Histomorphological comparison of testes in species of box jellyfish (Cnidaria; Cubozoa): does morphology differ with mode of reproduction and fertilization?

Reproductive and environmental traits explain the variation in egg size among Medusozoa (Cnidaria)

“…Indeed, our study corroborates that species with extrernal fertilization more often produces a higher number of eggs [84], while we found no support for internal fertilization being associated with the production of fewer eggs, as suggested before [85]. This, however, may reflect insufficient data on egg size of species with internal fertilization, and highlights the need for additional studies on reproductive patterns in Medusozoa, especially considering that several species are thought to present internal fertilization, even though most inferences are based on indirect evidence [86,87]. In a scenario in which external fertilization is usually considered as a primitive character [41], Medusozoa presents a high diversity and complexity of reproductive traits when compared to other basal Metazoa, and, given the few studies, a high potential for the discovery of additional complex reproductive traits.…”

Histological Investigation of the Female Gonads of Chiropsalmus quadrumanus (Cubozoa: Cnidaria) Suggests Iteroparous Reproduction

“…The accumulated knowledge on the sexual reproduction of cubomedusae is derived from seminal lab studies on five species of Carybdeida (Alatina alata (Reynaud, 1830) [3,11,12]; Carybdea marsupialis (Linnaeus, 1758) [13]; Copula sivickisi (Stiasny, 1926) [12,[14][15][16][17]; Morbakka virulenta (Kishinouyea, 1910) [18]; Tamoya haplonema F. Müller, 1859 [19,20]) and two species of Chirodropida (Chironex fleckeri Southcott, 1956 [21,22], and Chiropsalmus quadrumanus (F. Müller, 1859) [19]). The sexual behaviors of a few species have been described from the field (e.g., [3,23,24]) or from tank observations (e.g., [15,25]), proving the difficulty of performing in situ observations as cubomedusae are active swimmers [26,27] with long tentacles and the ability to avoid obstacles [27] using their complex eyes [28,29].…”

“…However, the scattered knowledge about carybdeid species makes it difficult to establish either semelparity or iteroparity as a universal pattern at the level of class or even order. For example, A. alata medusae reproduce during monthly spermcasting aggregations in which the entire gonad tissue ruptures and the reproductive cells are released [36]; it may be unique among cubozoans as a semelparous species (for references on iteroparous cubomedusae, see [19,20]).…”

“…Recent histomorphological studies have elucidated spermatogenesis in several species of cubomedusae [19,20], but studies concerning oogenesis are limited to C. marsupialis [13] and C. sivickisi (as Carybdea sivickisi [15,17]). Most recently, oogenesis was reported in Carybdea murrayana Haeckel, 1880 (as Carybdea branchi [45]) from southern African waters, and a "maturation scale" for female sex cells was established for the first time in the class.…”

“…Herein, we report on the hitherto obscure reproductive strategy of the chirodropid species C. quadrumanus (Chirodropida, Chiropsalmidae), a relatively common species in the western tropical Atlantic from Brazil to the USA [46][47][48][49][50]. Chiropsalmus quadrumanus is represented by conspicuous cubomedusae (with a bell height of 10 cm and a width of 12 cm on average) which are poorly studied; for instance, a mere three sightings have been reported in the literature in the past decade [19,20,51]. This species' mode of fertilization was previously suggested to be external [19,20], but no evidence supports this claim as the life cycle and cubopolyp location in nature remain undetermined.…”