Signal crayfish

Signal crayfish (Pacifastacus leniusculus) is a species of crayfish native to North America. It is also known as the Pacific freshwater crayfish and the North American river crab.

Description

Signal crayfish are large, reaching up to 16-18 cm in length. They are named for the conspicuous white to pale blue patches on the underside of their claws, which appear like 'signals'. The body color varies from brownish to greenish, with a tan or yellowish underside.

Distribution and habitat

Originally from the Pacific Northwest region of North America, signal crayfish have been introduced to other parts of the world, including Europe and Japan. They inhabit a variety of freshwater habitats, including rivers, lakes, and streams.

Ecology

Signal crayfish are omnivorous, feeding on a variety of plant and animal matter. They play a significant role in their ecosystems, contributing to nutrient cycling and serving as both predators and prey.

Impact on native species

In areas where they have been introduced, signal crayfish can have a significant impact on native species. They compete with native crayfish for resources and can spread crayfish plague, a fungal disease to which they are resistant but many native crayfish are not.

Conservation

Efforts to control the spread of signal crayfish include trapping and removal, as well as public education about the risks of releasing non-native species into the wild.

See also

• Crayfish plague
• Invasive species
• Pacific Northwest

‎