The shelled slug, Testacella haliotidea, is a rarely seen, air-breathing, carnivorous land slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

, a terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 gastropod mollusk in the family Testacellidae, the shelled slugs.

Description

This slug, like others in the family, has a small shell which is situated towards the rear of the animal. The species is called haliotidea because the shell of this species resembles in shape a miniature version of the shell of the marine species in the family Haliotidae, the abalones.

This is a large, very agile, pale brown slug, with a length of 12 cm. It has a small ear-shaped, external shell, less than 1 cm long, at the tail end of the mantle

Mantle (mollusc)

The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...

.
The following shell description is modified from Tryon 1885. The shell is oval-auriform, depressed, and rugosely striate. It has a thin, readily deciduous epidermis. The apex is minute, very short and not separated from the columellar margin. The aperture is rounded and usually dilated anteriorly; the columella and the outer margin of the aperture form a distinct angle at their junction. The interior of the shell is whitish and pearly. The length of the shell is 6-10 mm.

Distribution

This species is common along the western Mediterranean, along the European Atlantic coast and throughout Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 apart from northern Scotland

Scotland

Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

. This slug occurs in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 but its distribution is under-recorded there.

It also occurs as an introduced species in southern Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and 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...

 (where it is called the earshell slug). The distribution data for the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, (Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, Wisconsin

Wisconsin

Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...

) and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 (British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, Nova Scotia

Nova Scotia

Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

) are incomplete.

Habitat

This species is seen mostly in the spring, living in cultivated habitats or on disturbed ground. The slug lives mostly underground, but may sometimes be found under stones or in leaf litter.

Life habits

This slug hunts and eats earthworms underground. The radula teeth are a functional adaption in the capturing of prey.