| Limnomedusae | |
|---|---|
 | |
| Olindias formosa | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Subclass: | Trachylinae |
| Order: | Limnomedusae Kramp, 1938 |
Limnomedusae is an order of hydrozoans.
| Limnomedusae | |
|---|---|
| | |
| Olindias formosa | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Subclass: | Trachylinae |
| Order: | Limnomedusae Kramp, 1938 |
Limnomedusae is an order of hydrozoans.
The taxon was erected by Danish marine biologist Paul Lassenius Kramp in 1938 to accommodate certain families of hydrozoans with biphasic life histories. It includes genera with medusae with ecto-endodermal statocysts and with gonads alongside their radial canals, and also genera which have polyps that are not covered by a theca. Molecular analysis performed by Collins in 2006 has since shown that the Limnomedusae are not monophylic. The family Armorhydridae, which contains a single genus and a single species, Armorhydra janowiczi , is found living in coarse sediment, has hollow tentacles and has no radial canals. It seems to share few morphological features with the other families and probably belongs elsewhere. The inclusion of Microhydrulidae is also dubious. The medusa stage is not known and the tiny polyp has no tentacles nor mouth.[ citation needed ]
The World Register of Marine Species currently lists the following families and genera: [1]
Hydrozoa are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most living in salt water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in fresh water. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria.
Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply Velella.
Gonionemus is a genus of hydrozoans that uses adhesive discs near the middle of each tentacle to attach to eelgrass, sea lettuce, or various types of algae instead of swimming. They are small and hard to see when hanging onto swaying seaweed. Nevertheless, they are capable of swimming when necessary. The bell is transparent, revealing the four orange to yellowish-tan gonads that lie along most of the length of the four radial canals. The pale yellow manubrium has four short, frilly lips. Up to 80 tentacles line the bell margin, with about an equal number of statocysts. Copepods are a favored prey.
Rhacostoma is a genus of aequoreid hydrozoans. It is monotypic with a single species, Rhacostoma atlanticum. It has been reported from the Atlantic coastline of North America, Colombia, western and central Africa. The polyp stage is unknown.
Trachymedusae belong to the phylum Cnidaria and the class Hydrozoa, among the 30 genera are 5 families containing around 50 species in all, the family Rhopalonematidae has the greatest diversity.
Anthoathecata, or the athecate hydroids, are an order of hydrozoans belonging to the phylum Cnidaria. A profusion of alternate scientific names exists for this long-known, heavily discussed, and spectacular group. It has also been called Gymnoblastea and, Anthomedusa,Athecata, Hydromedusa, and Stylasterina. There are about 1,200 species worldwide.
Leptothecata, or thecate hydroids, are an order of hydrozoans in the phylum Cnidaria. Their closest living relatives are the athecate hydroids which are similar enough to have always been considered closely related, and the very apomorphic Siphonophora which were placed outside the "Hydroida". Given that there are no firm rules for synonymy for high-ranked taxa, alternative names like Leptomedusa, Thecaphora or Thecata, with or without the ending emended to "-ae", are also often used for Leptothecata.
Narcomedusae is an order of hydrozoans in the subclass Trachylinae. Members of this order do not normally have a polyp stage. The medusa has a dome-shaped bell with thin sides. The tentacles are attached above the lobed margin of the bell with usually a gastric pouch above each. There are no bulbs on the tentacles and no radial canals. Narcomedusans are mostly inhabitants of the open sea and deep waters. They can be found in the Mediterranean in large numbers.
Pandeidae is a family of hydroids in the class Hydrozoa. Like other jellyfish there is usually a mature medusa form which is pelagic and reproduces sexually and a hydroid or polyp form which is often benthic and reproduces asexually by budding.
Cuninidae is a family of hydrozoans in the order Narcomedusae. They have dome-shaped bells and tentacles set above the undulating margin of the bell. Their gastric pouches contain the gonads situated in line with the tentacles, the number of pouches being the same as the number of tentacles. The pouches do not extend below the points of origin of the primary tentacles. Members of some genera have a peripheral canal system and others do not. No radial canals or secondary tentacles are present.
Solmarisidae is a family of hydrozoans in the order Narcomedusae. The name is sometimes spelled "Solmaridae".
Olindiidae is a family of hydrozoans in the order Limnomedusae. They have a polyp phase and a medusa phase. The polyps are generally small (1 mm) and solitary, but a few species are colonial. They have a varying number of tentacles and can reproduce by budding. In the largest species, the medusae can grow to 15 cm (6 in). Centripetal canals may be present or absent and the radial canals are unbranched. The gonads are beside the radial canals, except in Limnocnida, where they are on the manubrium. The fertilised eggs develop into planula larvae which become polyps. These multiply asexually or can bud off medusae. In some species, medusae are only produced when the water temperature exceeds a certain level. Most species are marine, but several can also be found in brackish water and a few, notably Craspedacusta and Limnocnida, are found in fresh water.
Olindias is a genus of hydrozoans in the family Olindiidae.
Gonionemus vertens, the clinging jellyfish, is a small species of hydrozoan in the family Olindiidae found in coastal regions throughout large parts of the Northern Hemisphere.
Aequorea is a genus of pelagic hydrozoans in the family Aequoreidae.
Sertulariidae is a family of hydrozoans.
Maeotias is a genus of hydrozoans in the family Olindiidae. It is a monotypic genus with only a single species, Maeotias marginata, commonly known as the Black Sea jellyfish or brackish water hydromedusa and often referred to as Maeotias inexpectata in the literature. It was first described from the Don and Kuban estuaries of the Sea of Azov, and also occurs in the Black Sea, all of which are areas of low salinity. It has been recorded in several other estuarine locations around the world and is regarded as an invasive species.
Liriope is a genus of hydrozoan in the family Geryoniidae. It contains only one species, Liriope tetraphylla.
Filifera is a suborder of hydrozoans in the order Anthoathecata. They are found in marine, brackish and freshwater habitats.
Microhydrulidae is a family of cnidarians belonging to the order Limnomedusae.
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