The world of animals is diverse, presenting an amazing variety of characteristics from the long ears on a rabbit to the wings on a bird to the beautiful feathers of the peacock. Animals live in a variety of environments-- forests, rivers, lakes, grasslands, marshes, mountains, deserts-- and as such, they vary greatly in the adaptations they use to deal with the challenges of their everyday lives. Each species has a specific set of traits that allow them to cope with the unique challenges their environment presents them. And yet, despite the fact that animals live in such different habitats, they face many of the same challenges; all animals must eat, drink, sleep, mate, reproduce, and survive. Thus, though animals may seem to have little in common, they actually share several internal and external characteristics that help them cope with these shared challenges. This website explores these similarities and differences in several areas of animal physiology to demonstrate that despite the commonalities of animal structure, form ultimately meets function.