Complete and rapid regeneration of fragments from the upside-down jellyfish Cassiopea

Abstract

The upside-down jellyfish Cassiopea increasingly occurs in many (sub-) tropical coastal habitats such as mangrove forests, seagrass meadows, and coral reefs. Its mixotrophic lifestyle and ecophysiological plasticity as well as a high regenerative capacity may be reasons for its success. While the regeneration of umbrella tissue and body structures (i.e. rhopalia and oral arms) was already demonstrated, it remains unclear whether a fully functioning medusa can regenerate from only umbrella tissue. In this study, we thus investigated the regeneration of umbrella fragments over time. We conducted a laboratory experiment for which we used 18 Cassiopea medusae of three different size classes that were cut into two pieces each, one fragment with oral arms and one without. Over a total observation period of 5 weeks, we regularly monitored survival, pulsation behavior, growth and the regeneration pattern of fragments. Findings revealed that 100% of the fragments with oral arms and 88% of the fragments without oral arms survived. Pulsation behavior occurred in all fragments and lasted until the end of the experiment in 94% of all fragments. The umbrella area of fragments without oral arms showed a significantly higher decrease in the first two weeks compared to fragments with oral arms. A complete regeneration of umbrella tissue was observed in all fragments, with and without oral arms alike, and 50% of all fragments even regenerated rhopalia or oral arms as body structures after 33 days. These results suggest an outstanding regenerative capacity of Cassiopea jellyfish after fragmentation. This may contribute to (i) explain the currently observed success of upside-down jellyfish and (ii) extend our knowledge about its regeneration process, which might even act as an asexual reproduction mode in Cassiopea.

Banggai cardinalfish (Pterapogon kauderni) monitoring in Bokan Kepulauan (2017-2021) highlights the need for the “BCF Garden” approach

“…The Cassiopea lifecycle can involve both polyp and medusa forms, with the former capable of asexual reproduction through budding and the latter capable of sexual reproduction with male, female, and (more rarely) hermaphroditic individuals [56]. However, regeneration may also enable asexual reproduction in this phase [57].…”

Light exposure induces phenotypic plasticity of the upside-down jellyfishCassiopeaand its endosymbiotic dinoflagellates

“…Cassiopea spp. are highly plastic, resilient organisms that can survive extreme physical and environmental stress across a variety of environmental conditions (Anthony et al, 2023c; Banha et al, 2020; Ostendarp et al, 2022; Tilstra et al, 2022). However, the Cassiopea holobiont’s phenotypic (behavior, morphology, physiology) responses to the environment, and the relationships between response strategies, are poorly defined and understood.…”

Neuromuscular development in the emerging scyphozoan model system, Cassiopea xamachana: implications for the evolution of cnidarian nervous systems

“…Cassiopea xamachana has received some attention for research into the interaction with endosymbiotic microalgae, Symbiodiniaceae, which are hosted in polyps, planuloids, ephyrae, and medusae ( Hofmann et al, 1978 , 1996 ; Verde and McCloskey, 1998 ; Ohdera et al, 2018 ). Recently, other topics such as regeneration ( Gamero-Mora et al, 2019 ; Ostendarp et al, 2022 ; Mammone et al, 2023 ), the composition and function of the blue pigment present in the medusa ( Phelan et al, 2006 ), its stinging cassiosomes ( Ames et al, 2020 ), and neuromuscular anatomy, with focus on the medusa stage, were also targeted ( Passano, 2004 ; Santhanakrishnan et al, 2012 ). The present study focuses on the neuromuscular development from the planula larva through metamorphosis into the juvenile polyp.…”