/ məˈdoōsə; -zə/
/ -sē; -sī; -zē; -zī/ or -sas
a free-swimming sexual form of a coelenterate such as a jellyfish, typically having an umbrella-shaped body with stinging tentacles around the edge. In some species, medusae are a phase in the life cycle that alternates with a polypoid phase. Compare with polyp.
The free-swimming stage in the life cycle of the Cnidaria
. Medusae are umbrella-shaped, with tentacles round the edge and the mouth in the centre underneath. They swim by pulsations of the body and reproduce sexually. In the Hydrozoa (e.g. Hydra
) they alternate in the life cycle with polyps
, from which they are produced by budding. In the Scyphozoa, which includes all the common jellyfish, the medusa is the dominant form and the polyp is reduced or absent.
A ‘jellyfish’; in Cnidaria
, the free-swimming body type, resembling an umbrella or bell, that floats convex side uppermost. The mouth is located at the centre of the under-side of the bell and tentacles
hang from its edge.
medusa (in zoology)
medusa, in zoology, scientific name for the jellyfish, i.e., the free-swimming stage of various animals in the phylum Cnidaria. See polyp and medusa.