2011-12-27

Kōura




Crayfish

Crayfish
Temporal range: Mesozoic–Recent
Northern koura, Paranephrops planifrons (Parastacidae)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
Infraorder: Astacidea
Superfamily: Astacoidea
Latreille, 1802
Parastacoidea
Huxley, 1879
Families
Astacoidea
Parastacoidea

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related. They breathe through feather-like gills 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, although some species such as the invasive Procambarus clarkii are more hardy. Crayfish feed on living and dead animals and plants.

In Australia, 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 koura, from the indigenous Australian and Māori names for the animal respectively, or by other names specific to each species. An exception is the freshwater Murray crayfish, which belongs to the family Parastacidae and is found on Australia's Murray River.

The study of crayfish is called astacology.

Names

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 western regions, and "crawfish" further south, although there are considerable overlaps.

Anatomy

Geographical distribution and classification

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.

Crayfish were introduced purposely into a few Arizona 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 has over 100 species in a dozen genera. Many of the better-known Australian crayfish are of the genus Cherax, and include the marron (now believed to be two species, Cherax tenuimanus and C. cainii), red-claw crayfish (Cherax quadricarinatus), 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 up to 5 kilograms (11 lb) and is found in the 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 record

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.

Crayfish plague

Uses

Bait

Crayfish are commonly sold and used as bait, either live or with only the tail meat, and are good at attracting channel catfish, largemouth bass, pike and muskellunge. 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, on the Fox River and Des Plaines 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.

Crayfish covered with zebra muscles.jpg

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

Scandinavia

Crayfish is a popular dish in Sweden and Finland, and is by tradition primarily consumed during the fishing season in August. The boil is typically flavored with salt, sugar, ale, and large quantities of stems and flowers of the dill 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, and even of a transplanted American species, Pacifastacus leniusculus, is very limited, and to satisfy demand, the majority of what is consumed has to be imported. Sales depended on imports from Turkey for several decades, but after a decline in supply, China and the United States are today the biggest sources of import.

Russia and Ukraine

In Russia and Ukraine, crayfish (раки, sing. рак) 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), 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, dill, parsley, bay leaf, peppercorns. More extravagant preparations include such ingredients as white wine, beer, sour cream, cloves, caraway seed, coriander seed, chili peppers, stinging nettle, 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 (écrevisse) are frequently described as à la Nantua.

Spain

In Spain, crayfish is called cangrejo de río (lit. "river crab"). They used to be widely consumed, especially in Castile and León and Aragon, but over-fishing and the introduction of non-native crayfish species (e.g. Procambarus clarkii, commonly called cangrejo americano) 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 or Pacifastacus leniusculus, also present in most of the Spanish rivers.

United States

Louisiana 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 (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, cayenne pepper, lemon, garlic, bay leaves, etc.) and other items such as potatoes, corn on the cob, onions, garlic, mushrooms and sausage. 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. Other popular dishes in the Cajun and Creole cuisines of Louisiana include crawfish étouffée, fried crawfish, , crawfish dressing, crawfish bread and crawfish beignets.

Mexico

The Mexican crayfish locally named acocil was a very important nutrition source of the ancient Mexican Aztec 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 flavour (a combined flavour of Sichuan pepper and hot chili) or otherwise plainly steamed whole, to be eaten with a preferred sauce. In Beijing, the ma la flavoured crayfish (麻辣小龙虾) is shortened to "ma xiao" (麻小) and is often enjoyed with beer in a hot mid-summer evening.

Australia

Australia is home to genus Cherax which is distinct from European, Asian and North American species. Two of the Australian edible crayfish are the freshwater yabby or yabbie (C. albidus-destructor) 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 (known as Crocodile Dundee) when he used it in several TV commercials. The freshwater yabbie is often confused with shrimp 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. clarkii's 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

References

Further reading

External links

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Pacific oysters
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& spiny lobsters Crabs Crayfish Others

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