A sperm whale is the largest toothed predator on Earth, a massive ocean mammal that can grow longer than a school bus and dive deeper than almost any other air-breathing animal. These whales get their unusual name from a waxy substance called spermaceti found in their enormous, block-shaped heads.

Sperm whales are remarkable hunters. They dive thousands of feet into pitch-black ocean depths, using echolocation (clicking sounds that bounce off objects) to find their favorite prey: giant squid. These dives can last over an hour. The clicking sounds sperm whales make are so powerful they're considered the loudest animal-produced sounds in the world.

These whales have the largest brain of any animal, weighing about 17 pounds. They live in groups called pods and can be found in oceans around the world. Herman Melville's famous novel Moby-Dick features a white sperm whale, introducing many readers to these incredible animals. In the 1800s, sperm whales were heavily hunted for their oil, which was used in lamps and machinery, but today they're protected by international law.