Functional Morphology of Mouthparts and Foregut of the Last Zoea, Glaucothoe and First Juvenile of the King Crabs Paralithodes camtschaticus, P. brevipes and P, platypus

The feeding apparatus of the Paralithodes camtschaticus, P. brevipes and P. platypus during the transition zoea, glaucothoe and first juvenile stages were analyzed.The mandibles of zoeal larvae are well adapted for grinding of food.The mandibles of the glaucothoe are uncalcified and rudimentary, and the mandibular lateral lobes are apparently incapable of giving support to the masticatory move ment.The setae of endopods and endites of the maxillae and endopods of the first and second maxil lipeds are substituted for minute setae or denticles.The third maxilliped appear to be apparently devel oped, but the crista dentata on the ischium is still not formed.The first juvenile has well calcified mandi ble.The crista dentata on the third maxilliped is completely formed.The setose zoeal foregut has two chambers distinctively separated 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 juvenile foregut.These observations indicate changing in the feeding of lithodids, in which they abstain from feeding during the glaucothoe stage.