CHANGES WITH GROWTH IN FEEDING-HABITS AND GRAVEL TURNING BEHAVIOR OF THE WRASSE, CORIS-GAIMARD

Ontogenetic changes in the diet and foraging behavior of the wrasse, C oris gaimard, were studied on shallow reefs at Kuchierabu-jima Island, southern Japan. C. gaimard selected larger prey with growth, smaller individuals feeding on small crustaceans (e.g., gammarideans) and larg er ones feeding on larger molluscs (i.e., pelecypods, gastropods and c hitrons) and crabs. Although C. gaimard usually took prey from the sur face of the substrate, individuals of 5 cm TL and over also foraged fo r prey under gravel by turning over the latter. The relative frequency of gravel turning and size of gravel turned over increased with growt h, larger fish being able to take correspondingly larger prey (e.g., m olluscs and crabs) hiding under larger gravel. Especially for small in dividuals, foraging for alternative prey by turning over gravel may re duce the need to extend the foraging range and consequently the risk o f predation.