Creature Feature #106: Clam

The Giant Clam is the largest living Bivalve mollusc and can measure up to 120 cm across. Long-lived, it has an average lifespan of over 100 years and can be found at depths of 20m, on a substrate of broken coral and shells. Giant Clams are hermaphrodites and can self-fertilise, but they also engage in broadcast spawning - synchronising with neighbouring clams - releasing eggs and sperm into the water. When the eggs are fertilised, they free float for about 12 hours before hatching into a free-swimming larvae. This trocophore quickly begins to produce a calcite shell and develops a "foot" which it uses to traverse the sea bed, although it can still swim at this point. After the first week it begins to slow down its movement as it seeks an appropriate location to become sessile. Once settled it adapts into the sedentary adult form.