- Aquaculture
- Shellfish
Also
called CRAWFISH,
OR CRAWDAD, any of numerous crustaceans
(order Decapoda) constituting the families Astacidae (Northern
Hemisphere), Parastacidae, and Austroastracidae (Southern Hemisphere).
They are closely related to the lobster. Over half of the more
than 500 species occur in North America. Nearly all live in fresh
water, a few in brackish water or salt water.
Crayfish
are characterized by a joined head and thorax, or midsection,
and a segmented body, which
is sandy yellow, green, red, or dark brown in colour. The head
has a sharp snout, and the eyes are on movable stalks. The exoskeleton,
or body covering, is thin but tough. The front pair of the five
pairs of legs have large, powerful pincers. There are five pairs
of smaller appendages on the abdomen.
Crayfish
are usually about 7.5 cm (3 inches) long. Among the smallest is
the 2.5-centimetre-long Cambarellus diminutus of the southeastern
United States. Among the largest is Astacopsis gouldi of
Tasmania, which may reach 40 cm and weigh about 3.5 kg (8 pounds).
Crayfish,
common in streams and lakes, often conceal themselves under rocks
or logs. They are most active at night, when they feed largely
on snails, insect larvae, worms, and tadpoles; some eat vegetation.
Crayfish mate in the autumn and lay eggs in the spring. The eggs,
attached to the female's abdomen, hatch in five to eight weeks.
The larvae remain on the mother for several weeks. Sexual maturity
is achieved in a few months to several years, and the life span
ranges from 1 to 20 years, depending on the species.
The
most common genera of North America include Procambarus, Orconectes,
Faxonella, Cambarus, Cambarellus, and Pacifastacus. Austropotamobius,
the most common genus of Europe, is the only one native to Great
Britain. The genus Astacus occurs in Europe, the genus
Cambaroides in East Asia.
*Information found at
Britannica.com
