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Giant Clam

These giant clams are called giant for a reason — they can grow up to 1.5 meters (almost 5 feet) long! A bivalve mollusk is a soft-bodied invertebrate protected by a hard, two-part shell, and the giant clam is the biggest of the bunch!

 

These massive mollusks can be found in tropical waters throughout the Indo-Pacific Ocean, and in the south China seas as well as off the northern coast of Australia. They live in coral habitats, no more than 20 meters (65.6 feet) below the water’s surface. Just like fish, these creatures breathe through their gills, which they also use to filter food out of the surrounding water. However, this isn’t their main method of eating. Giant clams obtain most of their nutrients from the single-celled photosymbiotic algae living in their tissues. Without these algae, the giant clam will die.  

Aside from their astonishing size, these clams can be identified by the iridescent spots on their shells which can be green, purple, or blue. Their shell may even have some clear spots, referred to as “windows,” which may help the algae they live with receive more light.

 

 

Giant clams are prized both for their shell and as food, which has led the species to struggle and populations to decline. For decades they have been overfished due to intense, unregulated harvesting. Because of this threat, the IUCN has listed the giant clam as critically endangered.

 

 

Bivalves like the giant clam are essential for many marine ecosystems — partially due to their water-filtering properties.  

Keeping our oceans healthy means keeping creatures like the giant clam safe from overfishing. Learn more about Oceana’s campaign to promote responsible fishing.  

 

 

 

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