Wednesday, September 2, 2009

Guiding @ Semakau - 23 Aug 09


This sleepyhead woke up to the music of a heavy downpour in the middle of the night, and was torn between feeling excited about guiding, and upset about not being able to sleep in! I'm amazed that I managed to drag myself out of bed to make my way to Marina South (and yes, now I know walks will never be cancelled...).

I was pleased to be assigned to the Knobbly Sea Star group ('cause its one more badge for me!). Despite the lack of sleep, it was definitely an enjoyable trip with our 9 participants from Queensway Sec Sch.
Thankfully, the rain stopped when we reached the island. The tranquility of the secondary forest and the breathe-taking scenary of the intertidal area never fails to put one at ease.

The hunters-seekers, as usual, didnt fail us and showed us the interesting marine life of the island.

We were lucky with sea cucumbers that day and saw 4 out of the 5 sea cucumbers commonly seen at Semakau.


From top left (clockwise):

The Sandfish Sea Cucumber (Holothuria scabra) is the delicacy we find in our dishes, but only after its processed as its mildly poisonous.

My audience initially thought that the Synaptid Sea Cucumber (Family Synaptidae) is a worm when I ask them to make a guess. They were surprised to hear that this is the longest sea cucumber with very delicate walls, and has hooked spicules. It feeds on detritus by lashing its tentacles in the surrounding waters.

The Dragonfish Sea Cucumber (Stichopus horrens) gets very stressed up when its out of water for too long. It is known to 'melt' (!!), disintegrate if left to suntan, and may eventually die. In fact, just handling them for a few seconds may cause their disintegration, so all of us (including the participants) are always encouraged not to handle such delicate wildlife and leave them in their natural environment.

The hunters-seekers found this HUGE Oscellated Sea Cucumber (Stichopus ocellatus). To my best estimation, its almost 40cm long! Its papillae (eye rings) is believed to have sensory functions to help it move around. It appears as if thousands of eyes were staring right back at me - a little scary, I must say.

  

There was also a sumptuous display of Nudibranchs - a type of sea slug named after their exposed gills on the back of its body (in latin, Nudibranch means naked gills). Interestingly, these slugs are born with shells, but loses them as they become adults. They are carnivores, grazing on algae, sponges, corals, and some, even other nudibranchs.

Their two sensitive tentacles (called rhinophores) located on top of their heads, are their handy detector of preys. I read from the internet that they derive their color from the food they eat, and some even retain the foul-tasting poisons of their prey. Their bright colours and yucky tasting glands, in turn becomes its defense mechanisms against predators.

Here, we have (from top left, clockwise) the Black Margined Nudibranch (Glossodoris atromarginata); Black Phyllid Nudibranchs (Phyllidiella nigra); and Polka Dot Nudibranch (Jorunna funebris).

 

Flatworms, as the name suggest, is very flat and are the simplest of worms. They have no skeleton, no circulatory nor respiratory system, instead their flattened shapes allow oxygen and nutrients to pass through their bodies by diffusion.

The 2 we encountered on this trip was the Acanthozoon sp. and one that I can't quite identify...I ploughed through the internet and realises that while it resembles Pseudobiceros fulgor, the lines and colour are quite different.  
 

We were also treated to a galaxy of sea stars, including the juvenile Cushion Star (Culcita novaeguineae). It certainly didnt look any much larger since the last time I saw it a few weeks ago. Looking forward to seeing it grow into an adult, slowly, but surely!


The unidentified sea star, which made is first appearance on the launch of Project Semakau, made a guest appearance too! It has certainly grown in size since Nov 08. While it has knobs on its upperside, it looks rather different from the Knobbly Sea Star. My group members guessed that it must be a cross breed.. =)


Along with it, the unidentified sea star brought us his friend - a brittle star (Ophiuroidea) that was probably taking shelter on its underside. Like the lizard that drops its tail, a brittle star may drop off an arm when threatened. To make its escape, the brittle star's dropped arm may continue to wriggle to distract the predator.


The highlight of the trip has to be the appearances of the Knobbly Sea Star (Protoreaster nodosus). I used to think that all sea stars only have 5 arms, only to realised now, that its not true. The 6 arm Knobbly we saw is evidence that some sea stars have more than 5 arms! While they are brightly coloured and covered with knobs, Knobbly sea stars are not venomous.While they are mostly red in colour, some come in brown too. Don't the brown Knobbly Sea Star look like a piece of choc chip cookie?

We also saw a Knobbly Sea star that seemed to have lost an arm, and is in the process of regenerating it. Hopefully it will get well soon!


Some of my participants cringed when I shared about this beautiful mollusc. Indeed, while 人不可貌象, the Noble Volute (Cymbiola nobilis) can't be judged by its shell too. This mollusc may look pretty and harmless but its actually a fierce predator of other snails. It wraps its prey with its siphon in an attempt to suffocate the victim. When the prey has no choice but to open its shell to breathe, the Noble Volute quickly snap in to eat the prey.



The pole vaulter was also sighted - The Spider Conch (Lambis Lambis), named after its long spider-like spines, has a strong operculum that helps it to 'jump' around. Although it is very well camouflaged by a thick layer of algae, it has a really beautiful and smooth underside, 可算是内有乾坤!


We also saw the Hell's Fire Anemone (Actinodendron sp.), which I almost mistaken as the upside down jelly fish. This animal got its name from the painful stings it gives.

  

The resident Fluted Giant Clam (Tridacna squamosa) was patiently awaiting our arrival. Unlike most bivalves, the Giant Clam harbours symbiotic zooxanthellae which produces food through photosynthesis, for sharing. This also explains why the mantle is exposed to allow sufficient sunlight for the algae (else the clam may go hungry!) to make food.


On our way back, I found a Anemone Shrimp (Periclimenes brevicarpalis) amongst a Carpet Anemone. No matter how hard I look, I could only find one even though they often come in pairs. The Anemone Shrimp is able to live in harmony with its host, despite the Anemone's stings, by coating itself with a layer of mucus produced by the Anemone. This layer of mucus prevents it from being stung by the host.



The partcipants crossing the Seagrass meadow:
Presenting the Knobblies:

The participants embarked on the landfill tour after the intertidal walk. Unfortunately, none of us were able to help R(I would have loved to, but I have never been on one! =P heh..excuses...), and he had to guide despite a really bad throat. I'm sure the sacrifice is worthwhile, in exchange for an enjoyable experience for all the participants (I hope!).

I was absent from the track girls' weekly run and they chided me for not informing them about the trips to Semakau. Naturally, they were upset when told that there are no more guided walks this year. Next year ok? While I'm happy to share the wonders of this island, I would prefer not to have you girls in my group if I'm guiding!! =P

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