Anguilliformes is an order of fish commonly known as eels. These elongated, snake-like creatures are characterized by their long, cylindrical bodies and lack of pelvic fins. They inhabit various environments, including freshwater, brackish, and marine ecosystems, and are known for their ability to swim efficiently in tight spaces. Eels are found in many parts of the world and play important roles in their ecosystems as both predators and prey. Some species, like the European eel and American eel, are notable for their long migrations between freshwater spawning grounds and ocean habitats.