The animals of the Cordata period live in all the environments of the world. Many of these species live on land. Many species of aquatic cordata live in freshwater or in the ocean. Many species are tree- dwellers , desert dwellers , polar dwellers , house dwellers , and ants. Many of the animals in the Cordata episode live as parasites, attached to the bodies of other animals. The reason that the cordata episode is improved is because many animals have spines in this episode. And that's why the Cordata episode is an advanced episode.