Scyphistomae show different modes of propagation, occasionally allowing the sudden release of great numbers of medusae through strobilation leading to so-called jellyfish blooms. Accordingly, factors regulating asexual reproduction strategies will control scyphistoma density, which, in turn, may influence blooming potential. We studied 11 scyphistoma species in 6 combinations of temperature and food supply to test the effects of these factors on asexual reproduction strategies and reproduction rates. Temperature and food availability increased reproduction rates for all species and observed reproduction modes. In all cases, starvation was the most important factor constraining the asexual reproduction of scyphistomae. Differences in scyphistoma density were found according to the reproductive strategy adopted by each species. Different Aurelia lineages and Sanderia malayensis presented a multi-mode strategy, developing up to 5 propagation modes. These species reached the highest densities, mostly through lateral budding and stolons. Cassiopea sp., Cephea cephea, Mastigias papua and Phyllorhiza punctata adopted a mono-mode reproductive strategy, developing only free-swimming buds. Lychnorhiza lucerna, Rhizostoma pulmo and Rhopilema esculentum also presented a mono-mode strategy, but they only developed podocysts. These 3 species had the lowest reproduction rates and polyp densities; not only their reproduction rates but also the need for a 2-fold set of environmental stimuli to produce new polyps (one for encystment, another for excystment) made this reproduction mode the slowest of those observed to be utilized for propagation. We conclude that blooms may be defined phylogenetically by the specific asexual modes each species develops, which, in turn, is regulated by environmental conditions.

ResumoLista dos Cnidaria Medusozoa do Brasil Uma lista dos Cnidaria Medusozoa marinhos do Brasil foi composta a partir de registros de ocorrência disponíveis na literatura. Até o momento, há um total de 373 espécies registradas para o Brazil: 347 de Hydrozoa, 3 de Cubozoa e 23 de Scyphozoa.http://www.biotaneotropica.org.br AbstractChecklist of the Cnidaria Medusozoa from Brazil Literature records were reviewed to compile a list of species of the marine taxa of Cnidaria MedusozoaThe total number of species of medusozoans so far recorded for Brazil is 373: 347 Hydrozoa, 3 Cubozoa: 23 Scyphozoa.recorded for the Brazilian coast.

Revision of the scyphozoan genus Chrysaora Péron & Lesueur, 1810 was undertaken from observations on museum material (Brazil, Europe, and USA), on living specimens in nature, and on life-cycles of some species cultured under laboratory conditions. A total of 168 museum lots, some of them having many medusae, were inspected. Included amongst these were nine type specimens. The genus comprises 13 valid species (Chrysaora achlyos, C. chinensis, C. colorata, C. fulgida, C. fuscescens, C. hysoscella, C. lactea, C. melanaster, C. pacifica, C. pentastoma, C. plocamia, and C. quinquecirrha), one species inquirenda (Chrysaora caliparea), and two doubtful species (C. kynthia and C. wurlerra). Differentiation of species is based mostly on tentacle number, shape of radial septa, order of tentacle development, colouration, and measurements of nematocysts. We resurrect C. chinensis for specimens from southeast Asia. Chrysaora pacifica is considered valid and distinct from C. melanaster based on tentacle number and nematocyst complement. Mediterranean specimens assigned to C. hysoscella are hermaphroditic and thereby considered distinct from those of C. fulgida from west Africa. Chrysaora achlyos (northeast Pacific) and C. plocamia (southeast Pacific and southwest Atlantic) are geographically isolated but morphologically identical, being distinguished only by colour pattern. The recently described C. southcotti is considered a junior synonym of C. pentastoma. The Australian C. kynthia and C. wurlerra, here considered nomina dubia, merit further study. Our phylogenetic hypothesis indicates that the genus Chrysaora forms a monophyletic group, with C. colorata, C. plocamia, and C. achlyos having a basal position in the phylogeny. Species with more than 24 tentacles (formerly assigned to the genus Dactylometra) form a clade with a derived position.

The low evolutionary rate of mitochondrial genes in Anthozoa has challenged their utility for phylogenetic and systematic purposes, especially for DNA barcoding. However, the evolutionary rate of Ceriantharia, one of the most enigmatic “orders” within Anthozoa, has never been specifically examined. In this study, the divergence of mitochondrial DNA of Ceriantharia was compared to members of other Anthozoa and Medusozoa groups. In addition, nuclear markers were used to check the relative phylogenetic position of Ceriantharia in relation to other Cnidaria members. The results demonstrated a pattern of divergence of mitochondrial DNA completely different from those estimated for other anthozoans, and phylogenetic analyses indicate that Ceriantharia is not included within hexacorallians in most performed analyses. Thus, we propose that the Ceriantharia should be addressed as a separate clade.

The upside-down jellyfish Cassiopea xamachana (Scyphozoa: Rhizostomeae) has been predominantly studied to understand its interaction with the endosymbiotic dinoflagellate algae Symbiodinium. As an easily culturable and tractable cnidarian model, it is an attractive alternative to stony corals to understanding the mechanisms driving establishment and maintenance of symbiosis. Cassiopea is also unique in requiring the symbiont in order to complete its transition to the adult stage, thereby providing an excellent model to understand symbiosis-driven development and evolution. Recently, the Cassiopea research system has gained interest beyond symbiosis in fields related to embryology, climate ecology, behavior, and more. With these developments, resources Ohdera et al. Cassiopea xamachana System Review including genomes, transcriptomes, and laboratory protocols are steadily increasing. This review provides an overview of the broad range of interdisciplinary research that has utilized the Cassiopea model and highlights the advantages of using the model for future research.

Jellyfish (primarily scyphomedusae) fisheries have a long history in Asia, where jellyfish have been caught and processed as food for centuries. More recently, jellyfish fisheries have expanded to the Western Hemisphere, often driven by demand from Asian buyers and collapses of more traditional local fish stocks. Jellyfish fisheries have been attempted in numerous countries in North, Central, and South America, with varying degrees of success. Here, we chronicle the arrival of jellyfish fisheries in the Americas and summarize relevant information on jellyfish fishing, processing, and management. Processing technology for edible jellyfish has not advanced, and presents major concerns for environmental and human health. The development of alternative processing technologies would help to eliminate these concerns and may open up new opportunities for markets and species. We also examine the biodiversity of jellyfish species that are targeted for fisheries in the Americas. Establishment of new jellyfish fisheries appears possible, but requires a specific combination of factors including high 123Rev Fish Biol Fisheries DOI 10.1007/s11160-016-9445-y abundances of particular species, processing knowledge dictated by the target market, and either inexpensive labor or industrialized processing facilities. More often than not, these factors are not altogether evaluated prior to attempting a new jellyfish fishery. As such, jellyfish fisheries are currently expanding much more rapidly than research on the subject, thereby putting ecosystems and stakeholders' livelihoods at risk.

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The use of molecular data for species delimitation in Anthozoa is still a very delicate issue. This is probably due to the low genetic variation found among the molecular markers (primarily mitochondrial) commonly used for Anthozoa. Ceriantharia is an anthozoan group that has not been tested for genetic divergence at the species level. Recently, all three Atlantic species described for the genus Isarachnanthus of Atlantic Ocean, were deemed synonyms based on morphological simmilarities of only one species: Isarachnanthus maderensis. Here, we aimed to verify whether genetic relationships (using COI, 16S, ITS1 and ITS2 molecular markers) confirmed morphological affinities among members of Isarachnanthus from different regions across the Atlantic Ocean. Results from four DNA markers were completely congruent and revealed that two different species exist in the Atlantic Ocean. The low identification success and substantial overlap between intra and interspecific COI distances render the Anthozoa unsuitable for DNA barcoding, which is not true for Ceriantharia. In addition, genetic divergence within and between Ceriantharia species is more similar to that found in Medusozoa (Hydrozoa and Scyphozoa) than Anthozoa and Porifera that have divergence rates similar to typical metazoans. The two genetic species could also be separated based on micromorphological characteristics of their cnidomes. Using a specimen of Isarachnanthus bandanensis from Pacific Ocean as an outgroup, it was possible to estimate the minimum date of divergence between the clades. The cladogenesis event that formed the species of the Atlantic Ocean is estimated to have occured around 8.5 million years ago (Miocene) and several possible speciation scenarios are discussed.