Saturday 15 June Giant clam (Tridacna gigas) Giant clam fact
file - Find out more - Print factsheet Giant clam description
This enormous shellfish is the largest species of bivalve
mollusc in the fossil record, and the heaviest of all the living
molluscs (4). Like all bivalve molluscs, the shell of the giant
clam (Tridacna gigas) consists of two valves, although in the
larger giant clams these cannot close completely (6). The shell
is extremely thick and lacks bony plates; when viewed from
above, each valve has four to five inward facing triangular
projections (6). The mantle of the giant clam is visible between
the two shells, and is a golden brown, yellow or green, although
there may be such an abundance of small blue-green circles that
the overwhelming impression is of a beautiful iridescent colour
(6) (7). A number of pale or clear spots on the mantle, known as
'windows', allow sunlight to filter in through the mantle (6).
The mantle of the giant clam is completely fused with the
exception of two holes (o