Janthina

Janthina
A unknown Janthina species with a large bubble raft made from snail mucus.
A drawing of a live Janthina janthina with its bubble raft intact
A drawing of a live Janthina janthina with its bubble raft intact
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Caenogastropoda
Order: incertae sedis
Superfamily: Epitonioidea
Family: Epitoniidae
Genus: Janthina
Röding, 1798
Species

See text

Synonyms
  • Achates Gistel, 1848 (unnecessary substitute name for Janthina)
  • † Acrybia (Hartungia) Bronn, 1861
  • Amethistina [sic] (misspelling for Ametistina Schinz, 1825)
  • Ametistina Schinz, 1825 (suppressed by ICZN Opinion 989)
  • † Hartungia Bronn, 1861
  • † Heligmope Tate, 1893
  • Ianthina (Ianthina is an emendation or an incorrect subsequent spelling of Janthina. It was used indifferently with Janthina by 19th century authors and has remained sporadically in use throughout the 20th century.)
  • Ianthina (Iodina) Mörch, 1860
  • Iodes Mörch, 1860
  • Iodina Mörch, 1860
  • Janthina (Achates) Gistel, 1848
  • Janthina (Iodes) Mörch, 1860
  • Janthina (Iodina) Mörch, 1860
  • Janthinus Montfort, 1810 (unjustified emendation of Janthina)
  • Jantina [sic] (misspelling)
  • † Kaneconcha Kaim, Tucholke & Warén, 2012
  • † Parajanthina Tomida & Itoigawa, 1982 †
  • Violetta Iredale, 1929

Janthina is a genus of small to medium-sized pelagic or planktonic sea snails that belongs to the family Epitoniidae. Species in this genus occur worldwide in tropical, subtropical and warm seas.

The common names for this genus derive from the light purple or violet color of the shells and the violet-colored bodies. The other genera in the family, Recluzia, has olive-tan colored shells.

Description

They are small to medium sized and their shells and bodies often have a light purple to violet coloration. These snails do not have an operculum.

Behavior

This genus exhibits hermaphroditism meaning that they produce both male and female gametes.

These snails are frequently washed ashore during storms.

Raft

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. 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 evolution of their rafts start with the proto-janthinid ancestor which was benthic with females tethering egg masses with associated males. Then these eggs become buoyant.

Diet

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, they feed on the genus Velella (by-the-wind sailor) however some species, such as J. janthina, feed on it along with other jellyfishes such as Physalia physalis (Portuguese man o' war) while other species such as J. pallida prey solely on Velella.

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:

Species brought into synonymy

References

  1. 1 2 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. ↑ Beu, Alan G. (2017). "Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae)". Records of the Australian Museum. 69 (3): 119–222. doi:10.3853/j.2201-4349.69.2017.1666.
  3. ↑ Calabrò, Concetta; Rindone, Antonino; Bertuccio, Clara; Giacobbe, Salvatore (2019-05-01). "Hermaphroditism in a violet snail, Janthina pallida (Gastropoda, Caenogastropoda): a contribution". Biologia. 74 (5): 509–513. doi:10.2478/s11756-018-00177-9. ISSN 1336-9563.
  4. ↑ Morrison, Sue; Storrie, Ann (1999). Wonders of Western Waters: The Marine Life of South-Western Australia. CALM. p. 68. ISBN 0-7309-6894-4.
  5. ↑ Lalli, Carol M.; Ronald W. Gilmer (1989). Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. Stanford University Press. ISBN 978-0-8047-1490-7.
  6. ↑ Churchill, Celia K. C.; Ó Foighil, Diarmaid; Strong, Ellen E.; Gittenberger, Adriaan (2011-10-11). "Females floated first in bubble-rafting snails". Current Biology. 21 (19): R802–R803. doi:10.1016/j.cub.2011.08.011. ISSN 0960-9822.
  7. ↑ "In bubble-rafting snails, the eggs came first". University of Michigan News. 2011-10-10. Retrieved 2026-03-07.
  8. ↑ Helm, Rebecca R. (2021-12-14). "Natural history of neustonic animals in the Sargasso Sea: reproduction, predation, and behavior of Glaucus atlanticus, Velella velella, and Janthina spp". Marine Biodiversity. 51 (6): 99. doi:10.1007/s12526-021-01233-5. ISSN 1867-1624.
  9. ↑ 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