Comb jellies are beautiful, oval-shaped animals with eight rows of tiny comblike plates that they beat to move themselves through the water. As they swim, the comb rows diffract light to produce a shimmering, rainbow effect. Voracious predators on other jellies, some can expand their stomachs to hold prey nearly half their own size.
Jellies are simple creatures with few specialized organs. Most jellies can detect chemical traces in the water that allow them to locate food, and many are equipped with a gravity-sensitive structure, called a statocyst, that gives them a sense of up and down in the water.
Jellies can be very sensitive to water quality during certain points in their life cycle. Changes in the health of jelly populations may be a tip-off to larger environmental problems.
Alien as it looks, a jelly's soft shape is perfectly adapted to its environment. The animal's thin skin stretches over a body that's more than 95% water (no bones or shells to weigh it down).
Comb jellies will eat other comb jellies larger than themselves by biting off chunks with special cilia structures in their mouths.