Signalkreps

Freshwater crayfish typically 6-9 cm long, reaching 16-20 cm. Smooth carapace, brown to reddish above, with a distinctive white to pale blue-green patch at the hinge of each claw. Native to the Columbia River basin of western North America. Introduced to Europe from 1960 and established in 27 countries by 2009. A largely resistant carrier of crayfish plague (Aphanomyces astaci), which is fatal to European crayfish.