Ocean’s Health

Simple anatomy of the giant clam. Source: Ellis, 2000

Giant clams are filter feeders. They feed by opening their valves to expose their mantle. Large volumes of water along with many other algae, micro-organisms and organic matter, would enter the giant clam and through their gills. Particles get removed and the filtered seawater is released into the surroundings through the excurrent siphon.

Giant clam spewing filtered seawater. Source: David Greedy, Getty Images News

This filter-feeding ability prevents eutrophication which is detrimental to the marine ecosystem. More than 50 percent of the algae would usually be ingested and filtered. Algae is thus quickly removed from the water, preventing the flourishing of algae. A huge impact on the water’s cleanliness does not require many giant clams.

In addition, the symbiotic relationship between giant clams and zooxanthellae not only benefits the giant clams and the zooxanthellae but also the ocean’s oxygen levels. Photosynthesis by land plants produce of the world’s oxygen but photosynthesis by algae and cyanobacteria contributes to the other. Hence, photosynthesis by zooxanthellae will help to replenish the oxygen, just like how the land plants do.