Protein digestion in the phylum Mollusca

Little information is available on the subject of proteases in the phylum Mollusca. With the data that is present in this field, some correlation can be made concerning diet, habitat and the type or amount of proteases present in the animal. The small number of reports on the Classes Aplacophora and Monoplacophora is due to the fact that these animals are very difficult to obtain for they are deep-sea bottom dwellers. Some information is available on the Class Polyplacophora. These molluscs were shown to have extracellular proteases. It was speculated that this was due to the need for rapid digestion because of the chiton's littoral habitat. The Gastropoda and Pelecypoda range in diet from strict herbivores to strict carnivores. These animals do some foraging for their food. The carnivorous species of these groups have an increased number of proteases and a more efficient protein digestive process as compared to the three previously mentioned classes of molluscs. Wandering phagocytes and digestive gland cell fragments aid in the digestive process. The most advanced class of mollusc. Cephalopoda, is highly mobile and active. They are carnivorous and range some distance in search for food. Thus it is not surprising to find an Increased amount of proteases with a specialized and efficient digestive tract In cephalopods. The midgut gland is divided into two parts each secreting its own proteases. In contrast to the other classes of molluscs, the glands In the cephalopods are able to remain Inactive when a meal Is not present. The amount of Information concerning protein digestion in molluscs is small when one considers the size and complexity of this phylum. With the newer and better research techniques, additional studies on protein digestion in the molluscan species is pertinent. More Information is required before a clear understanding of protein digestion in molluscs is possible.Biology and Biochemistry, Department o