[2] This species is found worldwide in the warm waters of tropical and temperate seas, floating at the surface.

[3] 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.

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.

[6] The air bubbles are stabilized by the secretion of amphiphilic mucins which have evolved from epitoniid egg masses.

[8] 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.