Common slipper shell
Encyclopedia
The common slipper shell, Crepidula fornicata, has many other common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

s including common Atlantic slippersnail, boat shell, quarterdeck shell, fornicating slipper snail, and it is known in Britain as the "common slipper limpet
Limpet
Limpet is a common name for a number of different kinds of saltwater and freshwater snails ; it is applied to those snails that have a simple shell which is more or less conical in shape, and either is not spirally coiled, or appears not to be coiled in the adult snails.The name limpet is most...

". This is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of medium-sized sea snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusc in the family Calyptraeidae
Calyptraeidae
Calyptraeidae, common name the slipper snails or slipper limpets, cup-and-saucer snails, and Chinese hat snails are a family of small to medium-sized marine prosobranch gastropods...

, the slipper snails and cup and saucer snails.

Description

The size of the shell is 20-50 mm. The maximum recorded shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...

 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.

Distribution

The species is native to the western Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, specifically the Eastern coast of North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. 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.

Nonindigenous distribution

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
Ostend
Ostend  is a Belgian city and municipality located in the Flemish province of West Flanders. It comprises the boroughs of Mariakerke , Stene and Zandvoorde, and the city of Ostend proper – the largest on the Belgian coast....

 and since the 1930’s, it is seen as a common species along Belgian coast.

The species is considered an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 in Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, the Netherlands, Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, and the UK, and has also spread to Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 and Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. It is known to damage oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....

 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
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...

 and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

.

Habitat

This 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
Seashell
A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer created by an animal that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by beachcombers...

 and on dock pilings.

Feeding habits

Generally for Calyptraeidae, feeding habits include planktonic and minute detrital food items through either suspension or deposit feeding.

Life cycle

The species is a sequential hermaphrodite. The largest and oldest animals, at the base of a pile are female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...

, the younger and smaller animals at the top are male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...

. If the females in the stack die, the largest of the males will become a female.

External links

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