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Crayfish, also known as crawdads, crawfish, spiny lobsters, or aquatic cockroaches, are found in many lakes and streams in Arizona. They look like little lobsters, growing to about 3 inches in length. They have a joined head and thorax and a segmented body which is typically brown or greenish in color.

Natural History

The head has two pairs of sensory antennae and a pair of eyes on movable stalks. The appendages of the thorax include four pairs of walking legs and one pair of claw bearing arms, which it extends in front of its body while moving. These strong pinchers are specialized for cutting, capturing food, attack, and defense. Crayfish have a hard outside skeleton which provides protection and allows movement, but limits growth. As a result, the crayfish regularly gets too big for its skeleton, sheds it, and grows a new larger one. This is called molting and occurs six to ten times during the first year of rapid growth, but less often during the second year. For a few days following each molt, crayfish have soft exoskeletons and are more vulnerable to predators. 

Arizona is the only state with no native crayfish species, they were introduced by government agencies to control weeds and to feed bass and fishermen as bait. Unfortunately they have thrived and their presence has decimated aquatic plants and animals throughout the state. The AZ Department of Game and Fish has a brochure with additional information as well as tips for catching and cooking crayfish.

Crayfish prefer permanent, well-oxygenated ponds, lakes, rivers and streams with substrates of silt or rocks. They can live in water as shallow as a few inches to as deep as 100 feet and will tolerate water temperatures ranging from 33.8-89.6 F.

Crayfish are opportunistic feeders, eating both plants and animals, and can quickly outgrow predation by most fishes. They eat just about anything they can put their claws around, including aquatic plants, larval fish, snakes, turtles, insects and other invertebrates.Since Arizona has few natural agents to control them, crayfish populations have exploded. They have been implicated in a number of native species declines in Arizona, including leopard frogs, mud turtles, and endangered fish species such as the Little Colorado spinedace.

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