The deep ocean is a challenging environment. There is no sunlight, the water is cold, and the pressure from the water above is immense. Despite these challenges, deep ocean habitats, such as deep sea canyons, are home to a wide variety of organisms. Many species of vertebrates, animals with a backbone, have adapted to life in these extreme conditions. Some deep-sea fishes have modified fins that function more like legs and feet than swimming aids. Others have extra large eyes or other light-sensing organs to help detect the slightest light from potential prey or predators. Others are bioluminescent and produce their own light which may be to attract food or even a mate.