Crayfish, also known as crawfish, crawdads, crawlfish, crawldads, freshwater lobsters, mountain lobsters, mudbugs, or yabbies, are freshwater crustaceans resembling small lobsters (to which they are related). Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some species are found in brooks and streams where there is running fresh water, while others thrive in swamps, ditches, and paddy fields. Most crayfish cannot tolerate polluted water, although some species such as Procambarus clarkii are hardier. Crayfish feed on animals and plants, either living or decomposing, and detritus.
Temporal range: Mesozoic–Recent
|Northern kōura, Paranephrops planifrons (Parastacidae)|
The name "crayfish" comes from the Old French word escrevisse (Modern French écrevisse). The word has been modified to "crayfish" by association with "fish" (folk etymology). The largely American variant "crawfish" is similarly derived.
Some kinds of crayfish are known locally as lobsters, crawdads, mudbugs, and yabbies. In the Eastern United States, "crayfish" is more common in the north, while "crawdad" is heard more in central and southwestern regions, and "crawfish" further south, although there are considerable overlaps.
The study of crayfish is called astacology.
In Australia (on the eastern seaboard), New Zealand and South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster, of the genus Jasus that is indigenous to much of southern Oceania, while the freshwater species are usually called yabby or kōura, from the indigenous Australian and Māori names for the animal respectively, or by other names specific to each species. Exceptions include western rock lobster (of the Palinuridae family) found on the west coast of Australia; the Tasmanian giant freshwater crayfish (from the Parastacidae family) found only in Tasmania; and the Murray crayfish found along Australia's Murray River.
In Singapore, the term crayfish typically refers to Thenus orientalis, a seawater crustacean from the slipper lobster family. True crayfish are not native to Singapore, but are commonly found as pets, or as an invasive species (Cherax quadricarinatus) in the many water catchment areas, and are alternatively known as freshwater lobsters.
The body of a decapod crustacean, such as a crab, lobster, or prawn (shrimp), is made up of twenty body segments grouped into two main body parts, the cephalothorax and the abdomen. Each segment may possess one pair of appendages, 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. Walking legs have a small claw at the end.
There are three families of crayfish, two in the Northern Hemisphere and one in the Southern Hemisphere. The Southern Hemisphere (Gondwana-distributed) family Parastacidae lives in South America, Madagascar and Australasia, and is distinguished by the lack of the first pair of pleopods. Of the other two families, members of the Astacidae live in western Eurasia and western North America and members of the family Cambaridae live in eastern Asia and eastern North America.
The greatest diversity of crayfish species is found in southeastern North America, with over 330 species in nine genera, all in the family Cambaridae. A further genus of astacid crayfish is found in the Pacific Northwest and the headwaters of some rivers east of the Continental Divide. Many crayfish are also found in lowland areas where the water is abundant in calcium, and oxygen rises from underground springs.
In 1983, Louisiana designated the crayfish, or crawfish as they are commonly referred, as their official state crustacean. Louisiana produces 100 million pounds of crawfish per year with the red swamp and white river crawfish being the two most popular species to harvest. Crawfish are a special part of Cajun culture dating back hundreds of years. A variety of cottage industries have developed as a result of commercialized crawfish iconology, such as products with crawfish attached to wooden plaques, T-shirts with crawfish logos, and crawfish pendants, earrings and necklaces made of gold or silver.
Australia has over 100 species in a dozen genera. In Australia, many of the better-known crayfish are of the genus Cherax, and include the marron from Western Australia (now believed to be two species, Cherax tenuimanus and C. cainii), red-claw crayfish (Cherax quadricarinatus), common yabby (Cherax destructor) and western yabby (Cherax preissii). The marron are some of the largest crayfish in the world. They grow up to several pounds in size. C. tenuimanus is critically endangered, 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 Astacopsis gouldi, which can achieve a mass of over 5 kilograms (11 lb) and is found in rivers of northern Tasmania, and the Murray crayfish Euastacus armatus, which can reach 2 kilograms (4.4 lb) and is found in much of the southern Murray-Darling basin.
Fossil records of crayfish older than 30 million years are rare, but fossilised burrows have been found from strata as old as the late Palaeozoic or early Mesozoic. The oldest records of the Parastacidae are in Australia, and are 115 million years old.
Some crayfish suffer from a disease called crayfish plague, caused by the North American water mould Aphanomyces astaci which was transmitted to Europe when North American species of crayfish were introduced there. Species of the genus Astacus are particularly susceptible to infection, allowing the plague-coevolved signal crayfish to invade parts of Europe.
Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is eaten. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. At crawfish boils or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten. Like all crustaceans, crayfish are not kosher because they are aquatic animals that do not have both fins and scales. They are therefore not eaten by observant Jews.
As of 2005, Louisiana supplies 95% of the crayfish harvested in the US. In 1987, Louisiana produced 90% of the crayfish harvested in the world, 70% of which were consumed locally. In 2007, the Louisiana crawfish harvest was about 54,800 tons, almost all of it from aquaculture. About 70%–80% of crayfish produced in Louisiana are Procambarus clarkii (red swamp crawfish), with the remaining 20%–30% being Procambarus zonangulus (white river crawfish).
Crayfish are preyed upon by a variety of ray-finned fishes, and are commonly used as bait, either live or with only the tail meat. They are a popular bait for catching catfish, largemouth bass, smallmouth bass, striped bass, perch, pike and muskie. When using live crayfish as bait, anglers prefer to hook them between the eyes, piercing through their hard, pointed beak which causes them no harm; therefore, they remain more active.
When using crayfish as bait, it is important to fish in the same environment where they were caught. An Illinois State University report that focused on studies conducted on the Fox River and Des Plaines River watershed stated that rusty crayfish, initially caught as bait in a different environment, were dumped into the water and "outcompeted the native clearwater crayfish." Other studies confirmed that transporting crayfish to different environments have led to various ecological problems, including the elimination of native species. Transporting crayfishes as live bait has also contributed to the spread of zebra mussels in various waterways throughout Europe and North America, as they are known to attach themselves to exoskeleton of crayfishes.
Crayfish are kept as pets in freshwater aquariums, typically with bluegill or bass, rather than goldfish or tropical or subtropical fish. They prefer foods like shrimp pellets or various vegetables, but will also eat tropical fish food, regular fish food, algae wafers, and small fish that can be captured with their claws. A report by the National Park Service as well as video and anecdotal reports by aquarium owners indicate that crayfish will eat their molted exoskeleton "to recover the calcium and phosphates contained in it." As omnivores, crayfish will eat almost anything; therefore, they may explore the edibility of aquarium plants in a fish tank. However, most species of dwarf crayfish, such as Cambarellus patzcuarensis, will not destructively dig or eat live aquarium plants. They are also relatively non-aggressive and can be kept safely with dwarf shrimp.
In some nations, such as the United Kingdom, United States, Australia, and New Zealand, imported alien crayfish are a danger to local rivers. The three species commonly imported to Europe from the Americas are Orconectes limosus, Pacifastacus leniusculus and Procambarus clarkii. 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 in Europe, or the introduction of the common yabby (Cherax destructor) into drainages east of the Great Dividing Range in Australia.
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, living only in unpolluted streams, rivers, and lakes. It is found from France throughout Central Europe, to the Balkan Peninsula, and north as far as parts of the British Isles, Scandinavia, and Eastern Europe. Males may grow up to 16 cm long, and females up to 12 cm.Austropotamobius pallipes
Austropotamobius pallipes is an endangered European freshwater crayfish, and the only species of crayfish native to the British Isles. Its common names include white-clawed crayfish and Atlantic stream crayfish.Bisque (food)
Bisque is a smooth, creamy, highly seasoned soup of French origin, classically based on a strained broth (coulis) of crustaceans. It can be made from lobster, langoustine, crab, shrimp, or crayfish.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 the United States east of the Great Divide and Mexico, but fewer range north to Canada, and south to Guatemala and Honduras. Three live on the island of Cuba. The species in the genus Cambaroides are the only found outside North America, as they are restricted to eastern Asia.A few species, including the invasive Procambarus clarkii and Orconectes rusticus, have been introduced to regions outside their native range (both in North America and other continents). Conversely, many species have tiny ranges and are seriously threatened; a few are already extinct.A 2006 molecular study suggested that the family Cambaridae may be paraphyletic, with the family Astacidae nested within it, and the status of the genus Cambaroides remains unclear.Cambarus
Cambarus is a large and diverse genus of crayfish from the United States and Canada. The adults range in size from about 5 centimeters (2 in) up to approximately 15 centimeters (6 in).Caridoid escape reaction
The caridoid escape reaction, also known as lobstering or tail-flipping, refers to an innate escape mechanism in marine and freshwater crustaceans such as lobsters, krill, shrimp and crayfish.
The reaction, most extensively researched in crayfish, allows crustaceans to escape predators through rapid abdominal flexions that produce powerful swimming strokes—thrusting the crustacean backwards through the water and away from danger. The type of response depends on the part of the crustacean stimulated, but this behavior is complex and is regulated both spatially and temporally through the interactions of several neurons.Chicken Marengo
Chicken Marengo is a French dish consisting of a chicken sautéed in oil with garlic and tomato, garnished with fried eggs and crayfish. The dish is similar to chicken à la Provençale, but with the addition of egg and crayfish, which are traditional to Chicken Marengo but are now often omitted. The original dish was named to celebrate the Battle of Marengo, a Napoleonic victory of June 1800.Crayfish as 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 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.Like all crustaceans, crawfish are not kosher because they are aquatic animals that do not have both fins and scales. They are therefore not eaten by observant Jews. During the Middle Ages in Scandinavia, "crayfish were counted among the insects, and that sort of animal nobody would put away in the mouth".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. The tradition has also spread to Finland via its Swedish-speaking population. A similar tradition exists in the Baltic countries in particular in Lithuania and Latvia.
Crayfish parties are generally held during August, a tradition that began because the crayfish harvest in Sweden was, for most of the 20th century, legally limited to the late summer. Nowadays, the kräftpremiär date in early August has no legal significance. Dining traditionally takes place outdoors, but in practice the party often takes refuge indoors due to the bad weather or aggressive mosquitoes. Customary party accessories are novelty paper hats, paper tablecloths, paper lanterns (often depicting the Man in the Moon), and bibs. A rowdy atmosphere prevails amid noisy eating and traditional drinking songs (snapsvisa). Alcohol consumption is often high, especially when compared to the amount of food actually consumed. It is considered customary to suck the juice out of the crayfish before shelling it.
Akvavit and other kinds of snaps are served, as well as beer. The crayfish are boiled in salt water and seasoned with fresh dill – preferably "crown dill" harvested after the plant has flowered – then served cold and eaten with the fingers. Bread, mushroom pies, surströmming, strong Västerbotten cheese, salads and other dishes are served buffet-style.Kaikoura
Kaikoura (; Māori: "Kaikōura", from "Te Ahi Kaikōura a Tama ki te Rangi") is a town on the east coast of the South Island of New Zealand. It is located on State Highway 1, 180 km north of Christchurch.
Kaikoura became the first local authority in the Southern Hemisphere to achieve recognition by the EarthCheck Community Standard.The town has an estimated permanent resident population of 2,150 (as of June 2018). The town is the governmental seat of the territorial authority of the Kaikoura District, which is politically a part of the Canterbury region.The infrastructure of Kaikoura was heavily damaged in the 2016 Kaikoura earthquake, which also caused two deaths in the area. The bay and surrounding region was uplifted by as much as 2 metres.List of endangered arthropods
As of July 2016, the International Union for Conservation of Nature (IUCN) lists 616 endangered arthropod species. 6.5% of all evaluated arthropod species are listed as endangered.
The IUCN also lists 27 arthropod subspecies as endangered.
No subpopulations of arthropods have been evaluated by the IUCN.
For a species to be considered endangered by the IUCN it must meet certain quantitative criteria which are designed to classify taxa facing "a very high risk of extinction". An even higher risk is faced by critically endangered species, which meet the quantitative criteria for endangered species. Critically endangered arthropods are listed separately. There are 1010 arthropod species which are endangered or critically endangered.
Additionally 2875 arthropod species (30% of those evaluated) are listed as data deficient, meaning there is insufficient information for a full assessment of conservation status. As these species typically have small distributions and/or populations, they are intrinsically likely to be threatened, according to the IUCN. While the category of data deficient indicates that no assessment of extinction risk has been made for the taxa, the IUCN notes that it may be appropriate to give them "the same degree of attention as threatened taxa, at least until their status can be assessed."This is a complete list of endangered arthropod species and subspecies as evaluated by the IUCN.Orconectes
Orconectes is a genus of freshwater crayfish, native to the eastern United States and Canada. It includes the rusty crayfish, an invasive species in North America, and Orconectes limosus, an invasive species in Europe.Orconectes virilis
Orconectes virilis is a species of crayfish known as the virile crayfish, northern crayfish, Eastern Crayfish and lesser known as the Lake Crayfish or Common Crawfish. It is native to eastern United States and southeast Canada.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.Procambarus clarkii
Procambarus clarkii is a species of cambarid freshwater crayfish, native to northern Mexico, and southern and southeastern United States, but also introduced elsewhere (both in North America and 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.Sagmariasus
Sagmariasus verreauxi is a species of spiny lobster that lives around northern New Zealand, the Kermadec Islands the Chatham Islands and Australia from Queensland to Tasmania. It is probably the longest decapod crustacean in the world, alongside the American lobster Homarus americanus, growing to lengths of up to 60 centimetres (24 in).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. The signal crayfish is now considered an invasive species across Europe, Japan, and California ousting native species there.Spiny lobster
Spiny lobsters, also known as langustas, langouste, or rock lobsters, are a family (Palinuridae) of about 60 species of achelate crustaceans, in the Decapoda Reptantia. Spiny lobsters are also, especially in Australia, New Zealand, Ireland, South Africa, and the Bahamas, called crayfish, sea crayfish, or crawfish ("kreef" in South Africa), terms which elsewhere are reserved for freshwater crayfish.