Comb Jelly

Technically, though, the bloodbelly comb jelly isn't even related to jellyfish. They do not have the famous stinging tentacles and are harmless to humans. But what they lack in tentacles they make up for in cilia, tiny hair-like projections they beat back and forth to help propel it through the water. It is the movement of this cilia that creates the colorful light show.

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.

Although this animal has a translucent almost colorless body, it frequently presents a real color show. 

The moving cilia refract ambient light into all colors of the rainbow and bright fluorescent stripes are visible on the body. Many ctenophores are bioluminescent, including this species, and at night soft green or blue-green light may be observed.

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. 

This comb jelly is a voracious carnivore and a major predator of edible zooplankton consuming up to 10 times its weight per day. 

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 percent water (no bones or shells to weigh it down).