NATURAL DIET AND FEEDING-HABITS OF THALAMITA-CRENATA (DECAPODA, PORTUNIDAE)

Thalamita crenata is one of the most common swimming crabs of the mang rove creeks of the East African coast. In Mida Creek, Kenya, this spec ies inhabits the extreme seaward fringe of the mangrove swamp and the intertidal platform in front of the mangal, sheltering in small pools during low tide. Gut content analysis reveals that T. crenata is a gen eralistic predator, its diet being mainly composed of bivalves and slo w-moving crustaceans. Both the stomach fullness and the relative prese nce of animal prey in the contents were significantly higher in crabs collected at sunset than in those caught at dawn. Stomach fullness see ms to depend also on the tidal rhythm; in fact it is higher during spr ing tide periods. Females had stomachs slightly fuller than those of m ales, while there was no difference in diet between juveniles and olde r specimens. Thalamita crenata forages more actively during daytime, t hus differing from the majority of swimming crabs. Both the great abun dance of this species and its diet, based on a wide range of slow-movi ng or sessile species, testify to the importance of the role played by this predator in the mangrove ecosystem of Mida Creek.