アジアカブトエビの交尾行動と産卵数
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概要
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A study group comprising one virgin female and two male Asian tadpole shirimps were kept in an aquarium which simulated a typical rice paddy environment as closely as possible.The number of eggs laid by the female was counted every other day.The yield of eggs recovered from the fine sand in the aquarium was 98 percent or more.The female kept up to 113 eggs in her egg pouches,and oviposited up to 406 eggs in a day.Active oviposition began two weeks after hatching and continued for three weeks.The female laid up to 3,741 eggs during her lifetime,with an average of 3,190.The behavior of the three shrimps in the aquarium was recorded on video tape for 96 hours.While the female did not exhibit any contact behavior,each male adtivity exhibited contact behavior directed ot both the female and the other male.The male seemed not to rocognize that he was acting on a female until his copulation behavior was accepted.Females engaged in copulation 89 times a day and oviposition 32.5 times a day.アジアカブトエビの処女雌1個体と雄2個体を，可能な限り自然の水田と同じ環境を保った水槽で飼育・産卵させ，その卵数を2日毎に数えた。水田の土壤に変えて卵の径よりも細かい粒度の砂を水槽内にいれる方法を考案したので，卵の回収率は98％以上の精度であった。雌は貯卵嚢に最大113個の成熟卵を保有し，1日に最大406個の卵を産んでいた。活発な産卵が行われるのは，孵化2週間後からの3週間程度で，一生の間に雌は最大では3741個の，平均でも3190個の卵を産んでいた。水槽内の3個体の行動を延べ96時間にわたって，ビデオカメラで記録した。雌は接触行動を起こすことはないが，雄は活発に，しかも，相手かまわず雌雄に対して行う。相手が交尾対象である雌と認識するのは，雄の交尾行動を雌が受け入れた時であるらしい。雌は1日に89回の交尾を受け入れ，32．5回の産卵行動をしていたことがビデオに記録されていた。