information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

A bivalve mollusc (Lasaea adansoni)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



A small, oval, plump inequilateral shell, 1 - 3.2 mm in length, with slightly posterior beaks and a smooth margin. The shell is dirty white in colour, often with a pinkish red tinge. High shore specimens may appear dark red in colour. The shell has a fine sculpture of concentric lines and the larval shell (prodissoconch) is visible and large, forming blunt, rounded umbones. May be confused with Turtonia minuta, which occupies a similar habitat.

Recorded distribution in Britain and Ireland

Found on all rocky coasts of Britain, except the south east, presumably due to a lack of suitable habitat. Also found amongst mussels on sedimentary shores and recorded from the shingle beaches of the Fleet, Dorset. Probably under recorded.

Global distribution

It is widely distributed in north-west Europe. Lasaea adansoni (as rubra) has been recorded in the Kerguelan Islands, South Antarctic, and the variant Lasaea rubra himenoa is found in New Zealand.


Lasaea adansoni is a crevice or interstitial dwelling bivalve. It is found in high numbers in intertidal crevices. It also occupies interstices between mussels and barnacle shells, in the holdfasts of macroalgae (e.g. Fucus spp.), in the fronds of small algae and especially amongst tufts of the lichen Lichina pygmaea. It is most abundant in the upper and mid-shore, decreasing in numbers near high and low water.

Depth range


Identifying features

  • Left valve with one cardinal tooth but none on the right valve.
  • Beaks slightly posterior.
  • Umbones rounded with a large prodissoconch.

Additional information

The genus Lasaea is cosmopolitan in distribution and composed of numerous species, which may be local variations of Lasaea adansoni (= rubra). Gosling (1994) suggested that species within this genus should be referred to as Lasaea rubra complex.

Listed by

- none -

Further information sources

Search on:


  1. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

  2. Gosling, E.M., 1994. Speciation and wide-scale genetic differentiation. In Genetics and evolution of aquatic organisms, (ed. A.R. Beaumont), pp.1-15. London: Chapman & Hall.

  3. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

  4. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  5. 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.]


This review can be cited as:

Tyler-Walters, H., 2005. Lasaea adansoni A bivalve mollusc. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 15-08-2018]. Available from:

Last Updated: 17/10/2005