Defolin's lagoon snail

Caecum armoricum

 

This tiny creature, measuring only 2mm long, looks nothing like the more familiar sea snails.  Defolin’s lagoon snail has neither a spiral shell (typical of, for example, whelks) or a domed limpet-like shell, but is instead shaped like a slightly curved test-tube.

A very rare creature, Defolin’s lagoon snail is found only in the Fleet, in Dorset.  It lives between small pebbles high on the beach, where seawater seeps through the shingle to form lagoons.

As it is found only in this single location, Defolin’s lagoon snail is very vulnerable.  Any changes to the lagoons in which it lives could result in the complete disappearance of the lagoon snails.

Coastal lagoons are often transient, and may disappear through natural beach movement.  Human actions, such as the construction of coastal defences, can cause beaches to shrink or grow, and so can speed up the loss of coastal lagoons.

 

Until recently this snail was only known to occur in the UK at the Fleet in Dorset. Recently, it has been discovered at a further two locations, in the saline lagoons at the seaward end of Lydd Ranges and at Pagham Harbour. Outside the UK, live colonies have been found at a site on the coast of north Africa in the South Gibraltar Strait. Shell records have been found in Ireland, the Atlantic coast from Gibraltar to the Channel, the Black Sea, and Mediterranean.

 

European distribution

Live colonies have been found only in the Fleet, Dorset and at a site on the coast of north Africa in the South Gibraltar Strait.  Shell records have been found in Ireland, the Atlantic coast from Gibraltar to the Channel, the Black Sea, and Mediterranean.

 

Conservation status/need

  • Defolin's Lagoon Snail FactNationally rare marine animal
  • Protected under Schedule 5 of the Wildlife and Countryside Act 1981
  • The coastal lagoons in which Defolin's lagoon snails are found are a UKBAP priority habitat and are listed on Annex I of the Habitats Directive

 

Further information

Marine Life Information Network