Dolphin

The dolphin is a sea mammal that lives in oceans and some rivers around the world. Dolphins are not fish. They breathe air, give birth to live babies, and feed their young with milk, just like cows and humans do. There are about 40 different kinds of dolphins. The bottlenose dolphin is the most famous, but the biggest dolphin is the orca, also called the killer whale.

Most dolphins are between 6 and 12 feet long. They have smooth, rubbery skin, a curved mouth that looks like a smile, and a blowhole on top of their head. To breathe, a dolphin pops up to the surface and blows air out of the blowhole. It can hold its breath for about 10 minutes. Some dolphins can dive more than 1,000 feet down, deeper than three football fields stacked end to end.

Dolphins find their food using a skill called echolocation. The dolphin makes a series of clicks that travel through the water, bounce off objects, and come back to its ears. From those echoes, the dolphin can tell how far away a fish is, how big it is, and even whether it is hiding in the sand. Bats use the same trick in the air. Dolphins eat fish, squid, and shrimp.

Dolphins live in family groups called pods. A pod can have just a few dolphins or more than a thousand. They work together to hunt. One trick used by bottlenose dolphins in Florida is called mud-ring feeding. One dolphin swims in a circle and stirs up a ring of mud around a group of fish. The fish panic and leap out of the ring, right into the mouths of waiting dolphins.

Dolphins are some of the smartest animals on Earth. They can learn tricks, solve puzzles, and recognize themselves in a mirror, which most animals cannot do. Each dolphin has its own signature whistle, almost like a name, that other dolphins use to call it. Scientists are still trying to figure out how much dolphins actually say to each other, and whether their whistles and clicks add up to something like a language.

People and dolphins have a long history together. Ancient Greek coins showed dolphins. Sailors have told stories for thousands of years about dolphins guiding lost ships or pushing drowning swimmers back to shore. Some of those stories are probably true, and some are probably not.

Today most kinds of dolphins are doing okay, but some are in serious trouble. The vaquita, a tiny dolphin relative living in the Gulf of California, has fewer than 20 animals left. Fishing nets, pollution, and boat noise are the biggest dangers dolphins face.