Janthina

{{Short description|Genus of gastropods}} {{Automatic taxobox | image = Violet snail Janthina sp.png | image_caption = A unknown Janthina species with a large bubble raft made from snail mucus. | image2 = Janthina janthina.jpg | image2_alt = A drawing of a live Janthina janthina with its bubble raft intact | image2_caption = A drawing of a live ''Janthina janthina'' with its bubble raft intact | image_alt = | display_parents = 2 | taxon = Janthina | authority = Röding, 1798 | subdivision_ranks = Species | subdivision = See text | synonyms_ref = <ref name="WoRMS" /> | 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.<ref name="WoRMS">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</ref><ref>{{cite journal | url=https://doi.org/10.3853/j.2201-4349.69.2017.1666 | doi=10.3853/j.2201-4349.69.2017.1666 | title=Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae) | date=2017 | last1=Beu | first1=Alan G. | journal=Records of the Australian Museum | volume=69 | issue=3 | pages=119–222 | doi-access=free }}</ref>

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.<ref>{{Cite journal |last=Calabrò |first=Concetta |last2=Rindone |first2=Antonino |last3=Bertuccio |first3=Clara |last4=Giacobbe |first4=Salvatore |date=2019-05-01 |title=Hermaphroditism in a violet snail, Janthina pallida (Gastropoda, Caenogastropoda): a contribution |url=https://doi.org/10.2478/s11756-018-00177-9 |journal=Biologia |language=en |volume=74 |issue=5 |pages=509–513 |doi=10.2478/s11756-018-00177-9 |issn=1336-9563}}</ref>

These snails are frequently washed ashore during storms.<ref name="M&S">{{cite book |last=Morrison |first= Sue|author2=Storrie, Ann|title=Wonders of Western Waters: The Marine Life of South-Western Australia |date=1999 |publisher=CALM |isbn=0-7309-6894-4 |pages=68 }}</ref>

=== 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.<ref name="Lalli1989">{{cite book|last=Lalli|first=Carol M.|author2=Ronald W. Gilmer|title=Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks|publisher=Stanford University Press|date=1989|isbn=978-0-8047-1490-7 }}</ref> 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.<ref>{{Cite journal |last=Churchill |first=Celia K. C. |last2=Ó Foighil |first2=Diarmaid |last3=Strong |first3=Ellen E. |last4=Gittenberger |first4=Adriaan |date=2011-10-11 |title=Females floated first in bubble-rafting snails |url=https://www.sciencedirect.com/science/article/pii/S0960982211008864 |journal=Current Biology |volume=21 |issue=19 |pages=R802–R803 |doi=10.1016/j.cub.2011.08.011 |issn=0960-9822}}</ref><ref>{{Cite web |date=2011-10-10 |title=In bubble-rafting snails, the eggs came first |url=https://news.umich.edu/in-bubble-rafting-snails-the-eggs-came-first/ |access-date=2026-03-07 |website=University of Michigan News |language=en-US}}</ref>

=== 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.<ref>{{Cite journal |last=Helm |first=Rebecca R. |date=2021-12-14 |title=Natural history of neustonic animals in the Sargasso Sea: reproduction, predation, and behavior of Glaucus atlanticus, Velella velella, and Janthina spp. |url=https://doi.org/10.1007/s12526-021-01233-5 |journal=Marine Biodiversity |language=en |volume=51 |issue=6 |pages=99 |doi=10.1007/s12526-021-01233-5 |issn=1867-1624|doi-access=free }}</ref>

==Species== <div align=center> The five extant species of the genus ''Janthina'' <gallery mode="packed" heights="130"> File:Janthina exigua 01.jpg|''Janthina exigua'' File:Janthina globosa 01.JPG|''Janthina globosa'' File:Janthina janthina 01.JPG|''Janthina janthina'' File:Janthina pallida 01.JPG|''Janthina pallida'' File:Janthina umbilicata 01.jpg|''Janthina umbilicata'' </gallery> </div align=center>

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:<ref>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</ref> * † ''Janthina chavani'' (Ludbrook, 1978) * ''Janthina exigua'' Lamarck, 1816 - dwarf janthina * ''Janthina globosa'' Swainson, 1822 * ''Janthina janthina'' (Linnaeus, 1758) *† ''Janthina krejcii'' Beu, 2017 * ''Janthina pallida'' W. Thompson, 1840 * † ''Janthina typica'' (Bronn, 1861) * ''Janthina umbilicata'' d'Orbigny, 1841 ;Species brought into synonymy: * ''Janthina affinis'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina africana'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina alba'' Anton, 1838: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina balteata'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina bicolor'' Menke, 1828: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina bicolor'' O. G. Costa, 1830: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina bifida'' Nuttall, 1850: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina britannica'' Forbes & Hanley, 1853: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina capreolata'' Montrouzier, 1860: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina carpenteri'' Mörch, 1860: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina casta'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina coeruleata'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina communis'' Lamarck, 1822: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina contorta'' Carpenter, 1857: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina costae'' Mörch, 1860: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina decollata'' Carpenter, 1857: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina depressa'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina elongata'' [sic]: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina fibula'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina fragilis'' Lamarck, 1801: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina globosa'' Blainville, 1822: synonym of ''Janthina umbilicata'' d'Orbigny, 1840 * ''Janthina grandis'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina incisa'' Philippi, 1848: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina involuta'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina iricolor'' Reeve, 1858: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina jehennei'' (Petit de la Saussaye, 1853): synonym of ''Recluzia jehennei'' Petit de la Saussaye, 1853 * ''Janthina laeta'' Monterosato, 1884: synonym of ''Janthina pallida'' W. Thompson, 1840 * ''Janthina megastoma'' A. Adams, 1861: synonym of ''Janthina umbilicata'' d'Orbigny, 1840 * ''Janthina nana'' Gray, 1842: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina nitens'' Menke, 1828: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina nitida'' A. Adams, 1861: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina orbignyi'' Mörch, 1860: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina patula'' Philippi, 1844: synonym of ''Janthina pallida'' W. Thompson, 1840 * ''Janthina payraudeaui'' Locard, 1900: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina penicephela'' Peron, 1824: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina planispirata'' A. Adams & Reeve, 1848: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina prolongata'' Blainville, 1822: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina rosea'' Anton, 1838: synonym of ''Janthina pallida'' W. Thompson, 1840 * ''Janthina roseala'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina roseola'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina rotundata'' Dillwyn, 1840: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina smithiae'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina splendens'' Monterosato, 1884: synonym of ''Janthina globosa'' Swainson, 1822 * ''Janthina striata'' Montrouzier, 1860: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina striolata'' A. Adams & Reeve, 1848: synonym of ''Janthina pallida'' W. Thompson, 1840 * ''Janthina striulata'' Carpenter, 1857: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina trochoidea'' Reeve, 1858: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina vinsoni'' Deshayes, 1863: synonym of ''Janthina exigua'' Lamarck, 1816 * ''Janthina violacea'' Röding, 1798: synonym of ''Janthina janthina'' (Linnaeus, 1758) * ''Janthina vulgaris'' Gray, 1847: synonym of ''Janthina janthina'' (Linnaeus, 1758)

==References== {{Reflist}} * Laursen, D. 1953. ''The genus Ianthina: A monograph''. Dana Report 38: 1-40, pl. 1

==External links== {{Commons category|Janthina}} * [https://www.biodiversitylibrary.org/page/16230659 Röding P.F. (1798). Museum Boltenianum sive Catalogus cimeliorum e tribus regnis naturæ quæ olim collegerat Joa. Fried Bolten, M. D. p. d. per XL. annos proto physicus Hamburgensis. Pars secunda continens Conchylia sive Testacea univalvia, bivalvia & multivalvia. Trapp, Hamburg. viii, 199 pp] * [https://www.biodiversitylibrary.org/bibliography/10571 Montfort P. [Denys de]. (1808-1810). Conchyliologie systématique et classification méthodique des coquilles. Paris: Schoell. Vol. 1: pp. lxxxvii + 409 [1808]. Vol. 2: pp. 676 + 16 ] * [https://www.biodiversitylibrary.org/item/175526 Gistel, Johannes [Nepomuk Franz Xaver]. (1848). Naturgeschichte des Tierreichs: für höhere Schulen. [text book]. 1-216, i-xvi, Plates 1-32. Stuttgart. Scheitlin & Krais.] * [https://www.biodiversitylibrary.org/page/15863694 Mörch, O. A. L. (1860). Matériaux pour servir à l'histoire de la famille des Janthines. Journal de Conchyliologie. 8 (3): 261-285] * [https://www.biodiversitylibrary.org/page/52430224#page/61/mode/1up Iredale, T. (1929). Queensland molluscan notes, no. 1. Memoirs of the Queensland Museum. 9(3): 261-297, pls 30-31] * [https://doi.org/10.1080/14772019.2011.607193 Kaim, A.; Tucholke, B. E.; Warén, A. (2012). A new Late Pliocene large provannid gastropod associated with hydrothermal venting at Kane Megamullion, Mid-Atlantic Ridge. Journal of Systematic Palaeontology. 10(3): 423-433] * [https://doi.org/10.3853/j.2201-4349.69.2017.1666 Beu A.G. (2017). Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae). Records of the Australian Museum. 69(3): 119-222] * [http://www.malacolog.org/search.php?mode=findsnail&genus=janthina&associatedname=&author=&year=&yearend=&Search=Search Gary Rosenberg's Malacolog 4.1.1 info on this genus in the Western Atlantic]

Category:Wentletraps Category:Taxa named by Peter Friedrich Röding