ワニギスの卵および仔・稚魚
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概要
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Champsodon snyderi FRANZ is a small trachinoid fish distributed in southern Japan, and often eaten by the piscivors such as lizard fishes. The spawning season around Kyushu seems to extend from October to February according to the occurrence of the eggs in the sea (Table 1), however, some postlarvae were also caught in August. The egg, previously reported by the author as I. C, No. 62), is pelagic, spherical in shape, measuring 1.09-1.19mm in diameter, containing a single oil globule measuring 0.17-0.21mm in diameter, and usually accompanying a smaller single oil globule, measuring 0.02-0.08mm in diameter, in early developmental stages. The egg membrane as well as the yolk has not conspicuous structure, and the perivitelline space is narrow. The hatching took place in about 6 days at the water temperature 16-18°C. During the course of the egg and larval development only the melanophores appear. A single spinous appendage appears at the upper posterior part of the operculum toward the late embryonic development, and it is as long as one ninth of total length at hatching. The number of myotomes of the hatched larva is 30-32. The larvae are easily identified by the following characteristics: presence of a pair of long appendage (seems to be post-temporal spine) located at the upper posterior part of the operculum, large jaw with many teeth, bony crest above head, rather long ventral fins located at slightly before the pectoral fins, fin-formula and the number of myotomes. Another egg belonging to the genus Champsodon is collected from southern Kyushu. This egg differs from C. snyderi in early occurrence of the melanophores on the embryonal body, lacking melanophore on the ventral marginal fin of the newly hatched larva and the number of myotomes being 28.
- 社団法人 日本水産学会の論文