Scyphozoa

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Scyphozoa

[‚sī·fə′zō·ə]
(invertebrate zoology)
A class of the phylum Cnidaria; all members are marine and are characterized by large, well-developed medusae and by small, fairly well-organized polyps.

Scyphozoa

 

a class of solitary marine animals of the phylum Coelenterata. Scyphozoans occur in the form of jellyfish or polyps and are radially symmetrical. The gastric cavity is divided by interradial mesenteries into a central cavity and lateral pouches. Many scyphomedusae have a system of digestive canals. The life cycle is characterized by alternating generations (metagenesis). A planula larva develops from an egg and, after settling on a substrate, becomes a scyphistoma, an individual of the polypoid generation. The scyphistoma buds off polyps like itself and releases ephyrae (larvae of the sexually reproducing generation) by constriction (strobilation).

Bodily contact with certain scyphozoans, for example, Rhizostomae, may cause pain and skin burns. Persons have been known to die after being poisoned by individuals of the genus Chirodrophus, which dwell off northern Australia. Some scyphozoans, for example, Rhizostomae and Aurelia, are commercially significant; they are salted and used as food.

The class of Scyphozoa, comprising the orders Discomedusae, Rhizostomae, Coronatae, and Stauromedusae, includes approximately 200 species, which are distributed throughout the oceans of the world, mostly in temperate and tropical waters. Approximately 30 species occur in the USSR.

REFERENCES

Naumov, D. V. Stsifoidnye meduzy morei SSSR. Moscow-Leningrad, 1961.
Bronns, H. G. Klassen und Ordnungen des Tierreichs, vol. 2, part 2, fascs. 1–6. Leipzig, 1936–59.
Kramp, P. L. Synopsis of the Medusae of the World. Cambridge, 1961.

D. V. NAUMOV

References in periodicals archive ?
Population-level perspectives on global change: genetic and demographic analyses indicate various scales, timing, and causes of scyphozoan jellyfish blooms.
The scyphozoan solution involves the use of such a diffuse, non-polarized nerve net for distribution of motor commands (Mayer, 1910; Bozler, 1926a, b; Horridge, 1956a).
Since the statolith of both scyphozoan and cubozoan rhopalia is not organized into a recognizable statocyst-like structure, it is possible that the statolith functions as a weight to maintain a specific rhopalial orientation independent of orientation of the medusa, as demonstrated by Garm et al.
Induction of metamorphosis in the symbiotic scyphozoan Cassiopea andromeda: a role of marine bacteria and of biochemicals.
The morphological diversity of pelagic scyphozoan orders originated during the Cambrian (Willoughby and Robison, 1979; Hagadorn et al.
However, recent phylogenetic analyses of Cnidaria based on morphology (Marques and Collins, 2004) and molecular data (Collins, 2002) suggest that Stauromedusae is not more closely related to the scyphozoan taxa Coronatae, Rhizostomeae, and Semaeostomeae (herein united as Scyphozoa, following Marques and Collins, 2004) than it is to Cubozoa or Hydrozoa.
For example, at the Monterey Bay Aquarium, the scyphozoans Mastigias papua and Cassiopeia xamachana have been reared for several months in tanks with metal halide and actinic or daylight fluorescent lamps.
scyphozoans, janthinid snails, Nautilus) (Hamner, 1996).
Aurelia has a typical bipartite scyphozoan life history in which benthic scyphopolyps asexually strobilate ephyrae that grow into sexual medusae, the females of which brood larvae that settle into the shallow coastal benthos within a few days of being released.
microadriaticum that had been extracted and cultured from a scyphozoan host described as Cassiopeia sp.
In a recent study, the luminescence of the scyphozoan jellyfish Periphylla periphylla was found to be associated with two distinct sources: one represented by minute, irregularly shaped cytoplasmic granules in the cortical layer of maturing ovarian eggs; the other represented by clusters of even smaller, mostly spherical grains within the cytoplasm of highly specialized photocytes that are less than 1 mm apart and distributed throughout the exumbrellar epithelium of the medusae (Herring, 1990; Flood et al.
brevispinum are also concentrated in these regions, then the arm spine tips may be the primary sensory regions of the animal, similar to rhopalia in scyphozoans or asthaetes in polyplacophorans.