocky shore, and at the edge of the shore, we found several feather stars (Class Crinoidea). These animals use their feather-like tentacles to collect plankton to feed on.


There were a number of Leaf Slugs (Elysia ornata) too. These slugs feed on the sap of algae, and are able to retain the chloroplast in the sap for photosynthesis to provide them with additional nutrients.


We soon reached a nice fringing reef with lots of hard corals and other reef organisms.


A few Striped Ribbon Worms (Baseodiscus quinquelineatus) were stranded on the rocks.


I noticed a few partially bleach coral colonies, but the situation was certainly not as bad as what we saw at Semakau.


There were a few Fireband Murex (Chicoreus torrefactus) among the corals. According to sources I found from the Web, the bright orange colour comes from a layer of skin (called the periostracum) which covers the shell.


There was also an Adhesive Sea Anemone (Cryptodendrum adhaesivum). Unlike most other sea anemones, this one has very short tentacles which it uses to sting its prey.


When we reached the small sandy lagoon, we saw many Moon Snails (Polinices mammilla) moving around just below the sand.


When we reached the big lagoon, I found a White-spotted Reef Hermit Crab (Dardanus megistos)! This hermit crab is seldom spotted on our shores. It was very shy though, and refused to come out for a nice photo :P


In the big lagoon, we also found a few Spider Conches (Lambis lambis). They were really well-camouflaged and it was quite hard to spot them when they were in the right environment.


A few nudibranchs were also spotted, including this Bohol's Nudibranch (Discodoris boholiensis).

Towards the end of the walk, the sky turned dark rather suddenly, but it fortunately did not rain and the participants managed to have a little picnic before we board the boat.


The boat ride back was mostly a rather peaceful one, until we reached Marina South Pier. One of the smaller boat accidentally crashed into our boat, and the impact smashed one of the windows! Fortunately, no one was hurt in this accident.