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3 November 2021 Ovarian Development and Larval Release of the Hermit Crab Clibanarius eurysternus (Hilgendorf, 1879) (Decapoda: Anomura: Diogenidae) in Okinawa, Japan
Naoya Osaka, Shu Chihara, Chihiro Yamauchi, Hiroki Takekata, Akihiro Takemura
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Abstract

This study investigated ovarian development and larval release in the hermit crab Clibanarius eurysternus, which inhabits the upper intertidal zone on Okinawa, Japan. Adult females were collected monthly and had a high gonadosomatic index (GSI) from May to October. Oocytes at vitellogenic stages were observed from May to October. Some females had post-ovulatory follicles in the ovary and embryos on the abdomen (ovigerous females) in June and August, suggesting active ovarian development and larval release during these months (breeding season). When adult females were collected weekly according to the lunar cycle, a high GSI with oocytes at the tertiary yolk globule stage in the ovaries was maintained in all lunar phases. Since post-ovulated follicles were seen in ovaries collected around the last quarter and new moons, darkness at night is needed for spawning. Ovigerous females exposed to stepwise changes in hydrostatic pressure exhibited significantly higher synchrony between larval release and high pressure at night from the last quarter moon to the new moon, suggesting the importance of the tidal amplitude cycle in larval release under non-moonlight conditions. We concluded that the continuity of synchronous spawning and larval release of C. eurysternus are repeated under darkness and high tide at night during the breeding season.

© 2021 Zoological Society of Japan
Naoya Osaka, Shu Chihara, Chihiro Yamauchi, Hiroki Takekata, and Akihiro Takemura "Ovarian Development and Larval Release of the Hermit Crab Clibanarius eurysternus (Hilgendorf, 1879) (Decapoda: Anomura: Diogenidae) in Okinawa, Japan," Zoological Science 38(6), 558-564, (3 November 2021). https://doi.org/10.2108/zs210041
Received: 27 April 2021; Accepted: 26 August 2021; Published: 3 November 2021
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