Violet Snails - Janthina spp.

Order: Sorbeoconcha (Neotaenioglossa)
Superfamily: Janthinoidea
Family: Janthinidae


The Violet Snail, Janthina, with its float of mucus bubbles floating alongside the siphonophore Physalia on which it feeds. Photo: Bill Rudman

Often washed up on beaches as empty shells, he Violet Snails spend their lives floating at the surface of the open ocean, feeding on the Bluebottle Physalia, and related cnidarians. It floats by producing a mass of mucous bubbles which harden into a bubbleplastic-like float. There are a number of species of the genus Janthina, and most have a worldwide distribution. Like many of the animals living in the surface layers of the sea their colour pattern is a good example of countershading. The underside of their shell (which is on top when they are floating) is much darker in colour than the upperside. This helps to camouflage them both from above and below.

Authorship details
Rudman, W.B., 2002 (April 23) Violet Snails - Janthina spp. . [In] Sea Slug Forum. Australian Museum, Sydney. Available from