Dolphins belong to a group of mammals called cetaceans.
Dolphins are related to porpoises.
The main difference between dolphins and porpoises is in their snouts and teeth. The most common dolphin is the bottle-nosed dolpin. Dolphins are considered to be among the most intelligent of all animals. The Wild Dolphin Project - This site gives good information on dolphins and how to help save them. Habitat and Distribution - This site gives information about where dolphins live throughout the world.