Pelagia means occurring in the open ocean; nocti means night and luca means light. In other words, this is an offshore jellyfish that glows in the dark.

This was a small one, but the huge bowl-shaped bells can grown up to 2 feet across, and are pink-to-purple with long, frilly undersides up to 7 feet long.

Pelagia noctiluca has four, maneuverable arms about the same length as its eight trailing tentacles. The arms and tentacles all bear stinging cells, which subdue small animals that run into them. Then, the four arms contract to deliver the prey to the mouth, located under the bell at its center.

The top of Pelagia's bell is covered with spots that are actually clumps of stinging cells. One author reports that after touching one of these bells, he felt pain like tiny pinpricks lasting for about 30 seconds. But beware: The tentacles and arms of this jellyfish can pack a much more powerful punch.

Pelagia noctiluca is found in the surface waters of the North Atlantic, the Mediterranean and the North Pacific. Sometimes, people see these creatures from ships at night, when great numbers of these jellyfish cast off a greenish light as they pulse through the water.