Violet Sea Snail

J. janthina is a member of the family Janthinidae, snails that trap air bubbles to maintain their positions at the surface of the ocean, where they are predators on hydrozoa. The air bubbles are stabilized by the secretion of amphiphilic mucins which have evolved from epitoniid egg masses. This passive flotation is a particularly resource-efficient form of animal locomotion. In addition to the bubble raft, only the veliger, or larval stage, has an operculum, and the shell is paper-thin to allow the animal to float upside down at the surface.

This species is found worldwide in the warm waters of tropical and temperate seas, floating at the surface. More specifically, the species is located in the tropical and subtropical Atlantic, Indian and Pacific oceans. They are often found in large groups and sometimes become stranded on beaches when they are blown ashore by strong winds. The snails are a unique part of the neuston, organisms which live on or near the surface of the water, because of their relatively large size. They have veliger, or free swimming larvae, but the adults do not swim, and cannot create their rafts, except at the surface where air bubbles are available.