Fragile File Clam, Limaria fragilis
The Fragile File Clam, Limaria fragilis, is a species of bivalve mollusk belonging to the family Limidae. It’s found in shallow waters in the Indian and Pacific Oceans and is able to swim.
This clam has a pair of hinged, thin, asymmetric white valves and a red mantle with a fringe of long and tapering pink and grey banded tentacles at its edge. Also around the margin of the mantle is a row of tiny eyespots that can detect light and shade, and might alert the animal of an approaching predator.
It is widely distributed in the Indo-Pacific region. Its range includes the Philippines, the Marshall Islands, the Cook Islands, the Chagos Archipelago, Western Australia, Madagascar and the Red Sea. It often conceals itself in crevices or under stones with just the tentacles protruding.
This clam is a portentous hermaphrodite. The juveniles begin life as males and change sex to females as they grow. They have the ability to emit flashes of biolumiscent light, though why they do this is not clear.
They can swim slowly and continuously for about five minutes at one time. This happens by opening and closing its valves and expelling water in a stream from either side of the hinge, a type of jet propulsion.