Dolphins HITCHHIKE
Watching playful dolphins keep up with speeding boats, diving and leaping near the front, or bow, you'd think that these marine animals must be incredibly fast swimmers. Pacific white-sided dolphins can swim about 17 miles (27.4 kilometers) an hour. Most of the boats dolphins play with travel much faster. How do dolphins keep up? The boat creates a pressure wave as it pushes through the water. Dolphins surf on this bow wave, cleverly getting a ride at speeds they couldn't manage on their own.

Stunning SOUNDS
Like most bats, dolphins use sound to "see". They use echolocation—making a sound and listening to it bounce off objects—for finding food and navigating without bumping into things. While hunting for food underwater, some dolphins also make very loud clicking sounds that may knock out any small fish or squid within range. The dolphins then gobble up the sound-stunned prey.

Leftover LEGS
Millions of years ago, dolphins had legs. If you look closely at a dolphin's skeleton, you'll see two small rod-shaped pelvic bones. These bones may be leftover hind legs that some scientists think mean the dolphin's ancestors walked around on land. They say dolphin ancestors looked like wolves but were more closely related to modern-day cows.

Toothy JAWS
If dolphins had dentists, those docs would be busy. Some dolphins have even more teeth than crocodiles. Their extremely long jaws may contain as many as 250 pointy white teeth. Unlike predatory crocodiles, though, dolphins aren't interested in chomping on human swimmers. There are no reliable reports of wild dolphins attacking people.

Terrific TEAMWORK
Thousands of dolphins sometimes gather in huge pods, or groups. These super pods spread across several miles of open ocean. Dolphins often hunt together. That allows them to cover larger areas as they look for schools of fish. Dolphins also cooperate to round up their prey. Sometimes they work together to herd a big school of fish into a small, crowded clump. Then the dolphins take turns speeding through the trapped fish to eat.

Fishermen's HELPERS
Dolphins often hang around people in boats, playing in bow waves with frequent spectacular leaps. Fishermen tell tales of dolphins helping them by herding fish into their nets. In southern Brazil, bottlenose dolphins signal fishermen when it's the best time to cast their nets. According to town records, dolphins have been guiding the fishermen for more than 150 years. What's in it for the dolphins? Apparently the Brazilian bottlenoses enjoy the leftovers that the fishermen leave behind.

Name-CALLERS
Dolphins communicate with whistles and use individual "names" to identify one another. Some research scientists who study dolphin communication think that wild dolphins have special high-pitched calls known as signature whistles that they use to tell pod pals apart. Each dolphin chooses its own signature whistle, usually by its first birthday. This name stays the same for at least ten more years.

Favorite AUNT
Cooperation among dolphins is crucial to a newborn. When a mother dolphin is ready to give birth, a second dolphin called an auntie will stay nearby to help. As soon as the baby is born, its mother gently nudges the newborn to the surface for its first breath of air. Often the auntie will help with this important chore.

Practical JOKES
Just like people, dolphins seem to enjoy a good prank. One dolphin, Ake, used to be rewarded for helping clean her tank. She’d bring leaves or other bits of debris to her trainer in exchange for a fish treat. Soon the trainer noticed that when Ake couldn’t find debris, she made her own! She’d peel paint off the side of the tank to give in return for a treat! Clever Ake!

Freshwater SWIMMERS
A few rare dolphins live in fresh water. While most dolphin species live in the salt water of the ocean, there are five species that live in rivers and streams. The Irrawaddy dolphin (left) lives in southern Asia, as do two other species. The baiji dolphin, on the brink of extinction, lives in China’s Yangtze River. The boto dolphin of the Amazon and Orinoco Rivers of South America is unique: it’s pink!