|A drawing of a live Janthina janthina with its bubble raft intact|
Species in this genus occur worldwide in tropical, subtropical and warm seas.
These snails are pelagic and live at the surface of the ocean. Adult snails may not be capable of swimming, and die when they are detached from their rafts; Janthina janthina larvae, however, actively swim in the water column.
The adult snails prey upon (and live near to) one of several species of pelagic animals loosely known as jellyfish. More specifically they eat the medusae of free-swimming Cnidaria, in particular the genus known as "by-the-wind sailors", Velella.
The snails are able to float securely because they create a raft of clear chitin around air bubbles formed near the ocean surface. They anchor to this raft using their foot. The snails do not have an operculum.
These snails are frequently washed ashore during storms.
The common names for this genus derive from the light purple or violet color of the shells and the violet-colored bodies. The other genus in the family, Recluzia, has olive-tan colored shells.
This genus has accumulated a very large number of species names over the centuries. Most of the names that have been given are in fact synonyms of just a few species which have world-wide distributions in tropical waters. Experts disagree about some details of the synonymy.
Species within the genus Janthina include:
- Janthina exigua Lamarck, 1816 - dwarf janthina
- Janthina globosa Swainson, 1822
- Janthina janthina (Linnaeus, 1758)
- Janthina pallida W. Thompson, 1840
- Janthina umbilicata d'Orbigny, 1841
|Wikimedia Commons has media related to Janthina.|
- Gofas, S. (2011). Janthina Röding, 1798. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138092 on 2011-11-01
- Lalli, Carol M.; Ronald W. Gilmer (1989). Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. Stanford University Press. ISBN 978-0-8047-1490-7.
- Morrison, Sue; Storrie, Ann (1999). Wonders of Western Waters: The Marine Life of South-Western Australia. CALM. p. 68. ISBN 0-7309-6894-4.
- Gofas, S. (2009). Janthina Röding, 1798. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2009) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138092 on 2010-05-16
- Gary Rosenberg's Malacolog 4.1.1 info on this genus in the Western Atlantic
- Laursen, D. 1953. The genus Ianthina: A monograph. Dana Report 38: 1-40, pl. 1