The giant clam gets only one chance to find a nice home. Once it fastens itself to a spot on a reef, there it sits for the rest of its life.
Giant clams achieve their enormous proportions by consuming the sugars and proteins produced by the billions of algae that live in their tissues. In exchange, they offer the algae a safe home and regular access to sunlight for photosynthesis, basking by day below the water's surface with their fluted shells open and their multi-coloured mantles exposed. They also use a siphon to draw in water to filter and consume passing plankton.
Average life span in the wild: 100 years or more
Size: 4 ft (1.2 m)
Weight: More than 440 lbs (200 kg)
Did you know? No two giant clams have the same colouration.
Never miss a Nat Geo moment
Join our curious community and you'll have access to some great features!
Personalised content reflecting your interests on the site
Watch exclusive videos before anyone else
Favourite content that you like or want to check out later
Free SMS and Email reminders so you never miss a show
Get notified when content that interests you is published
Share your photos on Snap! that could appear on TV
Share your thoughts and opinions on various matters
Receive a monthly newsletter with loads of great content