by Kathy Kranking
1. They're like you. Sure, dolphins live in the water and you live on land. And yes, they look more like fish than people. But dolphins are mammals, just as you are. So dolphins and people have lots of things in common, including being warm-blooded, breathing air with lungs, and nursing their young.
2. They come in lots of sizes. You're probably familiar with bottlenose dolphins (above). But there are more than 30 kinds of dolphins. The smallest are about as long as you are tall. And the biggest are almost as long as a school bus! You can't always tell a dolphin by its name: Orcas (killer whales), for example, belong to the dolphin family.
3. They're great athletes. Dolphins are acrobats. Maybe you've seen them at marine parks or aquariums, performing amazing flips and leaps. The most athletic dolphin of all is the dusky dolphin. Many dolphins leap out of the water as they swim. But duskies do somersaults. They also can flip three or four times in the air before splashing back into the water! Spinner dolphins are also very athletic. When they leap, they spin their bodies round and round in mid-air. They've been known to spin up to seven times before re-entering the water.
Dolphins perform their gymnastics for a number of different reasons. Depending on the type of dolphins, they may do it to communicate, to search for food, or just to have fun.
4. They "talk" to each other a lot. Dolphins communicate with sounds such as chirps, clicks, and whistles. Each dolphin has a special whistle that's different from other dolphins' whistles. If a dolphin mom and baby like the ones in the top photo ever get separated, they can call to each other using these special sounds.
5. They love to play! Just as you do, dolphins of all ages like to have fun, and they spend a lot of time each day playing. They'll jump, flip, somersault, and chase each other for the fun of it. And they'll play with almost anything, including seaweed, coral, bubbles—even trash. Groups of dolphins often invent their own games and pass them down to their young.
6. They like their "peeps." Dolphins are social animals. Most kinds hang out in small groups of five to ten dolphins (see top right photo). Sometimes lots of these small groups will join up with others for a short time to make a gigantic group with hundreds of dolphins.
7. They're smarties. Dolphins are able to learn many behaviors and can solve puzzles that scientists give them. The dolphin above has learned to copy its trainer when she sticks out her tongue! Scientists have even taught dolphins to understand a sign language where different hand or arm movements stand for words.
Some wild dolphins in Australia have learned to use "tools." For example, when they search the ocean bottom for food, they hold sponges over their snouts. This may protect them from sharp shells or rocks. Some scientists believe that dolphins may be Earth's most intelligent creatures after humans!
8. They "see" with sound. Dolphins have a neat trick for locating things around them. They use echoes. This is called echolocation. (See diagram above.) First a dolphin makes some clicking sounds by passing air between lip-like parts in its head called phonic lips. The sounds pass through another part in the dolphin's head, called the melon. The melon helps aim the sounds straight ahead (red lines). If the sounds hit something in front of the dolphin, they bounce back as echoes (blue lines). When the sounds come back to the dolphin, they travel through a fat-filled part of its jaw to its ears, which are inside its head.
By listening to the sounds, the dolphin can tell the size and shape of the object, as well as how far away it is and which way it's going. Check out the dolphin above left. Even though its eyes were covered, it was able to find and pick up a triangle its trainer threw into the water.
9. They lend a flipper. Some kinds of dolphins help each other when they're hunting for food. A group of dolphins will work together to circle a school of fish. They'll swim closer and closer, herding the school into a tighter and tighter ball (top left photo). Then the dolphins take turns rushing in to grab their dinner. In shallow water, some dolphins herd fish against the shore to trap them.
10. They're popular! Most people love dolphins. They've delighted us for centuries. They have appeared on ancient coins and ceramics, and in paintings and other art (see the mosaic at top right). Because of their grace, intelligence, and friendly looking faces, dolphins are some of the most popular animals on Earth. No wonder they look as if they're smiling!