- For the crustaceans commonly known as "sea crayfish", see spiny lobster.
Crawfish, often referred to as crayfish or crawdad, are freshwater crustaceans resembling small lobsters, to which they are closely related. They breathe through gills and are found in bodies of fresh 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 crawfish cannot tolerate polluted water, although some species such as the invasive Procambarus clarkii are more hardy. Some crayfish have been found living as much as 3 m (10 feet) underground.
The study of crawfish is called astacology .
The anatomy of crawfish may be found in the article "decapod anatomy".
Names
The name "crawfish" comes from the Old French word escrevisse (Modern French écrevisse) from Old Frankish *krebitja (cf. crab), from the same root as crawl. The word has been modified to "crawfish" by association with "fish" (folk etymology). The largely American variant "crawfish" is similarly derived.
In New Zealand the name crawfish (or cray) refers to a spiny lobster, and crawfish are called freshwater crays or koura, the Māori name for the animal.
Some kinds of crawfish are known locally as lobsters, crawdads, mudbugs and yabbies. In the Eastern United States, "crawfish" is more common in the north, while "crawdad" is heard more in central regions, and "crawfish" further south, although there are considerable overlaps.
CRAWFISH:Geographical distribution and classification
There are three families of crawfish, 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 crawfish species is found in south-eastern North America, with over 330 species in nine genera, all in the family Cambaridae. A further genus of astacid crawfish is found in the Pacific Northwest and the headwaters of some rivers east of the Continental Divide.
Australasia is another centre of crawfish diversity, with over 100 species in a dozen genera. Many of the better-known Australian crawfish are of the genus Cherax, and include the marron (Cherax tenuimanus), red-claw crawfish (Cherax quadricarinatus), yabby (Cherax destructor) and western yabby (Cherax preissii). The world's largest crayfish, Astacopsis gouldi, which can achieve a mass in excess of 3 kilograms, is found in the rivers of northern Tasmania.
Madagascar has a single (endemic) crayfish species, Astacopsis madagascarensis.
Europe is home to seven species of crayfish in the genera Astacus and Austropotamobius.
Cambaroides is native to Japan and eastern mainland Asia.
Crawfish-Molting
Crawfish also need to molt as they grow because their hard exoskeletons do not allow much room for expansion. Baby crayfish can molt on a daily basis but as they grow older, the regularity of molts decreases to a period of weeks or even months. The first few days after a molt, a crawfish's skin is very soft and it is very vulnerable to attacks from other animals and crayfish.
The early signs of molting include lack of appetite and a slow down in activity. During this period the crawfish ingests calcium into an internal organ, not into the exoskeleton.
When the crawfish is ready to molt, it will try to find a hiding spot. Then it will move onto its back and begin fanning its pincers, legs and swimmerets (under the tail) in order to get as much oxygen as possible. The carapace will begin to crack behind the head; the new appendages then pierce the old shell; and then after about five minutes, a sudden, violent movement will detach the old shell from the crawfish .
The freshly molted crawfish will invariably be larger as part of the growing process, but is vulnerable on several fronts. Firstly, the shell is very soft and vulnerable to predators, including other crawfish and fish. The crawfish needs to eat the old shell to replace the lost calcium and strengthen the weakened carapace.
Crawfish as a dish
Crawfish are eaten in Europe, China, Australia and the United States. 98% of the crawfish harvested in the United States come from Louisiana, where the standard culinary terms are crawfish or écrevisses.
Crawfish in Louisiana 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, onions, garlic, and sausage. They are generally served at a gathering known as a crawfish boil. Other popular crawfish dishes in the Cajun and Creole cuisines of Louisiana include crawfish étouffée, crawfish pie, crawfish bread, and crawfish beignets, and crawfish are an ingredient in chicken Marengo.
Crawfish is a popular dish in Scandinavia, 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 the flowers of the dill plant. The catch of domestic freshwater crawfish, 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.
The Mexican crawfish is named locally as Acocil and was a very important nutrition source of the ancient Mexican Aztec culture; now this kind of crawfish is consumed (mainly boiled) and prepared with typically Mexican sauces or condiments in central and southern Mexico.
In China, the culinary popularity of crawfish swept across Mainland China in the late 1990s. Crayfish is generally served in with ma la (麻辣) flavor (a combined flavor of Sichuan pepper and hot chili) or otherwise plainly steamed whole, to be eaten with a preferred sauce. In Beijing, the Ma La flavoured crawfish (麻辣小龙虾) is shortened to "Ma Xiao" (麻小) and is often enjoyed with beer in a hot mid-summer evening.
Like other edible crustaceans, only a small portion of the body of a crawfish 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 crawfish is presented, however, other portions may be eaten. Claws of larger boiled specimens are often pulled apart to get at the meat inside. Another favorite is to suck the head of the crayfish, as seasoning and flavor can collect in the boiled interior. A popular double entendre laden phrase heard around crawfish season in Louisiana derives from this practice: "Suck the head, eat the tail". The remainder of the body can either be used for decoration or is discarded.
Crawfish as pets
Crawfish are sometimes kept as pets in freshwater aquaria. They prefer foods like shrimp pellets or various vegetables but will also eat tropical fish food, algae wafers, and even small fish that come too close, such as goldfish or minnows. Their disposition towards eating almost anything will also cause them to consume most aquarium plants in a fish tank; however, crawfish are fairly shy and may attempt to hide under leaves or rocks. When keeping a crawfish as a pet, one must provide a hiding space. At night, some fish become less energetic and settle to the bottom. The crawfish might see this as a chance for an easy meal, or a threat, and injure or kill the fish with its claws. Crawfish are effective scavengers and will consume fish carcasses. Crawfish are great escape artists and may try to climb out of the tank, so any holes in the hood should be covered. In nations where imported alien crawfish are a danger to rivers, such as England, United States, Australia, and New Zealand, crawfish spread because specimens captured for aquariums in one river are often flung back into a different one. Because of the potential ecological damage from nonnative crawfish, crawfish kept as pets should never be released to the wild. The most humane way to dispose of a live crawfish is to freeze it