The term MEDUSAN is a synonym for the word JELLYFISH. It is derived from the Greek mythological figure Medusa, who was a female monster with snakes for hair. The term is used to describe any of the numerous species of JELLYFISH that inhabit the world's oceans. JELLYFISH are invertebrates that have a gelatinous body and tentacles that contain stinging cells. They are found in all oceans and can range in size from a few millimeters to several meters in diameter.