Since dolphins swim in the water many people think that they must be fish. However, dolphins are in fact warm-blooded mammals that breathe air and give birth to baby dolphins rather than lay eggs. This fact alone makes dolphins unique creatures, but they also have many more characteristics that make them one of the most interesting animals on the planet.

Dolphins and some whales are cetaceans and part of a whale group known as odontocetes. Basically this means that they all have teeth. Whales that don't have teeth to eat with are mysticetes. Dolphin teeth are cone-shaped, and it's these teeth that set them apart from other sea animals.

Most dolphins inhabit the tropical and pleasantly warm waters throughout the world. What most people don't realize is that there are other dolphin species living in rivers and non-salt water. There are so few of them left, that they are considered endangered.

Fifty-seven different species of dolphin make up the world's population today. Dolphins have sleek bodies and their noses, called "rostrum", are long and beak-like. Many of us think that dolphins and porpoises are related, when in fact they are not. One thing that makes them different is their teeth. As mentioned the dolphin's are cone shaped and the porpoise have teeth that look more like spades. This enables them to dig for food among rock. The other major difference is the fact that porpoise are able to live in water that's colder than a dolphin can even tolerate.

Orcas are the most easily identified and best known dolphin. They are more commonly known as killer whales. People tend to think of the Orca as among the most violent and frightening sea animals. This is probably due to the fact that they are large and seem fearless in the water.

Female dolphins are pregnant for twelve months before delivering their babies, or calves as they are known. The calves weigh between 30 and 40 pounds and are about 30 inches long. They will nurse from their mothers until they are two years old.

Even after they're weaned, the dolphin calf will swim and play with its mother for between five and seven years. During this time the young dolphin will learn how to find food and to interact socially with its relatives.

Dolphins live in groups known as "pods" and travel together. The females interact with the young, while the males keep more to themselves and don't participate in parenting.

Dolphins are amazingly intelligent and curious. These traits make them intriguing to us, along with the fact that dolphins love to interact with humans. They are always ready to tell us all about what's going on in the waters around us, but unfortunately we aren't able to understand them.