30 March 2015

Ocean Giants: Giant Clam



You don't have to look too deep in the ocean for exotic beauty because the vast coral reefs already offer some of the most spectacular underwater sights. Coral reefs, the marine counterpart of rainforests, serve as habitat to various species ranging from invertebrates such as mollusks to mammals such as sea turtles. And among the species of mollusks is the largest known bivalve, the giant clam Tridacna gigas. It is found in the Indo-West Pacific, from the intertidal zone to depths of 35 m (Bernard et al 1993) [1]. The largest known individual measured 137 cm in length and weighed 250 kg [2]. 

Giant clam on reef, photo from www.arkive.org

Giant clams are known for their unique ability to ‘self-feed’. How do they do it? During an early stage in their life cycle, they ingest dinoflagellate algae. The algae are not digested but rather propagate in the gut. Basically, the clam is dependent on this algae and filters sea water for it to grow at such length. Giant clam meat, i.e., from its adductor muscle, is in high demand. Unregulated harvesting of wild stocks posed and continues to threaten native populations throughout the Indo-Pacific. This led to attempts to develop harvestable cultured populations [3]. Because of this, information on the biology and ecology of giant clams were rendered available in the scientific literature. You may visit SeaLifeBase to view this information.

Giant clams in spawning tank in mariculture plant, photo from www.arkive.org

If you have other information on them, which you wish to include in our information system, please e-mail us at sealifebase@fin.ph or join us as a collaborator.

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[1] Bernard FR et al (1993) Catalogue of the Living Marine Bivalve Molluscs in China. Hong Kong University Press, 121 p.
[2] McClain, C.R., et al. 2015. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 2:e715. Accessed from https://peerj.com/articles/715/
[3] Munro JL (1993) Chapter 13: Giant clams. FFA Report 92/75.


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