Introduction to Dolphins

People have long been fascinated with dolphins and porpoises. They have been celebrated in art and literature since the times of Ancient Greece. Even today, dolphins and porpoises are among the most popular of animals. Few people would forget an encounter with dolphins, especially one in which a group of wild dolphins comes over to a boat to "bow ride", or surf the wave that the boat makes as it travels through the water.

Dolphins, porpoises and whales are cetaceans.  Dolphins and porpoises are considered to be small whales.  All dolphins and porpoises are toothed whales (odontocetes.)  However, dolphins and porpoises differ in the type of teeth they have. Dolphins have sharp teeth, while porpoises have teeth that are spade or shovel shaped. In fact, scientists generally use tooth shape as a way of classifying dolphins and porpoises. Dolphins also tend to have a pointed mouth or "beak" and a fin on their backs, but not always.

All dolphins and porpoises use echolocation, which is similar to the sonar used on ships. Dolphins and porpoises produce a sound in the air passages in their heads.  An oil-filled organ, called the melon, focuses or directs the sound.  A sound wave might hit an object, such as a fish, and the sound wave then bounces, or echoes back to the dolphin or porpoise. They can use this echo to tell what kind of fish or other object has been located, how large it is, where it is and much more information about their environment. It is like seeing with their ears, but in some ways even better!

Dolphins and porpoises tend to be very social animals; they like to live in groups. Sometimes people come across huge schools or groups of dolphins, as many as thousands together. Dolphin and porpoise mothers generally take care of their calves for one to two years until they are old enough to survive on their own. Like all mammals, they provide milk to their young.

Dolphins and porpoises are found in virtually all oceans and major seas of the world. One family, the river dolphin, is even found in large freshwater rivers such as the Amazon in South America and rivers in China and India. Dolphins and porpoises range in size from the killer whale at a maximum of 30 feet in length and a weight of up to eight tons, to the small harbor porpoise, five to six feet long and weighing 100-200 pounds.

Large numbers of dolphins and porpoises are a sign of the health and vitality of our oceans. But unfortunately, tens of thousands of porpoises and dolphins are dying every year due to problems caused by people. Many accidentally get caught in fishing nets and drown. Others get entangled in old nets, which are loose and floating freely. Many near-shore dolphins and porpoises are exposed to pollution and toxins that can make them sick.  In some places, people still catch and eat dolphins and porpoises for food or to use as fishing bait. Many scientists are concerned that dolphins and porpoises now need to be protected in the same way that people worked to save and protect large whales from hunting in the recent past.

You can help dolphins and porpoises by keeping informed on current issues, by writing to government officials about your concerns and by supporting laws that protect dolphins and their ocean home. You can also recycle your trash and use less plastic (which is dangerous to these animals), buy products that are dolphin safe, and participate in beach clean ups.