Astacus astacus, the European crayfish, noble crayfish or broad-fingered crayfish, is the most common 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 crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 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...

, and a traditional foodstuff. Like other crayfish, Astacus astacus is restricted to fresh water

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

, living only in unpolluted

Pollution

Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

 streams, rivers and lakes. It is found from 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...

 throughout Central Europe

Central Europe

Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...

, to the Balkan peninsula

Balkans

The Balkans is a geopolitical and cultural region of southeastern Europe...

, and north as far as parts of the British Isles

British Isles

The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...

, Scandinavia

Scandinavia

Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

, and the western parts of the former Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

. Males may grow up to 16 cm long, and females up to 12 cm.

Ecology

A. astacus is nocturnal

Nocturnal animal

Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

 and feeds on worm

Worm

The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

s, aquatic insects

Aquatic insects

Aquatic insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.-Breathing:...

, molluscs and plants, spending the day resting in a burrow

Burrow

A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...

. They become sexually mature

Sexual maturity

Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...

 after three to four years and a series of moults

Ecdysis

Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...

, and breed in October and November. Fertilised

Fertilisation

Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...

 eggs are carried by the female, attached to her pleopods, until the following May, when they hatch and disperse. The main predators of A. astacus, both as juveniles and adults, are mink

Mink

There are two living species referred to as "mink": the European Mink and the American Mink. The extinct Sea Mink is related to the American Mink, but was much larger. All three species are dark-colored, semi-aquatic, carnivorous mammals of the family Mustelidae, which also includes the weasels and...

, eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s, perch

Perch

Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the...

, pike

Northern Pike

The northern pike , is a species of carnivorous fish of the genus Esox...

, otter

Otter

The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....

s, and muskrat

Muskrat

The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...

s.

Consumption

Astacus astacus was once abundant in Europe, although it was expensive to buy, and is considered to be the finest edible crayfish. It is, however, susceptible to the crayfish plague

Crayfish plague

Crayfish plague, Aphanomyces astaci, is a water mould that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected...

 carried by the invasive American

United States

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

 species signal crayfish

Signal crayfish

The signal crayfish, Pacifastacus leniusculus, is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the Scandinavian Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease...

 (Pacifastacus leniusculus), and is therefore listed as a vulnerable species

Vulnerable species

On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

 on the IUCN Red List

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

.

Documentation of the consumption of A. astacus dates back to the Middle Ages

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

, when it was popular among the Swedish nobility

Swedish nobility

The Swedish nobility were historically a legally and/or socially privileged class in Sweden, part of the so-called frälse . Today, the nobility is still very much a part of Swedish society but they do not maintain many of their former privileges...

, spreading to all social class

Social class

Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...

es by the 17th and 18th centuries due to its ready availability. The crayfish are collected from the wild in traps, a practice which is being replaced by more intensive aquaculture

Aquaculture

Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 of the signal crayfish in man-made ponds. The consumption of crayfish is an important part of traditional Scandinavian culture, including the crayfish party

Crayfish party

A crayfish party is a traditional summertime eating and drinking celebration in the Nordic countries. The tradition originated in Sweden, where a crayfish party is called a kräftskiva...

 or , a feast to mark the end of summer.

Astacin

Astacin

Astacin

In molecular biology, astacin is a family of metallopeptidases. These metallopeptidases belong to the MEROPS peptidase family M12, subfamily M12A...

s are a family of digestive enzyme

Digestive enzyme

'Digestive enzymes' are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. Digestive enzymes are found in the digestive tract of animals where they aid in the digestion of food as well as inside the cells,...

s, discovered in the 1990s, which were first isolated from Astacus astacus. More than 20 enzymes of this group have since been discovered in animals from Hydra

Hydra (genus)

Hydra is a genus of simple fresh-water animal possessing radial symmetry. Hydras are predatory animals belonging to the phylum Cnidaria and the class Hydrozoa. They can be found in most unpolluted fresh-water ponds, lakes, and streams in the temperate and tropical regions and can be found by...

to human

Human

Humans are the only living species in the Homo genus...

s.