Staurozoa is a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

Medusozoa Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Cubozoa, and possibly the parasitic Polypodiozoa. Medusozoans are distinguished by having a medusa sta ...

, jellyfishes and hydrozoans. It has one extant order: Stauromedusae (stalked jellyfishes) with a total of 50 known species. A fossil group called

Conulariida Conulariida is a poorly understood fossil group that has possible affinity with the Cnidaria. Their exact position as a taxon of extinct medusozoan cnidarians is highly speculative. Members of the Conulariida are commonly referred to as conularii ...

has been proposed as a second order, although this is highly speculative. The extinct order is largely unknown and described as a possibly

cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

n clade of marine life with shell-like structures, the

. Staurozoans are small animals () that live in marine environments, usually attached to seaweeds, rocks, or gravel.Collins, A. G. (n.d.). Staurozoa. ''AccessScience''. doi:10.1036/1097-8542.652700 They have a large antitropical distribution, a majority found in boreal or polar, near-shore, and shallow waters. Few staurozoans are found in warmer tropical and subtropical water environments of the Atlantic, Indian, and Pacific Ocean basins, but most are known from the Northern Hemisphere. Over the years their number of species has increased, thus right now it is said to have an estimated 50 species. Information on Staurozoa, is one of the least studied groups within Cnidaria. It is often neglected, but correctly recognizing the characters of this class is crucial for understanding cnidarian evolution.

Morphology

During the metamorphosis of a stauropolyp into an adult stauromedusa, is the eight primary tentacles: # Disappear by resorption. # Metamorphose into adhesive interradial and perradial rhopalioids. # Remain as primary tentacles but with a modified shape. # Migrate and cluster together with the secondary tentacles. Their life cycle is not well known, but is simplistic. They have a lifespan of less than a year and the planua larva attaches to the substrate, developing into a primary (interstitial) polyp that undergoes an apical transformation to develop into its adult body. The bodies consist of a calyx or cup, where they take in their prey with tentacles that contain cnidocysts- stinging cells. The tentacles are clusters on the edge of the body that lie on a stalk that attaches to a benthic substrate with their adhesive basal disk. The color of a Staurozoan depends on where they've attached in their environment.

Ecology

Staurozoans are predators and eat crustaceans such as, harpacticoid copepods for the smaller of the species and gammarid amphipods for the larger of the species. They also eat chironomid fly larvae, as well as plankton and when they're done with their food they eject it from their bodies. They are also preyed upon by fish as well as mollusks.

Gallery

File:Haliclystus stejnegeri 1.jpg, ''Haliclystus sp.'' File:Haliclystus antarcticus 1C.jpg, ''

Haliclystus antarcticus ''Haliclystus'' is a genus of stalked jellyfish Stauromedusae are the stalked jellyfishes. They are the sole living members of the class Staurozoa and belong to the medusozoa subphylum of Cnidaria. They are unique among medusa jellyfish in th ...

'' File: Green subum.jpg, ''

Haliclystus sanjuanensis ''Haliclystus sanjuanensis'' is a species of small (~4 cm) stalked jellyfish found in the Pacific Ocean along the west coast of North America. This species can be found in shallow waters at low tide on soft substrates such as seagrass (''Phy ...

'' File:6 or-Manania handi.tif, ''

Manania handi ''Manania handi'' is a species of stalked jellyfish found in the Pacific Ocean along the west coast of North America. This species can be found in shallow waters at low tide on soft substrates such as seagrass (''Phyllospadix''), but the related ...

References

# Medusozoa Cnidarian taxonomy {{staurozoa-stub