Oocyte development in four species of scyphomedusa in the northern Adriatic Sea

Abstract

Oocyte development was followed in 4 species of Scyphomedusae. In Pelagia noctiluca a centrifugal maturity gradient is present. Vitellogenesis may be related first to exogenous endodermal production and later to oocyte endogenous activity. Simultaneously, the paraovular body (POB) develops from the secondary endoderm; it is connected to the oocyte and controls secretion of mucus, which envelops the oocyte during spawning. In Aurelia aurita, there is no maturity gradient, nor any differentiated structures of endodermal origin, associated with oocytes. In Discomedusa lobata a maturity gradient is absent. Its vitellogenesis is similar to that in P. noctiluca, and is associated with structural modification of the secondary endoderm in the area contacting the oocyte. This structure is cytologically similar to the POB of P. noctiluca, though less differentiated. Spawning is similar to that of P. noctiluca, with fenestration of the surrounding endodermal cells as the oocyte passes from the ovary to the genital sinus. In Rhizostoma pulmo a maturity gradient is absent. An early and fairly evident development of the vitelline membrane was observed.

New observations on the asexual reproduction of Aurelia aurita (Cnidaria: Scyphozoa) with comments on its life cycle and adaptive significance /

“…Oogenesis is asynchronous, without a maturation gradient, and oogonia differentiate without a pattern within the endoderm. There is a high degree of variability in oocyte and planula larvae size composition within populations; yolk deposition starts in oocytes of about 75 µm in diameter, and mature oocytes range between about 75 and 180 µm (Widersten, 1965;Eckelbarger, Larson, 1988;Avian, Sandrini, 1991;Lucas, Lawes, 1998).…”

Probabilistic modeling to estimate jellyfish ecophysiological properties and size distributions

“…For the sake of model validation, the best parameter values found by the SMCE are comparable to the ones that have been found previously, therefore confirming those isolated observations. Concerning reproduction processes, the spawning behavior of P. noctiluca has been widely studied 26,29,34,51 showing that all sexually mature organisms spawned daily until their death. This gamete emission occurs 3 hours after the start of the light and for 30 minutes.…”

“…Our new model parameterized with SMCE suggested that an almost daily spawning frequency is optimal for error minimization both in the laboratory and field conditions. Spawning activation was mostly discussed for the species P. noctiluca, but spawning among scyphozoans seems to be related to environmental stress such as light variations 34,[52][53][54][55] temperature 56 , and food availability 26,56 . Our model supposed that mucus production during spawning represented respectively 67.5%, 62.5%, and 67.5% of total spawn in the laboratory, in situ, and both conditions compared to literature, which estimated at 52% 34 .…”

“…Moreover, this species can realize nycthemeral migrations between 0 and 300-500 m deep. The development of the jellyfish P. noctiluca from oocyte to adult is strongly related to temperature and environmental food conditions [25][26][27][28][29][30] . It is a non-specific predator 21 that responds rapidly to changes in the biotic and abiotic environment 31,32 .…”

Gametogênese e desenvolvimento embrionário de Nausithoe aurea (Scyphozoa, Coronatae) do canal de São Sebastião - SP.

“…Franzén (1996) (Fautin & Mariscal, 1991). Os trofócitos foram denominados células subsidiárias ("nurse cells") por Widersten (1965), e corpo paraovular ("paraovular body") por Avian & Rottini Sandrini (1991). O trofonema dos antozoários executa um papel nutritivo durante a vitelogênese canalizando nutrientes da cavidade gastrovascular para o oócito, e um papel similar é hipotetizado para os trofócitos de medusas de Semaeostomeae e Rhizostomeae (Eckelbarger & Larson, 1988 Scyphozoa, a origem gastrodérmica das células germinativas é uma razão que sugere uma íntima relação filogenética entre as duas classes (Thiel, 1966).…”