Relationship between dietary preferences and digestive enzyme complement of the slipper lobster Thenus orientalis (Decapoda: Scyllaridae)

Digestive capabilities of the commercially important slipper lobster Thenus orientalis were determined by comparing the range and concentration of digestive enzymes produced with the preferred diet of this and other slipper lobster species. Thenus orientalis is a specialized predator of bivalve molluscs, which are located by probing and digging the substratum. The edible flesh is removed by wedging, a progressive prying the shell valves apart, using the Sharp keratinized pereiopod dactyls. The range and concentration of digestive enzymes produced reflects the carnivorous diet of T. orientalis. The proteases trypsin and chymotrypsin are produced in high concentrations, the former representing a considerable proportion (up to 13%) of digestive gland protein. Detection of alpha-amylase and alpha-glucosidase indicates that T. orientalis is capable of hydrolyzing glycogen, the major storage polysaccharide in bivalve adductor muscle. These features indicate a digestive capability specialized for the hydrolysis of flesh. Significant N-acetyl beta-D-glucosaminidase activity revealed an ability by T. orientalis to hydrolyze chito-oligosaccharides and suggested that it can digest chitin from crustacean exoskeletons that have been found in the diet of other scyllarids. Digestive fluid pH (5.9) is consistent with the acid pH optima of carbohydrases, verifying that they are well adapted for extracellular digestion.