Violet snail (Janthina janthina)
Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
Researched by | Sonia Rowley | Refereed by | Admin |
Authority | (Linnaeus, 1758) | ||
Other common names | - | Synonyms | - |
Summary
Description
The head of the violet snail has a long cylindrical snout with a terminal mouth. The tentacles are forked, have no eyes and project half way along its side's. The foot has a broad anterior and tapers to a posterior point. There is a broad depression or funnel at the anterior part of the sole, where the float is secreted. The posterior of the sole has longitudinal grooves. The flesh of this species is deep violet or black and in adults the operculum is absent.
Recorded distribution in Britain and Ireland
Janthina janthina has a circumequatorial distribution and has been recorded from strandings after storms along the coasts of SW Ireland, SW Wales, SW England and as far east as the Isle of Wight.Global distribution
-Habitat
Janthina janthina is a holopelagic species, drifting on the ocean surface. It floats uniquely by a raft of bubbles bound by mucus secreted from the foot, and preys on the pelagic coelenterates Velella velella and Porpita sp. The shells of this species can occasionally be found on the strandline particularly after prolonged south-westerly gales (Hayward & Ryland, 1995).Depth range
-Identifying features
- Up to 4 cm high; 3 cm broad.
- Globular fragile, thin shell.
- Shell dark purple.
- Short spire of 6 whorls (protoconch).
- Deep violet or black flesh.
- Floats on ocean surface via a raft of bubbles and mucus.
Additional information
Janithina janthina is the commonest member of the Janthinidae family. This species is ovoviparous where the eggs develop within the females genital tract and later shed as veliger larvae from the left side of the mantle cavity (Graham, 1988). The males are aphallic (no penis) and produce spermatozeugmata that swim to the female and enter the genital tract. Therefore fertilization occurs before the eggs have left the ovary, suggesting the species is a protandrous consecutive hermaphrodite.Listed by
- none -
Bibliography
Graham, A., 1988. Molluscs: prosobranchs and pyramellid gastropods (2nd ed.). Leiden: E.J. Brill/Dr W. Backhuys. [Synopses of the British Fauna No. 2]
Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.
Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.
Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]
Moore, J. 2002. Porcupine Marine Natural History Society Newsletter. Porcupine Marine Natural History Society Newsletter, 11, pp13-14.
Datasets
Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: https://doi.org/10.15468/4bsawx accessed via GBIF.org on 2018-09-25.
Conchological Society of Great Britain & Ireland, 2023. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2024-09-27.
Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01
NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.
OBIS (Ocean Biodiversity Information System), 2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-10-03
Outer Hebrides Biological Recording, 2018. Invertebrates (except insects), Outer Hebrides. Occurrence dataset: https://doi.org/10.15468/hpavud accessed via GBIF.org on 2018-10-01.
Citation
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Last Updated: 26/06/2007