After analyzing your little brother for a few hours -- watching Tommy slurp up spaghetti, hang from the trees and roll around in mud -- you're convinced he's a wild animal. Strangers back up your claim, remarking that he must have been raised by wolves. However, even though Tommy is a bit rambunctious, he's completely domesticated.

There are many differences between your brother and true wild animals (most notably that the latter usually doesn't eat Italian food). Wild animals, whether they fly, swim, swing, jump, run, slither or burrow, must use their instinct and environmental adaptations to survive. There are hundreds of thousands of wild animals roaming our planet -- some are familiar faces, like giraffes; others are more unknown, like capybaras.

Being described as "cold-blooded" might offend some people, but amphibians and reptiles welcome the term. These sometimes slithery, slimy wild animals are found in almost every region of the world. Whether four-legged, two-legged or no-legged, amphibians and reptiles have been getting around for millions of years.

Birds and marine animals seem to live completely separate lives -- one flying high within the heavens, and one gliding through the murky depths. But what about birds that swim, like penguins, and fish that soar, like flying fish?

Faraway beasts like tigers and kangaroos might come to mind when someone mentions wild animals, but there's one group of creatures you encounter everyday. Insects and arachnids are part of the most diverse, abundant group of all the wild animals.

Whether furry or scaly, feathery or leathery and every texture in between, wild animals provide diversity and wonder to planet Earth. As humans continue to solve zoological mysteries, hopefully we may add to the list of known animals. Who knows, scientists may even discover a new species in your own backyard: Brotherus annoyingus.