BIOTIC Species Information for Caecum armoricum
Researched byNicola White Data supplied byMarLIN
Refereed byDennis R. Seaward
Scientific nameCaecum armoricum Common nameDeFolin's lagoon snail
MCS CodeW416 Recent SynonymsCaecum incomptum Monterosata, 1884

PhylumMollusca Subphylum
Superclass ClassGastropoda
SubclassProsobranchia OrderMesogastropoda
Suborder FamilyCaecidae
GenusCaecum Speciesarmoricum

Additional InformationThe taxonomy of the Gastropoda has been recently revised (see Ponder & Lindberg 1997, and Taylor 1996). Ponder & Lindberg (1997) suggest that Mesogastropoda should be included in a monophyletic clade, the Caenogastropoda.
Taxonomy References Howson & Picton, 1997, Barnes, 1994, Aartsen & Hoenselaar, 1984, Seaward, 1989, Ponder, 1990, Ponder & Lindberg, 1997, Taylor, 1996,
General Biology
Growth formCylindrical
Feeding methodSub-surface deposit feeder
Environmental positionInterstitial
Typical food typesvegetable detritus and ?bacterial and diatom film. HabitFree living
BioturbatorNot relevant FlexibilityNone (< 10 degrees)
FragilityRobust SizeVery small(<1cm)
HeightInsufficient information Growth RateInsufficient information
Adult dispersal potentialNot researched DependencyIndependent
General Biology Additional InformationLittle is known of the biology of this species. Early shell form is a spiral disc of about one whorl. Subsequent growth is tangential, slightly curved and tapering. As the shell tube lengthens, the animal's body only occupies the newer part of the shell near the mouth. A septum is laid down closing off the unwanted part of the shell which then breaks off, keeping the shell small, this is repeated throughout the animals life. It is presumably an adaptation to interstitial life.
Biology References Seaward, 1987,
Distribution and Habitat
Distribution in Britain & IrelandOnly recorded living from The Fleet, Dorset. One shell record from Connemara, W. Ireland (J.E. Phorson, per. comm..)
Global distributionShell records from the Black Sea, Mediterranean, Azores, Canary Isles and the Atlantic coast from Gibraltar to the Channel. The only other known live colony is from a site in the south Gibraltar Strait, N. Africa.
Biogeographic rangeNot researched Depth rangeSee additional information
MigratoryNon-migratory / Resident   
Distribution Additional InformationFound in the mid to lower eulittoral within marine percolation. The fleet population occurs at depth within loose shingle of about 2 cm size, where sea water percolates and where soft flocculent silty material is present but leaving plenty space subject to gently flowing water. Molluscan associates are another small prosobranch Onoba aculeus and the bivalve Lasaea adansoni; in the pale variety pallida.

Substratum preferencesGravel / shingle
Physiographic preferencesIsolated saline water (Lagoon)
Biological zoneMid Eulittoral
Lower Eulittoral
Wave exposureVery Sheltered
Tidal stream strength/Water flowVery Weak (negligible)
SalinityVariable (18-40 psu)
Habitat Preferences Additional Information
Distribution References Barnes, 1994, Seaward, 1987, Seaward, 1989, Hoeksema & Segers, 1993,
Reproduction/Life History
Reproductive typeInsufficient information
Developmental mechanismInsufficient information
Reproductive SeasonInsufficient information Reproductive LocationInsufficient information
Reproductive frequencyInsufficient information Regeneration potential No
Life spanInsufficient information Age at reproductive maturityInsufficient information
Generation timeInsufficient information FecundityInsufficient information
Egg/propagule sizeInsufficient information Fertilization typeInsufficient information
Larval/Juvenile dispersal potentialInsufficient information Larval settlement periodInsufficient information
Duration of larval stageInsufficient information   
Reproduction Preferences Additional InformationDispersal potential is likely to be low.
Reproduction References
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