Thursday, June 3, 2010

Inter Tidal walk @ Big Sister's Island on 30 May 2010

117th Discovery Posting

Personally, I have been to Big Sister's Island for less than the fingers on one hand. So it was a great chance to both visit and introduce other people to this small little island to the south of Singapore through a guided inter tidal trip.

If you would like to read more about Big Sister's Island, you may visit
I need to mention that this was also the first public guided trip on Big Sisters organised by RMBR and I was guiding a group of rather experienced participants as most of them have to been other shores with us.
To start off, the first 'discovery' is something which I really like, feather stars (picture below)!
As their name suggests, their arms are a little like feathers, handle with care as they may break easily. I have seen them in many different colours besides red. They include black, yellow, white, etc. They are also related to the sea stars being in the same echinoderm phylum.

As we moved towards the coral reefs, a participant spot this school of juvenile catfish, second 'discovery' (picture below).Like other fishes you may find in the sea, juvenile catfishes are often seen in a group or what we call as a school of fish. They do this as a predator will find it harder to pounce on a group for food than compared to an individual, this is otherwise known as safety in numbers. Interestingly, as the cattail grows bigger, their group gets smaller and they are usually found alone when they are adults. As they have poisonous spines, it is not advised to touch them. One reason, I guess, why they are called catfish is because of their whiskers, these are usually to help them find food in murky waters.

If in case you are wondering, a cat's whiskers help it to find its way and move around. A little similar to the function of the catfish's whiskers.

Now, it is to be noted that Big Sister's Island has one of the nicest looking coral reefs where one can come really close up into (picture below). And my group, coral reefs, did spent a certain amount of time admiring at it. As we moved on, we came across this leaf slug which our hunter seeker has found for us, third 'discovery' (picture below).The leaf slug is named so mainly because of its colour which resembles a leaf. I reckon another reason which it is named as such is because that it is able to retain the chloroplasts of the seaweed it eats. These chloroplasts which it manages to retain will continue to carry out photosynthesis inside the slug and provide it with extra nutrients. Cool, isn't it?

Just to sidetrack a bit, we had this little joke about if we could do the same, would we be green in colour as well...hahaha

Moving on, our hunter seekers also found us a flatworm, fourth 'discovery' (picture below). As their name suggest, flatworms are really flat. This can help them to squeeze or move into narrow and small spaces to find food and at the same time to hide from their predators. At the same time, being really flat means that their bodies are easily tore when handled, so please handle them with them or don't handle them at all. One really interesting thing about them is that flatworms are hermaphrodites. In really simple terms, this means that a flat worm is both a guy and gal. In specific terms, flatworms have both the male and female reproductive organs.

And the last organism I am going to feature is this bohol nudibranch, fifth 'discovery' (picture below).First off, they are sea slugs. They are called nudibranchs because they have naked gills. Notice the flowery like thing near the center of the picture? That's the gills for this nudibranch. They may look like easy prey, they are however not. They protect themselves in different ways like producing distasteful substances, toxins and even acids. It is important to take note that these protective methods vary from species to species. Some of them will advertise themselves to be 'not nice to eat' with their really colourful bodies while some, like this bohol nudibranch will try to camouflage themselves.

As we were still wondering around the shore to look for more things, dark clouds and strong winds came in quickly and threaten to drench us, so we had no choice but to end the walk prematurely and leave the shore quickly.
Luckily, it did not rain eventually and the visitors has some time to take a short picnic and relax on the island.
Before I sign off, I would like to say thanks to all Coral Reefs, my group for the day. I hope the 3 first timers enjoyed themselves as I did not really give much details about the things we've seen that day and of course not forgetting the rest of my group.

Last note:
As a result of the passing rain clouds, we caught sight of a really beautiful rainbow which I would blog about in the next post, so do come back soon to check that posting out. =D

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