FUNCTIONAL-MORPHOLOGY OF MOUTHPARTS AND FOREGUT OF THE LAST ZOEA, GLAUCOTHOE AND FIRST JUVENILE OF THE KING CRABS PARALITHODES-CAMTSCHATICUS, PARALITHODES-BREVIPES AND PARALITHODES-PLATYPUS

The feeding apparatus of the Paralithodes camtschaticus, P. brevipes a nd P. platypus during the transition zoea, glaucothoe and first juveni le stages were analyzed. The mandibles of zoeal larvae are well adapte d for grinding of food. The mandibles of the glaucothoe are uncalcifie d and rudimentary, and the mandibular lateral lobes are apparently inc apable of giving support to the masticatory movement. The setae of end opods and endites of the maxillae and endopods of the first and second maxillipeds are substituted for minute setae or denticles. The third maxilliped appear to be apparently developed, but the crista dentata o n the ischium is still not formed. The first juvenile has well calcifi ed mandible. The crista dentata on the third maxilliped is completely formed. The setose zoeal foregut has two chambers distinctively separa ted by a heavily setose cardiopyloric valve. The pyloric stomach has a well developed filter press. The glaucothoe has the foregut chambers and the cardiac pyloric valve unarmed or with few small setae present. The gastric mill and lateral teeth appear for the first time in the j uvenile foregut. These observations indicate changing in the feeding o f lithodids, in which they abstain from feeding during the glaucothoe stage.