A free-swimming aquatic creature. It starts life as a larva, which attatches itself to a rock or other solid substance and develops into a polyp; eventually the polyp grows into the familiar bell-shaped organism.
Most jellyfish have tentacles and a basic nervous system, though they lack more complicated organs, and they are allegedly composed of about 95% water. They usually catch their prey by brushing potential victims with their poison-spouting, long tentacles, which can be anywhere from inches to several feet long.
Slang: various sex acts.
Sometimes, during low tide, one sees jellyfish lining the shores.
Northeast Atlantic coast: tiny, harmless, translucent sea creatures from two to three inches across that resemble jellyfish but do not actually sting their food.
Southeast Atlantic coast: usually about six to eight inches in diameter, a jellyfish that is mildly venomous and identifiable by its four pink horseshoe-shaped markings.
Northeast Pacific coast: up to about fifteen inches in diameter, a jellyfish that doesn't have the long tentacles usually associated with its kind but a short fringe that sweeps food to its mucous layer right under the bell.
"When I was younger," said Sarah, "I would never go swimming when we went to the beach because I was terrified of finding a moon jelly."