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The present study was conducted to examine the occurrence and distribution of early juvenile land hermit crabs of the genus Coenobita on a small beach on the Boso Peninsula, Japan as a basis for understanding the important habitats that land hermit crabs use during the sea-to-land transition. The survey sites were supratidal zones at six points with heterogeneous topography, and visual surveys for early juveniles were conducted from middle July to late October in 2015 and 2016. The number of empty gastropod shells in four quadrats along the intertidal zone at each point was also counted in the 2016 survey. The occurrence of early juveniles varied among survey points and was spatially stable for two successive years. The first appearance and abundance of early juveniles varied among survey years. Early juveniles were abundant at points with a gravel bottom throughout the intertidal zone, and empty gastropod shells were also abundant at these points. The abundance of early juveniles was highly correlated with the amount of empty gastropod shells. Thus, our surveys suggested the importance of the sediment types and abundance of empty gastropod shells in the intertidal zones for settlement and landing by land hermit crabs.

Coenobita purpureus The juveniles exhibit a whitish/creamy color (Fig, 9A���F, 10A���C). The shield has a pale brownish patch on the anterior lower part of each side wall in some juveniles with an SL of> 1.6 mm after two months of age (Fig. 10 B). The chelipeds and the second and third pereiopods are generally pale brown at the distal and proximal parts of each segment; they appear to have pale brownish rings at the boundaries between segments (Fig. 9 A���F, 10A, B). The carpi of the pereiopods generally have a pale greyish stripe on the middle part in juveniles with an SL of> 1.6 mm after two months of age (Fig. 9 E, F, 10A���C). The palm of the cheliped has a large pale brownish patch on the lower portion and the propodi and dactyli of the second and third pereiopods have pale brownish portions in some juveniles with an SL of> 1.7 mm after three months of age (Fig. 10 A���E)., Published as part of Hamasaki, Katsuyuki, Tsuru, Takuma, Sanda, Tetsuya, Fujikawa, Shunsuke, Dan, Shigeki & Kitada, Shuichi, 2017, Ontogenetic change of body color patterns in laboratory-raised juveniles of six terrestrial hermit crab species, pp. 521-545 in Zootaxa 4226 (4) on page 533, DOI: 10.11646/zootaxa.4226.4.5, http://zenodo.org/record/265135

2011年の夏季(7-8月)に, 和歌山県白浜町に所在する京都大学瀬戸臨海実験所“南浜”で2個体のムラサキオカヤドカリが, 夜間(20-21時頃)に波打ち際で幼生を放出する行動(pumpingは数回と少ない)を示したので, 本州初記録として報告する., In summer of 2011 (July and August) release of larva of Coenobita purpureus was observed at a coast of Shirahama, Wakayama Prefecure, Honshu, Japan for the first time at night (ca 20-21:00), showing only several times of pumping behavior in two individuals.

In summer of 2013, number of individuals of Coenobita purpureus that released larvae at a coast of Shirahama, Wakayama Prefecure, Honshu, Japan was counted daily during the period between July 29 and August 19. A small number of individuals (maximal 7 ind./night) carried out such a behavior almost all the night in this period., 2013年夏季(7月29日-8月19日)に和歌山県白浜町に所在する京都大学瀬戸臨海実験所"南浜"で, ムラサキオカヤドカリが夜間に波打ち際で幼生放出する個体数の経日変化を調査した．その結果, ほぼ毎日この行動が実行されたが, 最多でも1夜に7個体しかみられなかった．このことから当該区域での再生産は少なく, 放出された幼生は無効分散となると推察される．

In summer of 2013, number of individuals of Coenobita purpureus that released larvae at a coast of Shirahama, Wakayama Prefecure, Honshu, Japan was counted daily during the period between July 29 and August 19. A small number of individuals (maximal 7 ind./night) carried out such a behavior almost all the night in this period.

[Der Mechanismus der Lauterzeugung bei dem landlebenden Einsiedlerkrebs Coenobita purpureus Stimpson, 1858 wurde untersucht. Alle drei untersuchten Tiere brachten Laute ohne Gebrauch des sogenannten Stridulationsorgans hervor. An zwei Tieren, die veranlast wurden, eine Schneckenschale mit Beobachtungslochern anzunehmen, konnte festgestellt werden, das die Laute bei raschem Vor- und Zuruckbewegen des Pleons durch Reibung der Uropoden an der Innenseite der Schale hervorgebracht werden. Ein Laut setzt sich entsprechend den Bewegungen der Uropoden aus 1-20 kurzen Tonen zusammen. Der Abstand der Tone liegt dabei zwischen 0.16-0.25 Sekunden und die hochste Frequenz betragt 6-8 kHz. Da Mannchen und Weibchen gleichermasen befahigt sind, Laute zu erzeigen, wird fur unwahrscheinlich gehalten, das die Laute der Anlockung des anderen Geschlechts dienen., Der Mechanismus der Lauterzeugung bei dem landlebenden Einsiedlerkrebs Coenobita purpureus Stimpson, 1858 wurde untersucht. Alle drei untersuchten Tiere brachten Laute ohne Gebrauch des sogenannten Stridulationsorgans hervor. An zwei Tieren, die veranlast wurden, eine Schneckenschale mit Beobachtungslochern anzunehmen, konnte festgestellt werden, das die Laute bei raschem Vor- und Zuruckbewegen des Pleons durch Reibung der Uropoden an der Innenseite der Schale hervorgebracht werden. Ein Laut setzt sich entsprechend den Bewegungen der Uropoden aus 1-20 kurzen Tonen zusammen. Der Abstand der Tone liegt dabei zwischen 0.16-0.25 Sekunden und die hochste Frequenz betragt 6-8 kHz. Da Mannchen und Weibchen gleichermasen befahigt sind, Laute zu erzeigen, wird fur unwahrscheinlich gehalten, das die Laute der Anlockung des anderen Geschlechts dienen.]

In summer of 2011 (July and August) release of larva of Coenobita purpureus was observed at a coast of Shirahama, Wakayama Prefecure, Honshu, Japan for the first time at night (ca 20-21:00), showing only several times of pumping behavior in two individuals.