Abstract
The morphological characteristics of the exoskeleton in the abult and juvenile stages of the female Japanese mitten crab, Eriocheir japonicus were recorded with reference to the shape of the abdomen, the exposure of the edges of the thoracic sternums, and the growth of hairs in the margin of the abdomen, 1st〜4th thoracic sternums, and abdominal appendages. External changes which take place during molting were also examined. During the juvenile stage (carapace measuring less than 70 mm in width), the abdomen was found to grow relatively larger, both in length and in width gradually, during pre-puberty molting. However, when the crabs were reaching the abult stage (carapace greater than 35 mm in width), the abdomen was found to drastically grow larger during puberty molting, until it nearly covered the thoracic sternums.
