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Mediterranean invasive species factsheet
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Species report Crepidula fornicata, Slipper limpet
AFFILIATION
SCIENTIFIC NAME AND COMMON NAME
Crepidula fornicata
MOLLUSCS
REPORTS
1
Slipper limpet
Key Identifying Features
The slipper limpet is a snail with a smooth, ovalshaped
shell that shows irregular concentric growth lines. It is
white, cream, yellow or pinkish with brown or red veins
or spots. Inside it has a thin lamina extending halfway
across the shell aperture. In the Mediterranean, slipper
limpets can attain sizes of up to 3 cm. They are
commonly found attached one on top of the other
forming stacks of 2–20 animals, with the largest at the
base attached firmly to an object with its muscular foot.
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Identification and Habitat
Other species that look similar
This species is a filter-feeder occurring within sheltered
coastal bays and estuaries, sometimes in low-salinity
environments. It settles on other shells or hard
substrates on mud and sand-gravel bottoms from lowest
water down to depths of about 30 m. It can also survive
prolonged periods out of the water, especially if exposed
to freezing temperatures, and polluted waters where
turbidity is particularly high.
Reproduction
Crepidula fornicata is a hermaphrodite, changing sex
during its life. Females brood eggs that are internally
fertilized by males that stack on top of them. Usually a
few large females are on the bottom and several smaller
males stack on top. Eggs contained in capsules hatch
into planktonic larvae which, after a short larval period,
settle on hard substrates in response to a water-soluble
chemical secreted by adults. They attach to a stack and
reach maturity as young males in about two months,
subsequently undergoing a sex change to become
females. Occasionally solitary (not stackforming)
individuals occur, in which case they selffertilize.
Similar Species
The native species Crepidula moulinsii and Crepidula
unguiformis could be confused with C. fornicata. C.
moulinsii has a more rounded and convex shell shape
that shows a wrinkled surface and light brown stripes
whereas C. unguiformis has a white shell of elongated
shape and flatter surface.
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History and Route of Introduction
Management Options
Originally from the western Atlantic, from the St
Lawrence estuary to northern Mexico, the species was
first observed in Europe on the west coast of Britain in
1872, probably introduced in association with culture
oyster spat, and it then spread along other European
coasts. The slipper limpet may also potentially spread
via boat fouling (in the communities encrusting a ship’s
hull) or attached to floating objects and marine litter. In
the Mediterranean it was first reported in southern
France (Thau Lagoon) in 1982. Since then it has
followed the same path as the Pacific oyster
(Crassostrea gigas), having been reported also in Malta,
Italy and Greece.
Suggested prevention actions to avoid slipper limpet
settlement should include education and public
awareness-raising combined with monitoring, particularly
close to and inside aquaculture farms. Early detection
is possible by monitoring shellfish grounds and mollusc
culture sites in the proximity of MPAs on a periodic
basis.
Oyster spat, juvenile mussels or clams with attached
slipper limpets should be removed. Control action in the
case of this species is feasible as its presence is
sporadic in the Mediterranean.
Further Reading
Ecological Impacts
Its high-density colonies (up to several thousand
individuals per square metre) have major effects on the
macro-benthic fauna and flora, as they compete for food
with other filter-feeding invertebrates and increase
carbon release. Moreover, the production of large
amounts of faeces and pseudo-faeces, increasing the
deposition of mud, can have a considerable impact on
sediment composition and the associated biota (such as
free-living coralline algae).
http://www.ciesm.org/atlas/CrepidulForni.html
http://www.europe-aliens.org/pdf/Crepidula_fornicata.pdf
http://www.nobanis.org/speciesInfo.asp?taxaID=229
Global Invasive Species Database:
http://www.issg.org/database/species/ecology.asp?si=600&fr=1&
An unexpected positive impact is that its feeding
activities may prevent blooms of harmful algae.
Economic Impacts
The slipper limpet can become a pest on commercial
oyster and mussel farms, reducing the productivity of
aquaculture and natural harvesting grounds. Additional
costs are associated with sorting and cleaning shells
fouled by C. fornicata before marketing. It is also known
to foul manmade structures and equipment.
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Map of sightings of the species Crepidula fornicata, Slipper limpet
Legend
Algae
Molluscs
Angiosperm
Crustaceans
Combjellies /
Ctenophores
Fishes
Cnidarians
Ascidians
Centre for Mediterranean
Cooperation
More Information: Guide and reports platform for Marine Protected Areas (MPAs) in the Mediterranean. www.iucn-medmis.org
2013-2015 © IUCN Centre for Mediterranean Cooperation. More info: www.iucn-medmis.org
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MPAs, Country
Posidonies du Cap d'Adge, France
Date
Before 2013
How to cite this tab:
Crepidula fornicata - Invasive Alien Species Fact Sheet for
Mediterranean Network of MPAs. From Online Database
MedMIS (IUCN Center for Mediterranean Cooperation,
Download date 17/06/2017.
More information about this species from: Otero, M., Cebrian,
E., Francour, P., Galil, B., Savini, D. 2013. Monitoring Marine
Invasive Species in Mediterranean Marine Protected Areas
(MPAs): A strategy and practical guide for managers. Malaga,
Spain: IUCN. 136 pages
www.iucn.org/dbtw-wpd/edocs/2013-008-Es.pdf .
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