Piscivory of the Japanese giant box jellyfish <i>Morbakka virulenta</i>

Abstract

In this study, we investigated the trophic interactions between the Japanese giant box jellyfish, Morbakka virulenta, and fish in the central part of the Seto Inland Sea, western Japan, in autumn and winter. Occurring in the surface waters at nighttime, these cubomedusae, regardless of their size (1.5 to 22.5 cm in bell height), were found to be piscivorous, feeding mainly on the Japanese anchovy, as shown by their stomach contents analysis. This finding was supported by a stable isotopic analysis and by an unchanged cnidome, irrespective of the bell height of medusae. Their nocturnal occurrence near the surface often took place around the slack tide, during which the medusae were foraging with tentacles fully extended. Other associations between the medusae and fish were also observed at this time: presumed commensalism with juvenile Japanese horse mackerel, and predation by black scraper.

Development of <i>Carybdea brevipedalia</i> Kishinouye, 1891 (Cnidaria: Cubozoa: Carybdeida: Carybdeidae) collected from northern Japan

“…Envenomations by cubozoans are well known as they can pose a serious threat to public health (Williamson et al 1996). Several studies have been undertaken to investigate and understand the organisms including taxonomy (Gershwin 2005, 2006a, Bentlage and Lewis 2012, ecology (Lewis et al 2008, Chiaverano et al 2013, Kondo et al 2018, envenomation (Williamson et al 1980, 1996, Carrette and Sey-mour 2013, venom function and composition (Nagai et al 2000, Nagai 2003, Underwood and Seymour 2007, Brinkman and Burnell 2009 and nematocysts (Yanagihara et al 2002, Gershwin 2006b. At present, about 50 described cubozoan species are recognized, however, parts of the life cycle of only ten species are properly understood (Okada 1927, Werner et al 1971, Studebaker 1972, Arneson and Cutress 1976, Yamaguchi and Hartwick 1980, Hartwick 1991, Toshino et al 2013, Straehler-Pohl and Jarms 2011, Courtney et al 2016, Toshino et al 2016.…”