Anatomy and physiology of digestive tract of Crustaceans Decapods reared in aquaculture

— The digestive tract of crustacea is complex. It is composed of a short oesophagum, a stomach with two bags, and internal wall with appendags specialized in grinding of feeds. These hard mastication pieces represent the gastric mill. Setae,. filters included in the stomach structure allow the separation between food particles and liquid compounds. Those one are coming over through filters and more on to the digestive gland tubules or mid gut gland. In this organ, several types of cells play specialized functions : absorption, enzymes secretion, stocking function. Some cells of a new type, with undefined function, may be neurosecretions function, have been described recently. The end of tubules of digestive gland exhibits cells with embryonic characteristics. Digestive enzymes of crustacea are diversified : proteases, among which trypsin is the major one, carboxypeptidase, aminopeptidases and a protease of low molecular weight, II 000, recently thoroughly examined. Enzymes related to lipid metabolism are lipases and esterases. Amylases, maltases, chitinases are well represented. Enzyme secretions vary according to factors of external environment. Digestive enzymatic activities are under control of hormones which are about to be che, t t more in detail.