Janthina
| Janthina | |
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| A drawing of a live Janthina janthina with its bubble raft intact | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| (unranked): | clade Caenogastropoda clade Hypsogastropoda |
| Superfamily: | Epitonioidea |
| Family: | Janthinidae |
| Genus: | Janthina Röding, 1798 |
| Species | |
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| Synonyms[1] | |
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Janthina is a genus of small to medium-sized pelagic or planktonic sea snails, marine gastropod molluscs in the family Janthinidae, commonly known as the "purple snails" or the "violet shells". [1]
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[edit] Distribution
Species in this genus occur worldwide in tropical, subtropical and warm seas.
[edit] Description
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.[2]
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.[2] The snails do not have an operculum.
These snails are frequently washed ashore during storms.[3]
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.
[edit] Species
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:[4]
- Janthina exigua Lamarck, 1816 - dwarf janthina
- Janthina globosa Swainson, 1822
- Janthina janthina (Linnaeus, 1758)
- Janthina pallida W. Thompson, 1840
- Janthina umbilicata d'Orbigny, 1841
[edit] References
- ^ a b 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
- ^ a b Lalli, Carol M.; Ronald W. Gilmer (1989). Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. Stanford University Press. ISBN 9780804714907.
- ^ Morrison, Sue; Storrie, Ann (1999). Wonders of Western Waters: The Marine Life of South-Western Australia. CALM. pp. 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
