Structural changes in the hepatopancreas of the rock lobster,Jasus edwardsii (Crustacea: Palinuridae) during development from the puerulus to post-puerulus

There is evidence for non-feeding in pueruli of palinurid lobsters during their long-distance swim to the coast and the succeeding post-settlement phase until they molt to the juveniles. For a better understanding of the nutritional supply during the puerulus stage, structural changes in the hepatopancreas were studied in post-settlement pueruli and first-molt, postpueruli of the rock lobster, Jasus edwardsii, collected on the southeast coast of the North Island, New Zealand between 1989 and 1990. In newly settled (transparent) pueruli, the epithelium of the hepatopancreas is dominated by presumed young R-(resorptive) cells, which are devoid of lipid droplets, but show active uptake of material from the hemolymph through pinocytosis at the basal region. In the fully pigmented puerulus, the hepatopancreas is dominated by R-cells containing massive lipid droplets; also present are small numbers of F-(fibrillar) and B-(blister-like) cells. This increase of lipid inclusion in the R-cells corresponds to the reduction in size of the fat bodies as the lobster develops from the transparent to the pigmented puerulus. After the molt to the post-puerulus, the R-cells are compressed, and the lipid droplets almost disappear, while the B-cells increase both in size and number. A mechanism is proposed in the present paper to explain energy storage and utilization during the puerulus and post-puerulus stages, wherein the fat bodies and the lipid inclusions play a vital role.