Remaining undigested by the medusa , the small snail will devour its host from within, growing larger as its host is correspondingly diminished in size.
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.
A medusa , or jellyfish, is part of the life cycle of just one major group of animals, the cnidarians.
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.
Noteably, all epipelagic, midwater, and deepsea medusae have very simple, reduced, or absent ocelli.
Predation by an abundance of medusae on zooplankton and ichthyoplankton could affect the North Sea ecosystem through top-down and bottom-up mechanisms.
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.
In polyps, medusae , and worms, all longitudinal and circumferential muscles attach to the thin body wall over a wide area.