Astacus astacus, commonly known as the European crayfish, is a freshwater crustacean found in rivers, lakes, and ponds across Europe. It has a robust body, typically measuring between 10 to 15 centimeters in length, and is characterized by its large claws and a hard exoskeleton. This species prefers clean, well-oxygenated waters and is often associated with aquatic vegetation. The European crayfish plays a vital role in its ecosystem by helping to maintain the balance of aquatic life. It is an omnivore, feeding on plants, insects, and detritus. However, Astacus astacus faces threats from habitat loss and competition with invasive species, leading to a decline in its populations in some areas.