“Indirect development” increases reproductive plasticity and contributes to the success of scyphozoan jellyfish in the oceans

Abstract

Ecologists and evolutionary biologists have been looking for the key(s) to the success of scyphomedusae through their long evolutionary history in multiple habitats. Their ability to generate young medusae (ephyrae) via two distinct reproductive strategies, strobilation or direct development from planula into ephyra without a polyp stage, has been a potential explanation. In addition to these reproductive modes, here we provide evidence of a third ephyral production which has been rarely observed and often confused with direct development from planula into ephyra. Planulae of Aurelia relicta Scorrano et al. 2017 and Cotylorhiza tuberculata (Macri 1778) settled and formed fully-grown polyps which transformed into ephyrae within several days. In distinction to monodisk strobilation, the basal polyp of indirect development was merely a non-tentaculate stalk that dissolved shortly after detachment of the ephyra. We provide a fully detailed description of this variant that increases reproductive plasticity within scyphozoan life cycles and is different than either true direct development or the monodisk strobilation. Our observations of this pattern in co-occurrence with mono- and polydisk strobilation in Aurelia spp. suggest that this reproductive mode may be crucial for the survival of some scyphozoan populations within the frame of a bet-hedging strategy and contribute to their long evolutionary success throughout the varied conditions of past and future oceans.

Mucus secretions in Cnidarian, an ecological, adaptive and evolutive tool

“…Cnidarians present two forms, the polyp and the jellyfish, sessile and planktonic respectively. These are formed by three layers: an internal gastrodermis derived from the endoderm, surrounding the gastrovascular cavity, an intermediate matrix called mesoglea, and an external epidermis derived from ectoderm (Lommel et al, 2018;D'Ambra et al, 2021;Zhao et al, 2021). The oral opening of the polyp is surrounded by tentacles, suitable for capturing the prey since heterotrophy is required to adequately supply nutrients for some species when photosymbiotic partners do not sufficiently supply the nutritional requirement (Arai, 1997;Goldberg, 2018).…”

Influence of in situ temperature and maternal provisioning on the medusa-to-polyp transition in a year-round population of the scyphozoan Aurelia aurita

“…In seeking to understand jellyfish population dynamics, the majority of work on life histories and reproduction has focused on medusae (Lucas, 1996; Pitt and Kingsford, 2003; Albert, 2005), or polyps (Fuchs et al ., 2014; Widmer et al ., 2016). From this, it appears that the polyp life stage, which displays a high degree of plasticity in its reproductive modes (D'Ambra et al ., 2021; Wang et al ., 2023), plays a critical role in maintaining jellyfish populations and is key to the formation of true blooms (Lucas et al ., 2012; Lucas and Dawson, 2014; Sukhoputova and Kraus, 2017). In contrast to these two ‘adult’ life stages, the planula larva is relatively understudied.…”

‘Conga lines’ of Ediacaran fronds: insights into the reproductive biology of early metazoans

“…Mixed reproductive strategies may manifest in a number of ways. For example, a single organism may employ multiple reproductive modes either simultaneously, or throughout its lifespan [ 3 , 4 ]. Alternatively (and often in addition), reproductive mode may be controlled by phenotypic plasticity [ 1 , 4 ]: the production of varied phenotypes from a genotype in response to different environmental cues.…”

“…For example, a single organism may employ multiple reproductive modes either simultaneously, or throughout its lifespan [ 3 , 4 ]. Alternatively (and often in addition), reproductive mode may be controlled by phenotypic plasticity [ 1 , 4 ]: the production of varied phenotypes from a genotype in response to different environmental cues. The abundant presence of mixed reproductive strategies in the earliest diverging phyla may suggest that the first animals also exhibited mixed reproductive strategies.…”