Cnidaria, phylum Cnidaria, Coelenterata, phylum Coelenterata

hydras; polyps; jellyfishes; sea anemones; corals

• phylum — (biology) the major taxonomic group of animals and plants; contains classes

• coelenterate, cnidarian — radially symmetrical animals having saclike bodies with only one opening and tentacles with stinging structures; they occur in polyp and medusa forms
• polyp — one of two forms that coelenterates take e.g. a hydra or coral: usually sedentary and has a hollow cylindrical body usually with a ring of tentacles around the mouth
• medusa — one of two forms that coelenterates take: is the free-swimming sexual stage in the life cycle of a coelenterate and has a gelatinous umbrella-shaped body and tentacles
• Scyphozoa, class Scyphozoa — coelenterates in which the polyp stage is absent or at least inconspicuous: jellyfishes
• jellyfish, medusa, medusan — any of numerous usually marine and free-swimming coelenterates that constitute the sexually reproductive forms of hydrozoans and scyphozoans
• Hydrozoa, class Hydrozoa — coelenterates typically having alternation of generations; hydroid phase is usually colonial giving rise to the medusoid phase by budding: hydras and jellyfishes
• Anthozoa, class Anthozoa, Actinozoa, class Actinozoa — no alternation of generations the medusoid phase being entirely suppressed: sea anemones; corals

• Metazoa, subkingdom Metazoa — multicellular animals having cells differentiated into tissues and organs and usually a digestive cavity and nervous system