First report of a precocious form of strobilation in a jellyfish, the South American Pacific sea nettle Chrysaora plocam
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First report of a precocious form of strobilation in a jellyfish, the South American Pacific sea nettle Chrysaora plocamia Leonardo Campos 1 & Karina González 2,3 & Janja Ceh 2,4,5 Received: 12 May 2020 / Revised: 8 August 2020 / Accepted: 13 August 2020 # Senckenberg Gesellschaft für Naturforschung 2020
Abstract Scyphozoans display a high level of developmental plasticity, including asexual reproductive strategies in their polyps. Irrespective of the alternating medusa-polyp life cycle, life stages or even complete generations can be omitted, occasionally or consistently, in some species. For example, ephyrae can be produced directly by planulae, leaving out the polyp generation, and polyps can produce free-swimming planula-like propagules, thus bypassing the medusa generation. Here, we raised Chrysaora plocamia polyps under unusually high, naturally occurring temperatures, which resulted in these polyps being unable to strobilate but able to form podocysts. Early excysts that hatched from these podocysts produced ephyrae in a premature type of strobilation. This developmental shortcut, previously unknown in scyphozoan life cycles, is described in the present report. Keywords Scyphozoa . Jellyfish reproduction . Polyp . Ephyrae . Podocysts . Chile
Introduction The life cycle of scyphozoans (reviewed by Helm 2018) is generally characterized by alternating medusa- and polyp generations. Consequently, they have to progress through multiple body plan changes. The medusa generation is pelagic and reproduces sexually: a motile planula is produced, settles on a suitable substrate, metamorphoses, and grows into a sessile polyp, initiating the benthic phase. As opposed to the medusa generation, the polyp, when fully developed (scyphistoma), Communicated by B. W. Hoeksema * Janja Ceh [email protected] 1
Centro Regional de Investigación y Desarrollo Sustentable de Atacama, Universidad de Atacama, Copiapo, Chile
2
Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Recursos del Mar, Universidad de Antofagasta, Antofagasta, Chile
3
Núcleo Milenio INVASAL, Concepción, Chile
4
Laboratory of Microbial Complexity and Functional Ecology, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
5
Max Planck Tandem Group in Plant Microbial Ecology, Universidad del Valle, Calle 13 100-00, Building E20, 760032 Cali, Valle del Cauca, Colombia
reproduces asexually, producing medusae via a partial metamorphosis called strobilation. Environmental factors, such as changes in temperature, combined with endogenous rhythms of the animal and chemical cues (Spangenberg 1967; Loeb 1972, 1974; Hofmann et al. 1978; Dawson and Martin 2001; Daryanabard and Dawson 2008; Fuchs et al. 2014), induce the scyphistoma to undergo transverse constrictions, subdividing its body into segmental discs. These develop into ephyrae (Fig. 1a, b), which are liberated one by one and further develop into medusae, marking the beginning of the pelagic phase and closing the cycle when the medusa reaches sexu
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