Taxon profile


Common Atlantic Slippersnail
Crepidula fornicata (Linnaeus, 1758)

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  order Littorinimorpha »  family Calyptraeidae - Slipper Shells »  genus Crepidula

Other names

= American Slipper Limpet
= Slipper Limpet


Crepidula fornicata - Common Atlantic Slippersnail

Author: Karla Otta

Crepidula fornicata - Common Atlantic Slippersnail

Author: Jan Delsing

Crepidula fornicata - Common Atlantic Slippersnail

Author: Graham, A.

Taxon in country check-lists*

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Common Atlantic Slippersnail
Distribution: Canada to Florida, Texas. Size: 18 to 50 mm
Description: Color of alternating white and brown irregularly shaped rays usually with a broad white ray toward the middle, interior tan to purple, septum (deck) with a brown ring around a white deck; shape varies, round to ovate; sculpture smooth, except for fine growth lines; body whorl primary component of shell; deck covers more than half of aperture with left side longer than right; concave, shallow, muscle scar absent; apex blunt, twisted right, adherent to margin of shell; aperture oblong, oval with a thin margin.
Habitat: Typically a littoral species with individuals growing on one another. Depth range 0 to 70 m (230 ft).
Remarks: Because of the variability of this species, it is surprising there are not more synonyms. See Ode and Speers (1969d); Andrews (1977); Hoagland (1977); Ode (1983a).
Tunnell, J.W. , Andrews, J. , Barrera, N.C. & Moretzsohn, F., 2010. Encyclopedia of Texas seashells.
Diagnostic characters
Animals usually adhering to one another to form chains or stacks. Individual shell with small depressed spire and large last whorl. Aperture large, kidney-shaped, half blocked (in empty shell) by large partition near spire. Animal with neck lobes as in Calyptraea. Operculum absent.

Other characters
There are only two whorls, one of which forms the protoconch the other the rest of the shell, which is solid and rather glossy, and without ornament apart from occasional growth lines. Yellow or red-brown, mottled with short dark streaks; there is usually a paler band along the periphery. The internal septum is chalk-white, with dark chestnut along its attachment; the rest of the internal surface is tan. Up to 50 mm long, 25 mm high.
The animal shows the same general organization as Calyptraea, though the mantle cavity has become much deeper and the gill longer; the penis of the male stage is not bilobed and it disappears when the animal becomes female. The flesh is yellowish, with dark pigment on the snout, tentacles, mantle edge and penis.
C. fornicata lives in chains of up to fifteen animals, usually fewer. The smaller animals at one end are male, some in the middle are changing sex, and the large animals at the opposite end are female; the males fertilize females in the same chain. Chains persist by the addition of small males at one end while females die at the other. The animals are ciliary feeders (Orton, 1912). They are normally sublittoral, living to depths of 10 m, but are often thrown on to beaches after storms. The species is centred on the Atlantic coast of North America but animals were introduced, with imported oysters, to Essex in 1887-90 and have now spread along the south coast of England; they have also been found in the Bristol Channel and been reported from Northumberland, Belfast Lough and Kerry, though it is doubtful whether they can form established populations in all these places. In Europe the species has spread from an original Dutch importation to the Kattegat and Skagerrak, and to the French Atlantic coast. C. fornicata often occurs in enormous numbers and is a serious pest of oyster beds (Orton, 1909; Chipperfield, 1951; Walne, 1956).
Eggs are brooded under the foot of the female; from the capsules hatch free-swimming veliger larvae which are attracted at metamorphosis to existing chains on which they settle and become small males; should they fail to find a chain on which to settle they rapidly become female and so attractive to other settling larvae, and thus the founder matriarch of a new stack. The sexual biology of this species has been discussed by Gould (1952), Coe (1953) and Hoagland(1978).
Vernacular name: slipper limpet.
Graham, A.; 1988. Molluscs: Prosobranch and Pyramidellid Gastropods.
Author: Jan Delsing

Links and literature

EN Galli C.: WMSDB - Wolrdwide Mollusc Species Data Base July 10, 2013 [] [as Crepidula fornicata Linnaeus, 1758]
Data retrieved on: 23 November 2013
CZ Pfleger V. (1999): České názvy živočichů III. Měkkýši (Mollusca), Národní muzeum, (zoologické odd.), Praha, 108 pp. [as Crepidula fornicata (LINNÉ, 1758)]
Data retrieved on: 11 November 2013
IT Repetto G., Orlando F. & Arduino G. (2005): Conchiglie del Mediterraneo, Amici del Museo "Federico Eusebio", Alba, Italy [as Crepidula fornicata (Linné, 1758)]
EN Dan Minchin (2007): Rapid coastal survey for targeted alien species associated with floating pontoons in Ireland, Aquatic invasions, Volume 2, Issue 1: 63-70 [as Crepidula fornicata Linnaeus, 1758]
EN Stephan Gollasch and Stefan Nehring (2006): National checklist for aquatic alien species in Germany, Aquatic invasions, Volume 1, Issue 4: 245-269 [as Crepidula fornicata (Linnaeus, 1758)]

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