Janthina

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Janthina
Janthina janthina.jpg
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
informal group Ptenoglossa

Superfamily: Epitonioidea
Family: Janthinidae
Genus: Janthina
Röding, 1798
Species

See text

Synonyms[1]
  • Ianthina Röding, 1798
  • Iodes Mörch, 1860
  • Iodina Mörch, 1860

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]

Distribution[edit]

Species in this genus occur worldwide in tropical, subtropical and warm seas.

Description[edit]

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.

Species[edit]

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]

References[edit]

  1. ^ 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
  2. ^ a b Lalli, Carol M.; Ronald W. Gilmer (1989). Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. Stanford University Press. ISBN 978-0-8047-1490-7. 
  3. ^ Morrison, Sue; Storrie, Ann (1999). Wonders of Western Waters: The Marine Life of South-Western Australia. CALM. p. 68. ISBN 0-7309-6894-4. 
  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