A shark is a long-bodied marine fish with a cartilaginous skeleton, a prominent dorsal fin, and multiple rows of teeth. That's what the dictionary says. But few people know that sharks were roaming the oceans 400 million years ago—long before dinosaurs existed—or that sharks can smell a single drop of blood in the ocean from three miles away.

Curious readers will love exploring amazing facts about sharks and the sea creatures that share their habitat in this fascinating guide to their underwater world.