Flat Tree Oyster
Isognomon alatus
To 9cm

Highly flattened. Irregularly shaped valves joined by a long straight hinge. The exterior has a
loose flakes and rough, concentric rings. It varies in colour from a pale brownish olive to a purplish black. The interior of the shell (nacre) is yellowish with a purple-brown stain. The shell is attached to the substrate by a byssus thread

Filter feeder, drawing water into its shell and passing it through its gills, extracting plankton and small organic particle
Found, usually in dense groups, on the roots of mangroves, especially the Red Mangrove (Rhizophora mangle), harbour pilings and on shallow rocky areas, down to depths of 15 metres (50 ft) or more. On coral reefs it occurs on rock ledges and exposed rocks in areas of high sedimentation, forming mats of hundreds of individual animals.

Life Cycle
Breeding takes place after heavy rain has lowered the salinity of the water. Most of the adult oysters in the area take part in a mass spawning event when they all liberate their gametes at the same time. Fertilisation takes place in the water column and the larvae are planktonic. When they have passed through several developmental stages they settle to the seabed, undergo metamorphosis and attach themselves with byssus threads as miniature adults
    Ecological Descriptors
Habitat Size (cm) Diet Behaviour Sex 
R, Man 9 Pla, Det Sh
Flat Tree Oyster