Joel Sartore is an American photographer on a 25 year long wildlife project.

Joel Sartore is an American photographer on a mission to capture images of all the animal species in zoos across the world - that's 12,000 creatures in some 40 countries. He's half-way through what he expects will be a 25-year project, called the National Geographic Photo Ark.

Image and credit: © Photo by Grahm S Jones, Columbus Zoo and Aquarium; After a photo shoot at the Columbus Zoo in Ohio, a clouded leopard cub climbs on Sartore's head. The leopards, which live in Asian tropical forests, are illegally hunted for their spotted pelts. Joel Sartore/National Geographic Photo Ark