サワガニの相対成長と生殖腺の成熟

概要

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The patterns of relative growth and gonadal maturation in a freshwater crab Geothelphusa dehaani were studied in a natural population inhabiting the Taniyamagawa River, Fukuoka, Japan. The relative growth in secondary sexual characteristics (SSC) with respect to carapace width (CW) was categorized into three phases, juvenile, adolescent and adult. There were two discontinuities among the phases: primary, between juvenile and adolescent, and secondary, between adolescent and adult. We fitted a regression formula to each phase of allometric growth. In both sexes, the allometric growth of SSC was not constant, and the adolescent and adult phases were clearly distinguishable. In the female, SSC appear at the abdominal segment, and the slope of the allometric regression formula increases in adolescence, and decreases in adulthood. In the male, SSC appears on one of the chelae, and the slope of the formula increases in adolescence and more in adulthood. The puberty molt occurred at the secondary discontinuity, when CW was about 18mm in males and 19mm in females. These sizes correspond to the CW which was attained at functional sexual maturity, and this was confirmed by an abrupt increase in the maturity index (MI). Accordingly, it is suggested that the marked trend in relative growth of the exoskeleton is closely related to the onset of functional gonadal maturation.
公益社団法人日本水産学会の論文
1995-07-15