Thursday, May 15, 2008

Semakau Inter-Tidal Walk on 10 May 2008

Fifty Eighth Discovery Posting:

A very late posting for a walk last Saturday due to many other outings to places like Bukit Timah, Pulau Ubin and Sungei Buloh, hopefully I will find the energy to sit down to blog about some of those trips.

Anyway, for this posting, I would like to blog about two organisms which I seldom blog about and you can find at inter-tidal zones.

First and second 'discovery' are the same (pictures below). Do you think they are plants or animals?

Discovery Note:
1. They are animals called the fan worm or featherduster worm.
2. They are segmented worms.
3. They feed on the tiny particles found in the water.
4. Fan worms live in a flexible and leathery tube which they hide into when they sense danger or they are exposed to the air.
5. Read more about the fan worm on the online Chek Jawa guide.

Third 'discovery' is a giant clam (picture below)
Discovery Note:
1. They are the largest living bivalve mollusc and also known as the bear's paw clam
2. They can weigh more than 227 kilograms and measure as much as 1.2 metres across, and have an average lifespan in the wild of 100 years or more.
3. An interesting symbiosis occurs between a unicellular green alga (Zooanthella ) and the clam. The algae live in the tissues of the clam's siphon and mantle; they are able to obtain the sunlight needed for photosynthesis because the clam lies with its valves opening upward and part of the thick, purple mantle extruding over the shell.
4. In addition, there are crystalloid vesicles on the mantle surface that let in sunlight, thus allowing the algae to live deep within the tissues. The clam uses the algae as a supplementary or perhaps even a major source of food.

It was another great outing as we stayed overnight on the island before the morning inter-tidal walk, and an overnight stay means that we got a chance to see the fireflies! Although it was impossible for me to take a photo of them, it was rewarding enough just to look at them flying around amongst the trees. =)

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