called crawfish, crawdads, mudbugs, yabbies, or spoondogs, are
freshwater crustaceans (decapoda) resembling small lobsters, to
which they are closely related. They are found in bodies of fresh
water that do not freeze to the bottom, which are not polluted,
and which have shelter against predators. Some crayfish have been
found living as much as 3 m (10 feet) underground.
A Swedish lake
crayfishThere 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,
southern Africa, Madagascar and Australasia. Many Australian
crayfish are of the genus Cherax; and include the Marron (Cherax
tenuimanus), Red Claw Crayfish (Cherax quadricarinatus), Yabby
(Cherax destructor) and Western Yabby (Cherax preissii). The
world's largest crayfish, Astacopsis gouldi, is found in the
rivers of northern Tasmania. It can reach a weight of 4 kg.
The family Astacidae contains the native European crayfish,
as well as those in western North America, such as Pacifastacus.
The third family, Cambaridae, contains crayfish in east Asia
and eastern North America, such as Cambarus, and Zarigani, crayfish
indigenous to Japanese rivers and ponds.
& 2 Come From The U.S. Fish & Wildlife Service
Image Number 3 Is Courtesy of The USDA
Images 4 Through 9 Come From The NOAA