National Geographic, the Encyclopedia of Life and Oceana.org are a few great resources for researching animals. These resources have detailed information about land animals, marine animals and much more.
The National Geographic website has a section dedicated to animals. The page has recent news articles, images and videos from Nat Geo Wild, the National Geographic channel. There is also an A to Z index on the National Geographic animals page. Clicking on the name of an animal brings up a page with information about the animal's habitat, average size and other information.
National Geographic magazines and books are also good sources of animal information. "Bird Watcher's Bible," "Illustrated Guide to Wildlife" and "The Last Lions" are just a few National Geographic books about animals. National Geographic books and magazine subscriptions are available for purchase from the organization's website. The books and magazines are also available to borrow or read at many libraries.
The Encyclopedia of Life is another source of animal information. The website features millions of Taxon pages, each based on a single species of animal or plant. The pages contain detailed information about the species, habitat maps, images, multimedia and other features.
Oceana.org also has information for researching marine animals, which is categorized by the animal type. There is also a full animal index to search the animal by name.