Clams

Giant clams are among the most distinctive animals on the Great Barrier Reef.

Tridacna - one of the giant clams on the Great Barrier Reef

Feeding

Giant clams are filter-feeders which draw water into their bodies and filter out food using special gills. Like corals, giant clams have symbiotic algae (zooxanthellae) that supply extra nutrients.

Defence

Giant clams rely on their thick shells and the ability to close up (hence the expression 'to clam up') for protection against predators.

Reproduction

Giant clams are hermaphrodites and reproduce by releasing eggs and sperm into the water column where they combine to form a planktonic larval stage. Mass spawnings are triggered by other individuals spawning.

Threats

Giant clams are particularly vulnerable to harassment by divers and snorkellers.

Giant clams have been heavily harvested legally and illegally throughout the Pacific and on the Great Barrier Reef for food. Clam farming operations are now being established to raise clams to reduce the impact on natural populations.

To minimise stress on these animals, divers and snorkellers should look at clams and not touch them.