Crayfish, or crawdad, are small crustaceans that look like tiny lobsters and live in West Virginia's rivers and streams. Their claws are used for defense and digging burrows in banks and stream beds. Each has a head/chest section called the cephalothorax (where the claws and walking legs attach) and an abdomen (tail) they use to swim backward fast.

West Virginia has about 30 species. The largest is the New River Crayfish at nine inches. Different species live in different places: some in big rivers, and others in small streams. Some crayfish live mostly underground in wet areas, digging tunnels that other animals (like frogs and snakes) use for shelter. Crayfish are vital; they eat many things and, in turn, are a key food source for animals like bass, otters, and raccoons.

Crayfish are one of the most endangered animal groups globally. In West Virginia, threats include sedimentation (dirt clogging streams) and invasive species. People sometimes release non-native crayfish (from fishing bait) into the water. These invasives fight and eliminate the native species.

The Guyandotte Crayfish is so rare it was listed as an endangered species in 2016.