Biodiversity & Conservation

Spotted cowrie - Trivia monacha

Trivia monacha

Image Robert Keen - Trivia monacha at Scapa Flow, Orkneys.
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Distribution map

Trivia monacha recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Trivia monacha is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Mollusca Snails, slugs, mussels, cockles, clams & squid
Class Gastropoda Snails, slugs & sea butterflies
Authority da Costa, 1778
Recent synonyms Trivia europaea (Montagu, 1808).
Map icon Recorded Distribution in Britain and Ireland This species is widely distributed, mainly around the west coast of Britain and Ireland.
Habitat information icon Habitat information Trivia monacha is found on the lower shore and sublittorally on rocky coasts associated with its prey, colonial sea squirts.
Text page icon Description This species has a thickly calcified, glossy shell, with closely spaced transverse ridges. The shell is up to 12 mm long by 8mm wide. The upper surface is reddish-brown in colour with 3 diagnostic spots.The underside of the shell is flattened and white. The head, tentacles, foot and mantle are brightly coloured, from yellow, red, orange and brown, the foot often being paler. When the animal is active the mantle almost completely obscures the shell, and the mantle edge draws out anteriorly into a long siphon. The shell aperture is narrow, running the whole length of the shell, turned left at the ends with both sides ridged.
Identifying features
  • Oval, glossy shell with marked ridges on surface.
  • Shell up to 12 mm x 8 mm.
  • Long , narrow aperture.
  • Upper shell surface is reddish-brown with 3 brown spots.
  • Underside of shell is flattened and white.
  • Mantle wraps around almost entire shell when animal is active.
  • Head, tentacles, foot and mantle brightly coloured from yellow, red, orange and brown.
Additional information icon Additional information Trivia monacha can be confused with Trivia arctica, the former being larger and having 3 distinctive brown spots on its shell. There is no operculum present, and the females have an additional ventral pedal gland. This species feeds on the ascidians Botryllus schlosseri, Botrylloides leachi, and Diplosoma listerianum. Breeding occurs in late spring and summer. The female deposits flask-shaped egg capsules (each containing 800 eggs), in holes that have been eaten out of the ascidian. After a few weeks the larva emerge and are free swimmming for a few months. Juveniles (5 mm long) have a short spire, wide aperture and lack the characteristic ridging of mature adults.

This review can be cited as follows:

Sonia Rowley 2008. Trivia monacha. Spotted cowrie. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 28/11/2015]. Available from: <>