Astacoidea
Astacidae
Cambaridae
Parastacoidea
Parastacidae
Crayfish, often referred to as crawfish 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 crayfish 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.
In New Zealand the name crayfish (or cray) refers to a saltwater spiny lobster, of the type Jasus that is indigenous to much of southern Oceania. And crayfish are called freshwater crays or koura, the Māori name for the animal.