This order includes all birds generally known as ducks, geese, swans and kamichis. It includes about 170 species at present. Anseriformes are found almost everywhere on Earth, except in the polar regions. They all live in aquatic environments. Anseriformes have anisodactyl webbed feet, i.e. the first digit is opposite the other digits. In Anatidae, the copulatory organ is partially or totally ossified. The beak is broad and flat and has thin internal horny lamellae. The young are nestlings, covered with a thick down, and are accompanied by their parents for a long time. They form the sister group to the Galliformes.