Conservation photographer Paul Nicklen has been documenting the wildlife in the arctic regions of the world for decades, often getting dangerously up close with the animals he encounters in the sea and on land.
National Geographic contributing photographer Joel Sartore is 11 years into a 25-year endeavor to document every captive animal species in the world using studio lighting and black-and-white backgrounds. So far, he's photographed 6,500 different species, which leaves approximately 6,000 to go.
Robert Sullivan's Rats: Observations on the History & Habitat of the City's Most Unwanted Inhabitants chronicles the year he spent studying alley rats in New York City. He says you'd be surprised at what picky eaters they can be.