''Austropotamobius pallipes'' is an endangered European freshwater

crayfish Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...

, and the only crayfish native to the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

. Its

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s include white-clawed crayfish and Atlantic stream crayfish.

Distribution

It is found from the easterly

Balkan Peninsula The Balkans ( ), also known as the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the whol ...

to Spain and reaches its northerly limit in Great Britain, as well as Ireland (where it is considered introduced), where it is limited to some regions only: its highest

densities Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...

are in chalk streams. ''A. pallipes'' is the only crayfish found in Ireland, occurring over limestone areas in rivers, streams, canals, and lakes. In France, ''A. pallipes'' is found in streams such as the Mornante and Sellon, two small tributaries of the

Dorlay The Dorlay () is a river that flows through the Loire department, France. It is a tributary of the Gier, which in turn is a tributary of the Rhône. The Gier valley was formerly heavily industrialized with coal and iron mines and factories. Ba ...

in the Loire department. It is protected as a heritage species. It has also been introduced to

Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast o ...

, Liechtenstein, and Portugal (from where it is now extirpated). It was once found across most of Great Britain; however its distribution is rapidly shrinking, and it is recorded in Yorkshire,

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

and northern England, east Kent, eastern Wales, the

Candover Brook The Candover Brook is a chalk stream in the English county of Hampshire. It is a tributary of the River Itchen, which it joins near the town of New Alresford. The stream rises from springs just to the south of the village of Preston Candover. ...

that flows into the Itchen in Hampshire; parts of

Essex Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and Gr ...

, and several long headwaters of the River Thames, where it competes with the introduced

noble crayfish ''Astacus astacus'', the European crayfish, noble crayfish, or broad-fingered crayfish, is the most common species of crayfish in Europe, and a traditional food source. Like other true crayfish, ''A. astacus'' is restricted to fresh water, livin ...

, itself also facing competition from the introduced signal crayfish.

Dowdeswell Reservoir Dowdeswell Reservoir and former water treatment works lie below the parish of Dowdeswell in Gloucestershire. They were originally built by Cheltenham Corporation to supply the town of Cheltenham with drinking water (since 1886) and subsequen ...

, Gloucestershire, has the species and during works of 1998,

Severn Trent Severn Trent plc is a water company based in Coventry, England. It supplies 4.6 million households and business across the Midlands and Wales. It is traded on the London Stock Exchange and a constituent of the FTSE 100 Index. Severn Trent, the ...

ensured its protection. Disease from invasive species has wiped it from the naturally alkaline

River Frome, Bristol The Frome , historically the Froom, is a river that rises in Dodington Park, South Gloucestershire, and flows southwesterly through Bristol to join the river Avon. It is approximately long, and the mean flow at Frenchay is . The name ''Frome ...

, 2007–08.

Ecology

It is absent from more acidic waters and occurs in streams with a moderate flow alongside other freshwater invertebrates such as

caddis fly The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

, mayfly, and mollusc species. Trout and three-spined stickleback also occur in the same habitat. Tree roots and rocks in the banks provide shelter. Juveniles shelter in vegetation such as watercress and grass mats growing out of the bank.

Description

''A. pallipes'' is olive-brown, with pale undersides to the

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or Arthrop ...

s (whence its specific Latin epithet ''pallipes'', "pale feet"). It may grow to long and adult sizes below are more common. It typically lives in rivers and streams about 1 m (3 ft) deep, where it hides among rocks and submerged logs, emerging to

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...

for food, and in lakes.

Conservation

Two main reasons for decline are: *

Introduction Introduction, The Introduction, Intro, or The Intro may refer to: General use * Introduction (music), an opening section of a piece of music * Introduction (writing), a beginning section to a book, article or essay which states its purpose and ...

of the invasive North American signal crayfish (''Pacifastacus leniusculus'') and red swamp crayfish (''Procambarus clarkii''): The former is a

carrier Carrier may refer to: Entertainment * ''Carrier'' (album), a 2013 album by The Dodos * ''Carrier'' (board game), a South Pacific World War II board game * ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...

crayfish plague Crayfish plague (''Aphanomyces astaci'') is a water mold that infects crayfish, most notably the European '' Astacus'' which dies within a few weeks of being infected. When experimentally tested, species from Australia, New Guinea and Japan wer ...

, an infectious disease to which it has resistance, while ''A. pallipes'' has none. *Water pollution: Many local extinctions are caused by surface runoff of

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to ...

s and of bleached, insufficiently treated, or illegal untreated wastewater.

References

External links