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KMID : 0894520060100020135
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Development & Reproduction
2006 Volume.10 No. 2 p.135 ~ p.140
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Embryogenesis in the Octopus minor
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Kim Dong-Soo
Kim Jae-Man
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Abstract
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The small octopus(Octopus minor), a species in the cephalopod class spawns the fewer eggs compared with its relatives such as Octopus vulgaris and Octopus ocellatus and exerts special efforts in nursing eggs hiding in the deep cave beneath the mud flat. Correspondingly, its embryogenic process had been hardly observed. In this study, we induced the small octopus to spawn its eggs in the artificial spawning tube and to nurse the developing embryos under the periodical observation. The early embryogenic change in the fertilized eggs was appearance of blastodisc on the animal pole at 4 days after spawning. A mass of rudiments of several organs developed in the middle of the yolk sac at 28-th day and it moved gradually toward the animal pole. At 38 days after spawning, two eyes appeared on the head and the trunk with heart developed on the apical part of the yolk sac. At 45-th day of embryonic development, the trunk and head occupied a half of the egg capsule and consequently the yolk sac was reduced to a half of its original size. Two eyes became prominent at the bottom of the trunk with several spots at day 60. Embryonic development was completed at about 80 days after spawning and the arms stuffed the lower half of egg capsule. The young fry squeezed out of the egg capsules with their long and slender arms first and mantles later. Soon after hatching, it swam actively and squirted ink.
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KEYWORD
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Octopus minor, Embryogenesis, Artificial culture
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