Digestive enzyme profiles of forgut and their differential between sexes of blue swimming crab, portunus pelagicus at Gelang Patah

Abstract

Blue swimming crab, Portunus pelagicus consumed variety kind of food as their diet. The study shows that their dietary items are molluscs, crabs and seagrass, including unidentified items that semi-digested. They are categorized as cannibalism because they consumed other crabs where the parts of crab's appendages were found in their foregut. They are omnivore group, as they eat other animal, they also consumed plants. Amylase, protease, and trypsin were detected in all sample and stages, except lipase, indicate that P. pelagicus readily digest dietary protein and carbohydrate at all stages. The changes in enzyme activities between stages reflect the changes in natural diet and feeding abilities. High proteolytic activity reflects a diet high in protein as show by matured males (MA). Meanwhile, carbohydrase activity reflects a diet with starch or cellulose that consumed by all stages especially matured males (MA), females with ovarian stage two (S2) and immature males (IM). And the high lipase activity reflects a diet high in fat as shows by female with ovarian stage four (S4).