The North American signal crayfish, scientifically known as Pacifastacus leniusculus, is a freshwater crustacean commonly found in rivers, lakes, and streams across North America. They are recognized by their distinctive coloration, which includes a dark green or brown body with bright red or orange spots on their claws. These crayfish play a vital role in aquatic ecosystems, serving as both predator and prey. Signal crayfish are omnivorous, feeding on a variety of organic materials, including plants, insects, and detritus. They are also known for their burrowing behavior, which helps aerate the sediment in their habitats. Due to their adaptability, they have been introduced to various regions outside their native range, sometimes leading to ecological concerns.