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rocky shore

Oyster Family Ostreidae Large oysters are fairly common on the rocky shore of Chek Jawa, although many have been poached. Small ones are also found among the barnacles. Stuck to a rock: Oysters have a two-part shell. In true oysters of the Family Ostreidae, the left valve is glued firmly to a hard surface. What we see is usually only the right valve. A layer of barnacles and algae often eventually develops over the right valve to camouflage them. It is hard to distinguish oyster species by their shells alone as their shells can take different shapes depending on the conditions they live in. Oyster Food: Like most other bivalves, oysters are filter feeders. At high tide, they open their shells a little. A current of water is generated through their shell and they sieve out the food particles with their enlarged gills. When the tide goes out, they clamp up their thick shells tightly with a strong muscle. Poky Oyster! The Spiked rock oyster (Saccostrea cuccullata) develops long, hollow spikes on its shell. This is probably a defence against predatory snails like Drills. The spines might make it difficult for such a snail to apply its acid-producing organ against the shell. Human uses: Oysters are relished by people everywhere as a delicacy. However, oysters may be affected by red tide and other harmful algal blooms. Such oysters can then be harmful to eat. Valuable pearls are only produced by some species of oysters. While other oysters may produce pearls, these are often not pretty enough to be valuable.		Spiked rock oyster Saccostrea cuccullata Camouflaged oyster Poached?!

quick facts
2-10cm, common on the rocky shore.

Classification:
Class Bivalvia
Phylum Mollusca

See also ...
Molluscs in general
Bivalves in general

Links
Ostreidae on The Gladys Archerd Shell Collection at Washington State University Tri-Cities Natural History Museum website: brief fact sheet on Oysters with photos.
Pearls on the American Museum of Natural History site: with details on what are pearls, freshwater and marine pearls and pearls in human history.

Other references

Tan, Leo W. H. & Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore Science Centre, Singapore. 160 pp. online version
Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.
Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach. Division of Biology, School of Science, Nanyang Technological University & Department of Zoology, the National University of Singapore. 160 pp.

a companion website to the chek jawa guidebook website©ria tan 2003 www.wildsingapore.com

a companion website to the chek jawa guidebook
website©ria tan 2003 www.wildsingapore.com