noun (plural medusae /-sē, -sī, -zē, -zī/ or medusas)Zoology
1A 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.
- 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.
- 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.
mid 18th century: named by association with Medusa.