Mr. Big does not look happy having his image immortalized on film.

But it's all a pose.

The photograph above shows an African lion strutting his stuff, doing what big cats do when confronted by a stranger. The resident of the Omaha Zoo charges and growls.

The man behind the picture is Joel Sartore, an experienced Nebraska-based freelance photographer with National Geographic magazine who is on a personal quest to document as many animal species on film as possible, before some disappear forever. He has launched the Biodiversity Project, a largely self-funded mission that has taken him around the world.

The author of "RARE: Portraits of America's Endangered Species" has been blogging about his efforts and displaying some of his unique work on his website and National Geographic's Field Test blog. Prints of his work can be purchased at his website.

CNN spoke recently with Sartore, just before he headed out on another assignment.

CNN: Why did you launch the Biodiversity Project?

Sartore: This project basically looks at any animal I can put on a black and white background that will hold still long enough to get a picture of. The point is to get people to look these creatures in the eye and see if they care. Do we care that we're losing half of all the world's species by the turn of the next century? We better care, because what happens to them will eventually happen to us. It's folly to think that we can drive every other species on the planet to extinction and it won't affect us somehow.
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