Cornish Biodiversity Network  -  Supporting Wildlife Recording

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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Janthina janthina - Common Violet Sea-snail

Range & Status

This species, together with the other two following, is holopelagic, drifting at the surface of the sea by a float of mucus with entangled air bubbles. This species is cosmopolitan in distribution, living primarily between latitudes 50\'ba N and 40\'ba S, but liable to be blown by prevailing south-westerly winds, drifting beyond these limits and stranded on southwestern and western coasts of the British Isles. They are most often found with large strandings of Velella velella , Jack Sail-by-the-wind, upon which it preys. Janthina janthina may be stranded anywhere along the western coasts of Britain and Ireland but the great majority of records are from the Cornish coastline. Normally only relatively small numbers are to be found, however, between December 2006 and January 2007 in excess of 900 specimens were recorded on the north Cornish coast.


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.