Crayfish

Crayfish

Overview
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater
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...

 crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s resembling small lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...

s, to which they are related. They breathe through feather-like gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s and are found in bodies of water that do not freeze to the bottom; they are also mostly found in brooks and streams where there is fresh water running, and which have shelter against predators. Most crayfish cannot tolerate polluted water
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

, although some species such as the invasive
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....

 Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

 are more hardy.
Discussion
Ask a question about 'Crayfish'
Start a new discussion about 'Crayfish'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Recent Discussions
Encyclopedia
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater
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...

 crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s resembling small lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...

s, to which they are related. They breathe through feather-like gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s and are found in bodies of water that do not freeze to the bottom; they are also mostly found in brooks and streams where there is fresh water running, and which have shelter against predators. Most crayfish cannot tolerate polluted water
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....

, although some species such as the invasive
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....

 Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

 are more hardy. Crayfish feed on living and dead animals and plants.

In 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 South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, the term crayfish or cray generally refers to a saltwater spiny lobster
Spiny lobster
Spiny lobsters, also known as langouste or rock lobsters, are a family of about 45 species of achelate crustaceans, in the Decapoda Reptantia...

, of the genus Jasus
Jasus
Jasus is a genus of spiny lobsters which live in the oceans of the Southern Hemisphere. They have two distinct "horns" projecting from the front of the carapace, but lack the stridulating organs present in almost all other genera of spiny lobsters...

 that is indigenous to much of southern Oceania
Oceania
Oceania is a region centered on the islands of the tropical Pacific Ocean. Conceptions of what constitutes Oceania range from the coral atolls and volcanic islands of the South Pacific to the entire insular region between Asia and the Americas, including Australasia and the Malay Archipelago...

, while the freshwater
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...

 species are usually called yabby
Common yabby
The common yabby, Cherax destructor, is an Australian freshwater crustacean in the Parastacidae family. It is listed as a vulnerable species of crayfish by the World Conservation Union , though the validity of this listing is questionable; wild yabby populations remain strong, and have expanded...

 or koura
Paranephrops
Paranephrops is a genus of freshwater crayfish species endemic to New Zealand. They are known as ' in New Zealand, derived from the Māori language...

, from the indigenous Australian and Māori
Maori language
Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...

 names for the animal respectively, or by other names specific to each species. An exception is the freshwater Murray crayfish
Murray crayfish
The Murray crayfish, Euastacus armatus, is a species of freshwater crayfish endemic to Australia that belongs to the family Parastacidae. The Murray crayfish has the largest geographic range of any of the Euastacus crayfish in Australia, being found in the Murray and Murrumbidgee Rivers as well as...

, which belongs to the family Parastacidae
Parastacidae
Parastacidae is the family of freshwater crayfish found in the southern hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand and New Guinea, and extinct taxa also in Antarctica.Three genera are to be found in Chile,...

 and is found on Australia's Murray River
Murray River
The Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...

.

The study of crayfish is called astacology.

Names


The name "crayfish" comes from the Old French word (Modern French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 ). The word has been modified to "crayfish" by association with "fish" (folk etymology). The largely American
American English
American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....

 variant "crawfish" is similarly derived.

Some kinds of crayfish are known locally as lobster
Lobster
Clawed lobsters comprise a family of large marine crustaceans. Highly prized as seafood, lobsters are economically important, and are often one of the most profitable commodities in coastal areas they populate.Though several groups of crustaceans are known as lobsters, the clawed lobsters are most...

s, crawdads, mudbugs, and yabbies
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...

. In the Eastern United States
Eastern United States
The Eastern United States, the American East, or simply the East is traditionally defined as the states east of the Mississippi River. The first two tiers of states west of the Mississippi have traditionally been considered part of the West, but can be included in the East today; usually in...

, "crayfish" is more common in the north, while "crawdad" is heard more in central and western regions, and "crawfish" further south, although there are considerable overlaps.

Anatomy




The body of a decapod
Decapoda
The decapods or Decapoda are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp. Most decapods are scavengers. It is estimated that the order contains nearly 15,000 species in around 2,700 genera, with...

 crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

, such as a crab, lobster, or prawn, is made up of twenty body segments grouped into two main body parts, the cephalothorax
Cephalothorax
The cephalothorax is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. The word cephalothorax is derived from the Greek words for head and thorax...

 and the abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

. Each segment may possess one pair of appendage
Appendage
In invertebrate biology, an appendage is an external body part, or natural prolongation, that protrudes from an organism's body . It is a general term that covers any of the homologous body parts that may extend from a body segment...

s, although in various groups these may be reduced or missing. On average, crayfish grow to 17.5 centimetres (6.9 in) in length, but some grow larger.

Geographical distribution and classification





There are three families of crayfish, two in the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...

 and one in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

. The Southern-Hemisphere (Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

-distributed) family Parastacidae
Parastacidae
Parastacidae is the family of freshwater crayfish found in the southern hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand and New Guinea, and extinct taxa also in Antarctica.Three genera are to be found in Chile,...

 lives in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

 and Australasia
Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...

, and is distinguished by the lack of the first pair of pleopods. Of the other two families, members of the Astacidae
Astacidae
The family Astacidae comprises the freshwater crayfish native to Europe and western North America. It is made up of three genera. Pacifastacus is found on the Pacific coast of the United States and British Columbia and includes the signal crayfish and the Shasta crayfish...

 live in western Eurasia
Eurasia
Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 and western 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...

 and members of the family Cambaridae
Cambaridae
Cambaridae is the largest of the three families of freshwater crayfish, with over 400 species. Most of the species in the family are native to North America east of the Great Divide, such as the invasive species Procambarus clarkii and Orconectes rusticus, with fewer species living in East Asia and...

 live in eastern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and eastern 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...

.

Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

 has an endemic genus, Astacoides
Astacoides
Astacoides is a genus of freshwater crayfish endemic to Madagascar. The first specimens were brought to Europe in 1839, and seven species are now recognised, most of which are on the IUCN Red List. They are large and slow-growing, and are threatened by habitat loss and overexploitation by local...

, containing seven species.

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...

 is home to seven species of crayfish in the genera Astacus
Astacus
Astacus is a genus of crayfish found in Europe and western Asia, comprising three extant and four extinct species....

 and Austropotamobius
Austropotamobius
Austropotamobius is a genus of crayfish in the family Astacidae. It contains three extant species, and one species known from fossils of Barremian age:*Austropotamobius llopisi †*Austropotamobius italicus...

.

Cambaroides
Cambaroides
Cambaroides is a genus of freshwater crayfish. It contains seven species:*Cambaroides dauricus*Cambaroides japonicus*Cambaroides koshewnikowi*Cambaroides sachalinensis*Cambaroides schrenckii*Cambaroides similis...

 is native to 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...

 and eastern mainland Asia.

North America


The greatest diversity of crayfish species is found in southeastern 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...

, with over 330 species in nine genera, all in the family Cambaridae
Cambaridae
Cambaridae is the largest of the three families of freshwater crayfish, with over 400 species. Most of the species in the family are native to North America east of the Great Divide, such as the invasive species Procambarus clarkii and Orconectes rusticus, with fewer species living in East Asia and...

. A further genus of astacid
Astacidae
The family Astacidae comprises the freshwater crayfish native to Europe and western North America. It is made up of three genera. Pacifastacus is found on the Pacific coast of the United States and British Columbia and includes the signal crayfish and the Shasta crayfish...

 crayfish is found in 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 the headwaters of some rivers east of the Continental Divide
Continental Divide
The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...

. Many crayfish are also found in lowland areas where the water is abundant in calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

, and oxygen rises from underground springs.

Crayfish were introduced purposely into a few Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

 reservoirs and other bodies of water decades ago, primarily as a food source for sport fish. They have since dispersed beyond those original sites.

Australasia


Australasia
Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...

 has over 100 species in a dozen genera. Many of the better-known 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...

n crayfish are of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Cherax, and include the marron
Marron
Marron is a name given to two closely related species of crayfish in Western Australia. Formerly considered a single species, it is now thought to comprise two species, the critically endangered Cherax tenuimanus, and the species which is outcompeting it, Cherax cainii.Marron make excellent eating,...

 (now believed to be two species, Cherax tenuimanus
Cherax tenuimanus
Cherax tenuimanus, known as the hairy marron or Margaret River marron, is one of two species of crayfish in Southwestern Australia known as marron. It occupies a narrow range within the southwestern biogeographical region of Margaret River...

 and C. cainii
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...

), red-claw crayfish (Cherax quadricarinatus), yabby (Cherax destructor) and western yabby (Cherax preissii). The marron
Marron
Marron is a name given to two closely related species of crayfish in Western Australia. Formerly considered a single species, it is now thought to comprise two species, the critically endangered Cherax tenuimanus, and the species which is outcompeting it, Cherax cainii.Marron make excellent eating,...

 are some of the largest crayfish in the world. They grow up to several pounds in size. C. tenuimanus
Cherax tenuimanus
Cherax tenuimanus, known as the hairy marron or Margaret River marron, is one of two species of crayfish in Southwestern Australia known as marron. It occupies a narrow range within the southwestern biogeographical region of Margaret River...

 is critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...

, while other large Australasian crayfish are threatened or endangered.

Australia is home to the world's two largest freshwater crayfish – the Tasmanian giant freshwater crayfish
Tasmanian giant freshwater crayfish
The Tasmanian giant freshwater crayfish is the largest freshwater invertebrate in the world. The species is only found in Tasmania , and is listed as a vulnerable species due to habitat loss and over fishing. It is also severely threatened by siltation and de-snagging of streams as decaying wood...

 Astacopsis gouldi, which can achieve a mass of up to 5 kilograms (11 lb) and is found in the rivers of northern Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

, and the Murray crayfish
Murray crayfish
The Murray crayfish, Euastacus armatus, is a species of freshwater crayfish endemic to Australia that belongs to the family Parastacidae. The Murray crayfish has the largest geographic range of any of the Euastacus crayfish in Australia, being found in the Murray and Murrumbidgee Rivers as well as...

 Euastacus armatus, which can reach 2 kilograms (4.4 lb) and is found in much of the southern Murray-Darling basin
Murray-Darling Basin
The Murray-Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River. It drains one-seventh of the Australian land mass, and is currently by far the most significant agricultural...

.

Fossil record


Fossil records of crayfish older than 30 million years are rare, but fossilised 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...

s have been found from strata as old as the late Palaeozoic or early Mesozoic. The oldest records of the Parastacidae
Parastacidae
Parastacidae is the family of freshwater crayfish found in the southern hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand and New Guinea, and extinct taxa also in Antarctica.Three genera are to be found in Chile,...

 are in Australia, and are 115 million years old.

Crayfish plague



Some crayfish suffer from a disease called 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...

. This is caused by the water mould
Water mould
Oömycota or oömycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms . They are filamentous, microscopic, absorptive organisms that reproduce both sexually and asexually...

 Aphanomyces astaci. Species of the genus Astacus
Astacus
Astacus is a genus of crayfish found in Europe and western Asia, comprising three extant and four extinct species....

 are particularly susceptible to infection, allowing the more resistant 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...

 to invade parts of 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...

. Crayfish plague is not indigenous to Europe, rather it was brought there when North American species of crayfish were introduced.

Bait


Crayfish are commonly sold and used as bait, either live or with only the tail meat, and are good at attracting channel catfish
Channel catfish
Channel catfish, Ictalurus punctatus, is North America's most numerous catfish species. It is the official fish of Missouri, Iowa, Nebraska, Kansas, and Tennessee, and is informally referred to as a "channel cat". In the United States they are the most fished catfish species with approximately 8...

, largemouth bass
Largemouth bass
The largemouth bass is a species of black bass in the sunfish family native to North America . It is also known as widemouth bass, bigmouth, black bass, bucketmouth, Potter's fish, Florida bass, Florida largemouth, green bass, green trout, linesides, Oswego bass, southern largemouth...

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

 and muskellunge
Muskellunge
A muskellunge , also known as a muskelunge, muscallonge, milliganong, or maskinonge , is a large, relatively uncommon freshwater fish of North America. Muskellunge are the largest member of the pike family, Esocidae...

. Sometimes the claws are removed so that the crayfish don't stop fish from biting the hook. Crayfish also easily fall off the hook, so casting should be slow.

The result of using crayfish as bait has led to various ecological problems at times. According to a report prepared by Illinois State University
Illinois State University
Illinois State University , founded in 1857, is the oldest public university in Illinois; it is located in the town of Normal. ISU is considered a "national university" that grants a variety of doctoral degrees and strongly emphasizes research; it is also recognized as one of the top ten largest...

, on the Fox River
Fox River (Illinois River tributary)
The Fox River is a tributary of the Illinois River in the states of Wisconsin and Illinois in the United States. There are two other "Fox Rivers" in southern Illinois: the Fox River and a smaller "Fox River" that joins the Wabash River near New Harmony, Indiana.-Wisconsin:The Fox River rises near...

 and Des Plaines River
Des Plaines River
The Des Plaines River is a river that flows southward for through southern Wisconsin and northern Illinois in the U.S. Midwest, eventually meeting the Kankakee River west of Channahon to form the Illinois River, a tributary of the Mississippi River....

 watershed, "The rusty crayfish (used as bait) has been dumped into the water and its survivors outcompete the native clearwater crayfish". This situation has been repeated elsewhere, as the crayfish bait eliminates native species.


The use of crayfish as bait has been cited as one of the ways zebra mussels have spread to different waterways, as members of this invasive species are known to attach themselves to crayfish.

Food



Crayfish are eaten all over the world. Like other edible crustaceans, only a small portion of the body of a crayfish is edible. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. At crawfish boils
Seafood boil
Seafood boil is the generic term for any number of different kinds of social events in which shellfish is the central element. Regional variations dictate the kinds of seafood, the accompaniments and side dishes, and the preparation techniques . In some cases, a boil may be sponsored by a community...

 or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten.

Claws of larger boiled specimens are often pulled apart to access the meat inside. Another favourite is to suck the head of the crayfish, as seasoning and flavour can collect in the fat of the boiled interior. A popular double entendre
Double entendre
A double entendre or adianoeta is a figure of speech in which a spoken phrase is devised to be understood in either of two ways. Often the first meaning is straightforward, while the second meaning is less so: often risqué or ironic....

 laden phrase heard around crawfish season in Louisiana derives from this practice: "suck the head; pinch the tail".

A common myth is that a crawfish with a straight tail died before it was boiled and is not safe to eat. In reality, crawfish that died before boiling can have curled tails as well as straight, as can those that were alive, and may very well be fine to eat. Boiled crawfish which died before boiling are safe to eat if they were kept chilled before boiling and were not dead for a long time. (This does not mean that a sack of crawfish that are all dead should be boiled.) A much better test than the straight tail as to the edibility of any crawfish is the tail meat itself; if it is mushy, it is usually an indication that it should be avoided.

Like all crustaceans, crayfish are not kosher because they are aquatic animals that do not have both fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...

s and scales
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...

. They are therefore not eaten by observant Jews.

Scandinavia


Crayfish is a popular dish in 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....

 and Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

, and is by tradition primarily consumed during the fishing season in August. The boil is typically flavored with salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

, sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...

, ale
Ale
Ale is a type of beer brewed from malted barley using a warm fermentation with a strain of brewers' yeast. The yeast will ferment the beer quickly, giving it a sweet, full bodied and fruity taste...

, and large quantities of stems and flowers of the dill
Dill
Dill is a perennial herb. It is the sole species of the genus Anethum, though classified by some botanists in a related genus as Peucedanum graveolens C.B.Clarke.-Growth:...

 plant. While most Americans eat them warm, the Swedes and Finns normally eat them cold. One traditional Finnish practice is to eat crayfish with a vodka chaser. The catch of domestic freshwater crayfish, Astacus astacus
Astacus astacus
Astacus astacus, the European crayfish, noble crayfish or broad-fingered crayfish, is the most common species of crayfish in Europe, and a traditional foodstuff. Like other crayfish, Astacus astacus is restricted to fresh water, living only in unpolluted streams, rivers and lakes...

, and even of a transplanted American species, Pacifastacus leniusculus
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...

, is very limited, and to satisfy demand, the majority of what is consumed has to be imported. Sales depended on imports from Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 for several decades, but after a decline in supply, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

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

 are today the biggest sources of import.

Russia and Ukraine


In Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 and Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

, crayfish are a traditional seasonal appetizer that is used as an accompaniment to beer and liquor. Although native varieties tend to be larger (usually, Astacus astacus
Astacus astacus
Astacus astacus, the European crayfish, noble crayfish or broad-fingered crayfish, is the most common species of crayfish in Europe, and a traditional foodstuff. Like other crayfish, Astacus astacus is restricted to fresh water, living only in unpolluted streams, rivers and lakes...

), rampant freshwater pollution and years of overfishing largely limit availability to imports--most from Armenia, Kazakhstan and China. Prior to cooking, the crustaceans are soaked in water or milk, then boiled live for 7-15 minutes in rapidly boiling salted water with additional ingredients, such as carrots, onion
Onion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

, dill
Dill
Dill is a perennial herb. It is the sole species of the genus Anethum, though classified by some botanists in a related genus as Peucedanum graveolens C.B.Clarke.-Growth:...

, parsley
Parsley
Parsley is a species of Petroselinum in the family Apiaceae, native to the central Mediterranean region , naturalized elsewhere in Europe, and widely cultivated as an herb, a spice and a vegetable.- Description :Garden parsley is a bright green hairless biennial herbaceous plant in temperate...

, bay leaf
Bay leaf
Bay leaf refers to the aromatic leaf of the bay laurel . Fresh or dried bay leaves are used in cooking for their distinctive flavor and fragrance. The leaves are often used to flavor soups, stews, braises and pâtés in Mediterranean cuisine...

, peppercorns. More extravagant preparations include such ingredients as white wine, beer, sour cream
Sour cream
Sour cream is a dairy product rich in fats obtained by fermenting a regular cream by certain kinds of lactic acid bacteria. The bacterial culture, which is introduced either deliberately or naturally, sours and thickens the cream. Its name stems from the production of lactic acid by bacterial...

, cloves, caraway seed, coriander seed, chili peppers, stinging nettle
Stinging nettle
Stinging nettle or common nettle, Urtica dioica, is a herbaceous perennial flowering plant, native to Europe, Asia, northern Africa, and North America, and is the best-known member of the nettle genus Urtica...

, etc. Russians rarely incorporate crayfish into complex dishes and, unlike other cultures, they usually consume the entire crayfish, short of the shell and the antennae. Russian and Ukrainian fascination with crayfish goes back quite far and generates considerable lore. An old proverb: "When there is no fish, even crayfish is a fish." A proverb of more recent vintage: "Summer heat is thirst; thirst is beer; beer is crayfish!" There are as many myth associated with picking the freshest live crayfish as there are for picking ripe watermelons. Russians and Ukrainians, generally, will not cook fresh crayfish if the crustaceans are dead or perceptibly lethargic. (But pre-boiled frozen specimens are acceptable.)

France


In France, dishes with a base or garnish of crayfish are frequently described as .

Spain


In Spain, crayfish is called (lit. "river crab"). They used to be widely consumed, especially in Castile and León
Castile and León
Castile and León is an autonomous community in north-western Spain. It was so constituted in 1983 and it comprises the historical regions of León and Old Castile...

 and Aragon
Aragon
Aragon is a modern autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. Located in northeastern Spain, the Aragonese autonomous community comprises three provinces : Huesca, Zaragoza, and Teruel. Its capital is Zaragoza...

, but over-fishing and the introduction of non-native crayfish species (e.g. Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

, commonly called ) led to a dramatic decline in crayfish population. Nowadays they remain as a seasonal delicacy, usually stewed in tomato sauce, although fishing the native crayfish is strictly forbidden since the species is nearly extinct. Instead of the native crayfish, it is common to fish Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

 or Pacifastacus leniusculus, also present in most of the Spanish rivers.

United States


Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

 supplies 98% of the crayfish (referred to locally as crawfish) harvested in the United States. In 1987, Louisiana produced 90% of the crayfish in the world, 70% of which were consumed locally. In 2007, the Louisiana crawfish harvest was about 54,800 ton, almost all of it from aquaculture.

About 70%–80% of crayfish produced in Louisiana are Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

 (red swamp crawfish), with the remaining 20%–30% being Procambarus zonangulus (white river crawfish). Despite the large-scale production in Louisiana, most frozen crayfish available in supermarkets in other states are Chinese imports.

Louisiana crawfish are usually boiled live in a large pot with heavy seasoning (salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

, cayenne pepper
Cayenne pepper
The cayenne pepper—also known as the Guinea spice,cow-horn pepper, aleva, bird pepper,or, especially in its powdered form, red pepper—is a red, hot chili pepper used to flavor dishes and for medicinal purposes. Named for the city of Cayenne in French Guiana, it is a cultivar of Capsicum annuum...

, lemon
Lemon
The lemon is both a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The fruit is used for culinary and non-culinary purposes throughout the world – primarily for its juice, though the pulp and rind are also used, mainly in cooking and baking...

, garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

, bay leaves, etc.) and other items such as potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

es, corn on the cob
Corn on the cob
Corn on the cob is a culinary term used for a cooked ear of freshly picked maize from a cultivar of sweet corn. The ear is picked while the endosperm is in the "milk stage" so that the kernels are still tender...

, onion
Onion
The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

s, garlic
Garlic
Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...

, mushroom
Mushroom
A mushroom is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground on soil or on its food source. The standard for the name "mushroom" is the cultivated white button mushroom, Agaricus bisporus; hence the word "mushroom" is most often applied to those fungi that...

s and sausage
Sausage
A sausage is a food usually made from ground meat , mixed with salt, herbs, and other spices, although vegetarian sausages are available. The word sausage is derived from Old French saussiche, from the Latin word salsus, meaning salted.Typically, a sausage is formed in a casing traditionally made...

. There are many differing methods used to season a crawfish boil, and an equal number of opinions on which one is correct. They are generally served at a gathering known as a crawfish boil
Seafood boil
Seafood boil is the generic term for any number of different kinds of social events in which shellfish is the central element. Regional variations dictate the kinds of seafood, the accompaniments and side dishes, and the preparation techniques . In some cases, a boil may be sponsored by a community...

. Other popular dishes in the Cajun
Cajun cuisine
Cajun cuisine is the style of cooking named for the French-speaking Acadian or "Cajun" immigrants deported by the British from Acadia in Canada to the Acadiana region of Louisiana, USA. It is what could be called a rustic cuisine — locally available ingredients predominate, and preparation...

 and Creole cuisines of Louisiana include crawfish étouffée
Étouffée
Étouffée or etouffee is a dish found in both Cajun and creole cusine typically served with shellfish over rice. It is most popular in New Orleans and in the bayou country of the southernmost half of Louisiana.-Etymology:...

, fried
Deep frying
Deep frying is a cooking method in which food is submerged in hot oil or fat. This is normally performed with a deep fryer or chip pan; industrially, a pressure fryer or vacuum fryer may be used....

 crawfish, crawfish pie, crawfish dressing, crawfish bread and crawfish beignet
Beignet
A beignet in the U.S. is a pastry made from deep-fried dough, much like a doughnut, and sprinkled with confectioner's sugar, or frostings. Savory versions of beignets are also popular as an appetizer, with fillings such as maple or fruit preserves....

s.

Mexico


The Mexican crayfish locally named acocil
Acocil
Acocil is a species of crayfish native to Mexico, Cambarellus montezumae. The name acocil comes from the Nahuatl , meaning "crooked one of the water" or "squirms in the water". It is a traditional foodstuff of the Pre-Columbian Mexicans, who boiled or baked the animal, and ate it in tacos...

 was a very important nutrition source of the ancient Mexican Aztec
Aztec
The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...

 culture. Other regional names for crayfish are chacales, chacalines and langostas de río. Today, crayfish is consumed mainly boiled, similarly to crayfish dishes in other parts of the world, or prepared with typically Mexican sauces and condiments, particularly in central and southern Mexico. Traditional preparations include soups, tacos and "cocktails" similar to shrimp dishes.

Nigeria


Crayfish are usually smoked, and occasionally sun-dried, and they form an indispensable food item in the diet of the people of the entire southern states in particular and Nigeria as a whole. It is a core of Nigerian cooking.

China


The culinary popularity of crayfish swept across mainland China in the late 1990s. Crayfish is generally served with Mala
Sichuan mala
Mala sauce refers to a popular Chinese oily spicy and numbing sauce which consists of Sichuanese peppercorn, chili pepper and various spices simmered with oil....

 flavour (a combined flavour of Sichuan pepper and hot chili) or otherwise plainly steamed whole, to be eaten with a preferred sauce. In Beijing
Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...

, the ma la flavoured crayfish is shortened to "ma xiao" and is often enjoyed with beer in a hot mid-summer evening.

Australia


Australia is home to genus Cherax
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...

 which is distinct from European, Asian and North American species. Two of the Australian edible crayfish are the freshwater yabby or yabbie
Common yabby
The common yabby, Cherax destructor, is an Australian freshwater crustacean in the Parastacidae family. It is listed as a vulnerable species of crayfish by the World Conservation Union , though the validity of this listing is questionable; wild yabby populations remain strong, and have expanded...

 (C. albidus-destructor
Common yabby
The common yabby, Cherax destructor, is an Australian freshwater crustacean in the Parastacidae family. It is listed as a vulnerable species of crayfish by the World Conservation Union , though the validity of this listing is questionable; wild yabby populations remain strong, and have expanded...

) and the red claw (C. quadricarinatus). Yabbie is closest in size to the North American species, but is not considered to be commercially viable outside Australia because of its relatively slow growth and small size. The expression "throw yabbie on the barbie" was popularized in the US by actor Paul Hogan
Paul Hogan
Paul Hogan, AM is an Australian actor best known for his role as Michael "Crocodile" Dundee from the Crocodile Dundee film series, for which he won a Golden Globe award.-Early life and career:...

 (known as Crocodile Dundee
Crocodile Dundee
"Crocodile" Dundee is a 1986 Australian comedy film set in the Australian Outback and in New York City. It stars Paul Hogan as the weathered Mick Dundee and Linda Kozlowski as Sue Charlton....

) when he used it in several TV commercials. The freshwater yabbie is often confused with shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 or prawns, in part because the name yabby also applies to a species of marine ghost shrimp that is inedible and is only usable as bait. The "red claw" crayfish are twice the size of North American crawfish and they contain 30% edible "meat" compared to P. clarkiis 15%. Other Australian species are fairly rare and thus usually are not used for food. Their slow growth generally makes them inefficient for aquaculture.

Pets



Crayfish are kept as pets in freshwater aquariums. They prefer foods like shrimp pellets or various vegetables, but will also eat tropical fish food, regular fish food, algae wafers, and even small fish that can be captured by their claws. Their disposition towards eating almost anything will also cause them to explore the edibility of aquarium plants in a fish tank.

When keeping a crayfish as a pet, it is suggested they are provided with a hiding space. At night, some fish become less energetic and settle to the bottom. The crayfish might see this as a chance for an easy meal, or a threat, and injure or kill the fish with its claws. Crayfish are effective scavengers and will consume fish carcasses. They sometimes will consume their old exoskeleton after it has moulted.

Since crayfish are accustomed to being in ponds or rivers, they will have a tendency to shift gravel around on the bottom of the tank, creating mounds or trenches to emulate a burrow. Crayfish will often try to climb out of the tank, especially if an opening exists at the top that they can fit through. Crayfish kept as pets in the United States from local waters are usually kept with bluegill
Bluegill
The Bluegill is a species of freshwater fish sometimes referred to as bream, brim, or copper nose. It is a member of the sunfish family Centrarchidae of the order Perciformes.-Range and distribution:...

 or bass
Bass (fish)
Bass is a name shared by many different species of popular gamefish. The term encompasses both freshwater and marine species. All belong to the large order Perciformes, or perch-like fishes, and in fact the word bass comes from Middle English bars, meaning "perch."-Types of basses:*The temperate...

, rather than goldfish
Goldfish
The goldfish is a freshwater fish in the family Cyprinidae of order Cypriniformes. It was one of the earliest fish to be domesticated, and is one of the most commonly kept aquarium fish....

 or other tropical or subtropical fish.

However, most species of dwarf crayfish, such as Cambarellus patzcuarensis
Cambarellus patzcuarensis
Cambarellus patzcuarensis is a crayfish in the family Cambaridae.-Description:It has a body measuring , including claws. Most specimens found in the wild are brown, sometimes with a gray or blue tint. Cambarellus patzcuarensis var...

, will not destructively dig or eat live aquarium plants. They are also relatively non-aggressive and can even be kept safely with dwarf shrimp. Because of their very small size of 1.5 inches (3.8 cm) or less, some fish are often a threat to the crayfish rather than the other way around.

In some nations, such as the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

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

, 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...

, and 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...

, imported alien crayfish are a danger to local rivers. The three species commonly imported to Europe from the Americas are Orconectes limosus
Orconectes limosus
Orconectes limosus is a species of crayfish in the family Cambaridae. It is native to the east coast of North America, from Maine to the lower James River, Virginia, but has also been introduced to Europe. It is unusual in that it lives in silty streams, rather than the clear water usually...

, Pacifastacus leniusculus and Procambarus clarkii
Procambarus clarkii
Procambarus clarkii is a freshwater crayfish species, native to the Southeastern United States, but found also on other continents, where it is often an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.-Range and...

. Crayfish may spread into different bodies of water because specimens captured for pets in one river are often released into a different catchment. There is a potential for ecological damage when crayfish are introduced into non-native bodies of water (e.g., 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...

 in Europe).

Further reading

  • Sterling K. Johnson and Nathan K. Johnson. 2008. Texas Crawdads. College Station, Texas. ISBN 978-0-9801103-0-2 available from Crawdad Club Designs
  • Jerry G. Walls, "Crawfishes of Louisiana". Baton Rouge, LA. Florida State University Press, 2009 ISBN 978-0-8071-3409-2

External links