The classification of animal groups is essential to the development of modern biology—but it's extremely complicated. Trying to shoehorn the messy, complicated web of interrelationships that is ...

A look at many of the more than 22,000 species of fish, from freshwater, to the deep ocean, to the colorful coral reef. We look at the origin of fish, how they breathe, why they have scales, and how ...

A young girl welcoming you inside a zoo, inside of which are a walrus and a zebra, and a horse Classification is the process of organising living things into categories. These categories help us to ...