AppearanceThe size of the shell is 20-50 mm. The maximum recorded shell length is 56 mm.
This sea snail has an arched, rounded shell. On the inside of the shell there is a white "deck" which causes the shell to resemble a boat or a slipper, hence the common names.
Some of these may be flat, slightly arched, or arched heavily. The 'Flat slipper shell' is also another type of slipper shell.
DistributionThe species is native to the western Atlantic Ocean, specifically the Eastern coast of North America. It has been introduced accidentally to other parts of the world and has become problematic.
Distribution of ''Crepidula fornicata'' ranges from 48°N to 25°N; 97.2°W to 25°W from as far north as Nova Scotia to as far south as the Gulf of Mexico.It was introduced to the state of Washington.
The species was however brought to Europe together with the eastern oyster ''Crassostrea virginica''. In Belgium, the first slipper limpet was found on 28 September 1911 attached to an oyster in Ostend and since the 1930’s, it is seen as a common species along Belgian coast.
The species is considered an invasive species in Denmark, France, Italy, the Netherlands, Spain, and the UK, and has also spread to Norway and Sweden. It is known to damage oyster fisheries. The slipper limpet has little to no predators in Europe, and can thrive on several types of hard bottoms and shellfish banks. A continued expansion to the north is probably inhibited by temperature: low temperatures during the winter can slow down or inhibit the development of the slipper limpet.
It has also been introduced to the Pacific Northwest and Japan.
BehaviorThe species is a sequential hermaphrodite. The largest and oldest animals, at the base of a pile are female, the younger and smaller animals at the top are male. If the females in the stack die, the largest of the males will become a female.
HabitatThis is a common snail, usually found intertidally, infralittoral and circalittoral and in estuaries.
Minimum recorded depth is 0 m. Maximum recorded depth is 70 m.
They are often found, sometimes living stacked on top of one another, rocks, on horseshoe crabs, shells and on dock pilings.
FoodGenerally for Calyptraeidae, feeding habits include planktonic and minute detrital food items through either suspension or deposit feeding.
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