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 which alternates with a polypoid phase.Compare with polyp‘A medusa, or jellyfish, is part of the life cycle of just one major group of animals, the cnidarians.’
- ‘Cnidarians have two basic body forms, medusa and polyp.’
- ‘Two major adult body types characterize the phylum: the medusa is typically a mobile pelagic organism, and the polyp is typically a sessile benthic organism.’
- ‘Scyphozoan polyps and medusae exhibit no cephalization and contain no brain, but in some species, light-sensitive eyespots are located along the bell margin of the medusa.’
- ‘In polyps, medusae, and worms, all longitudinal and circumferential muscles attach to the thin body wall over a wide area.’
- 1.1A jellyfish.‘In studies with a microscope, Forbes had shown that hydroid jellyfish known as naked-eyed medusae reproduce not only by spewing eggs, but also by asexual budding, which he found marvelous to behold.’
- ‘This specialized tank creates a waterflow that keeps medusae and other delicate animals in constant suspension assuring that their tissues are not destroyed by abrasive contact with aquarium walls.’
- ‘Noteably, all epipelagic, midwater, and deepsea medusae have very simple, reduced, or absent ocelli.’
- ‘Remaining undigested by the medusa, the small snail will devour its host from within, growing larger as its host is correspondingly diminished in size.’
- ‘Predation by an abundance of medusae on zooplankton and ichthyoplankton could affect the North Sea ecosystem through top-down and bottom-up mechanisms.’
Mid 18th century named by association with Medusa.
proper nounGreek Mythology
The only mortal gorgon, whom Perseus killed by cutting off her head.