Morning Edition

Seventy five years ago, before Theodor Geisel rocked the culinary world with green eggs and ham or put a red-and-white striped top hat on a talking cat, Geisel (who you probably know better as Dr. Seuss) was stuck on a boat, returning from a trip to Europe.

For eight days, he listened to the ship's engine chug away. The sound got stuck in his head and he started writing to the rhythm. Eventually, those rhythmic lines in his head turned into his first children's book: It was called And to Think That I Saw It on Mulberry Street.

To spend a day in the life of National Geographic photographer Joel Sartore, there are a few things you have to get used to. Really long drives, for one. Tigers charging at you. And, of course ... well ... messes.

"I'm the only studio portrait photographer I know whose subjects routinely poop and pee on the background right in front of me," he says from behind the lens.