キンチャクダイの卵発生と仔魚期
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概要
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Chaetodontoplus septentrionalis (TEMMINCK et SCHLEGEL) is a common chaetodontid fish, distributed from the middle to southern Japan, Formosa and China. The spawning season seems to extend from July to early September in the western part of Yamaguchi Prefecture. On August 12 and 25, 1959 the authors carried out the artificial insemination of this fish and observed the egg development and hatched larvae at Tsunoshima, Hohoku Cho, Yamaguchi Prefecture. The egg is colorless and buoyant, spherical in shape measuring 0.82-0.88mm in diameter with a single oil globule measuring 0.15-0.20mm. The yolk is roughly segmented near its animal pole. Hatching took place in 16 hours at the water temperature of 26.8-28.0°C and in 22 hours and 40 minutes at 24-26°C. Newly hatched larvae (including the one of Fig. 1, i) were 1.9-2.0mm in total length, with the oil globule situated at the posterior part of the elongated oval-shaped yolk sac. The myotome number was 12+15=27 (vertebral number of this fish being 10+14=24). The melanophores were scattered all over the body excepting the end part of the tail and on the surface of the oil globule. The larvae were free from the xanthophores. In 22 hours, the eyes became slightly pigmented. The xantophores appeared on the oil globule and on the yolk around it, none on the body. The melanophores on the oil globule shifted to the anterior part of the yolk. The number of myotomes was 10+15=25. In 48 hours, the yolk and oil globule were almost consumed and the larva attained 2.6mm in total length. The mouth was formed, and pectoral fins well developed. The melanophores became larger and covered the body excepting the tail end. In 68 hours, the yolk were entirely consumed and the larva died.
- 公益社団法人 日本水産学会の論文