signal crayfish, pacifastacus leniusculus, climbs on stone in water at river bank. north american crayfish, invasive species

abdomen america animal autumn britain brook california claws closeup crayfish creek crustacean culture czech detail europe exoskeleton finland food freshwater germany great idaho invasive japan lake leniusculus lobster natural nature nocturnal nordic north oregon pacifastacus party pincers plague river signal spain spring stone summer sweden unpolluted washington water wild wildlife