KOBAYASHI, SATOSHI and SHUHEI MATSUURA (Department of Fisheries, Faculty of Agriculture, Kyushu University). 1992. Ecological Studies on the Japanese Mitten Crab Eriocheir japonicus DE HAAN -III. Relative Growth of the Chela and Soft-hair Distribution on the Chela. Benthos Research, 45 : 1-9.
The relative growth pattern of the chela and the soft-hair distribution on the chela of the Japanese mitten crab, Eriocheir japonicus were investigated. According to the distribution pattern of dots plotted between the chela propodus height (CPH) and carapace width (CW), we distinguished three growth phases for the male and two phases for the female, and we fitted a regression line to each phase. The first and the second phases were distinguishable by an inflection at about 30 mm≤CW≤40 mm in both sexes, and the third phase in the male could be noted by a discontinuity from the second phase between 50 mm≤CW≤65 mm. The slope and/or Y-intercept of the regression line for each phase of the male was significantly higher than that for the same phase of the female. The area occupied by soft hair on the chela increased with the CW in both sexes, with the increase being greater in the male than in the female. In the large male (60 mm≤CW), the surface of the chela was almost wholly covered with hair, whereas in the large female, both the outer and inner lateral sides were partially covered.