Medusozoa

Hydrozoa (hydrozoans; from Ancient Greek ('''') 'water' and ('''') 'animals') is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline 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 freshwater habitats. Hydrozoans are related to jellyfish and corals, which also belong to the phylum Cnidaria.

thumb|Fossilized stranded scyphozoans on a Cambrian tidal flat at Blackberry Hill, Wisconsin. The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or "true jellies").

class of cnidarians

Medusozoa is a clade in the phylum Cnidaria, and is often considered a subphylum. It includes the classes Hydrozoa, Scyphozoa, Staurozoa and Cubozoa. Medusozoans are distinguished by having a medusa stage in their often complex life cycle, a medusa typically being an umbrella-shaped body with stinging tentacles around the edge. With the exception of some Hydrozoa (and Polypodiozoa), all are called jellyfish in their free-swimming medusa phase. ==Naming== The Medusozoa are named after Medusa from ancient Greek mythology.

species of cnidarian

Staurozoa is a class of Medusozoa (or jellyfish). It has one extant order: Stauromedusae (stalked jellyfishes) with a total of 50 known species. A fossil group called Conulariida has been proposed as a second order, although this is highly speculative. This extinct order is largely unknown and described as a possibly cnidarian clade of marine life with shell-like structures. Staurozoans are small animals () that live in marine environments, usually attached to seaweeds, rocks, or gravel. They have a large antitropical distribution, a majority found in boreal or polar, near-shore, and shallow w

Auroralumina (from Latin aurōra "dawn", lūmina "lights") is a genus of cnidarian from the Ediacaran of Charnwood Forest, comprising the single species Auroralumina attenboroughii. It is the earliest known crown-group cnidarian, and also the earliest known animal predator.

REDIRECT Polypodium hydriforme