メダカ産卵の時間的経過と要因

概要

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In Oryzias latipes, mating behaviour consists of several components. First, the male approaches the female, and embraces her body with the dorsal and anal fins. The two fishes come into close contact with each other side by side, each bending its body in an S-shape, and vibrate their bodies spasmodically. Eventually the male bumps its abdomen against that of the female once or twice when sperm are discharged. Two or three seconds after ejaculation, oviposition occurs. 1) The whole mating behaviour, from the beginning of the contact of male and female to the time of oviposition, takes 18.5±3.2 sec. on an average, the interval between the ejaculation and the ovulation being 2.53±0.72 sec. 2) When fishes are disturbed during the embrace, they separate but soon resume the same position. By this means, the whole period of embrace may be prolonged, but the interval between the last contact and the oviposition is longer than normal being about the same length as that between the beginning of contact and oviposition in undisturbed matings. 3) Under natural conditions, the ovulation usually takes place not later than 1-2 a.m. and oviposition at 4-6 a.m. However, if an appropriate light condition is maintained, the oviposition may follow the ovulation at any time of the days.
社団法人日本動物学会の論文
1964-01-15