水槽で飼育したガザミの脱皮と成長

概要

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To estimate the molting and growth of the swimming crab Portunus (Portunus) trituberculatus, juveniles (carapace width: 14-26mm) hatched in July and large crabs (carapace width: 166-233mm) caught by trawl net in Osaka Bay were reared in concrete tanks in the laboratory. Most of the juveniles reached the 10th or 11th instar in November, and their average cara-pace widths were 115mm for females and 108mm for males. In the year after hibernation they molted 2 or 3 times, reaching the 12th or 13th instar. Their average carapace widths in November were 183mm for females and 190mm for males. Trawl-caught crabs molted once a year for both sexes. Their molting periods are presumed to be August or September for females and about August for males. The relationship between the instar number and the average carapace width can be expressed by a logistic equation, and the relationship between pre-molt and post-molt carapace widths can be expressed by two straight lines with an inflex-ion in the 9-10th instar prior to maturation.