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（中国就是这种）. Crayfish feed on living and dead animals and plants. （麻辣小龙虾是食腐动物哦）。
In Australia, New Zealand and South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster, of the type 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.
