Caecum armoricum

Researched By	Nicola White	Data Supplied By	MarLIN
Refereed by	Dennis R. Seaward
Taxonomy
Scientific name	Caecum armoricum	Common name	DeFolin's lagoon snail
MCS Code	W416	Recent Synonyms	Caecum incomptum Monterosata, 1884
Phylum	Mollusca	Subphylum
Superclass		Class	Gastropoda
Subclass	Prosobranchia	Order	Mesogastropoda
Suborder		Family	Caecidae
Genus	Caecum	Species	armoricum
Subspecies
Additional Information	The 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 form	Cylindrical	Feeding method	Sub-surface deposit feeder
Mobility/Movement	Crawler	Environmental position	Interstitial
Typical food types	vegetable detritus and ?bacterial and diatom film.	Habit	Free living
Bioturbator	Not relevant	Flexibility	None (< 10 degrees)
Fragility	Robust	Size	Very small(<1cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	Not researched	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
Additional Information	Little 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 & Ireland	Only recorded living from The Fleet, Dorset. One shell record from Connemara, W. Ireland (J.E. Phorson, per. comm..)
Global distribution	Shell 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 range	Not researched	Depth range	See additional information
Migratory	Non-migratory / Resident
Distribution Additional Information	Found 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 preferences	Gravel / shingle	Physiographic preferences	Isolated saline water (Lagoon)
Biological zone	Mid Eulittoral, Lower Eulittoral	Wave exposure	Very Sheltered
Tidal stream strength/Water flow	Very Weak (negligible)	Salinity	Variable (18-40 psu)
Habitat Additional Information
Distribution References	Barnes, 1994, Seaward, 1987, Seaward, 1989, Hoeksema & Segers, 1993
Reproduction/Life History
Reproductive type	Insufficient information	Developmental mechanism	Insufficient information
Reproductive Season	Insufficient information	Reproductive Location	Insufficient information
Reproductive frequency	Insufficient information	Regeneration potential	No
Life span	Insufficient information	Age at reproductive maturity	Insufficient information
Generation time	Insufficient information	Fecundity	Insufficient information
Egg/propagule size	Insufficient information	Fertilization type	Insufficient information
Larvae/Juveniles Larval/Juvenile dispersal potential Insufficient information Larval settlement period Insufficient information Duration of larval stage Insufficient information
Additional Information	Dispersal potential is likely to be low.
Reproduction References