There are six species in this family. Porpoises are found in all the oceans and often are found in rivers and bays. They are 4-7 feet in length and weigh around 250 pounds. Porpoises have rounded snouts, narrow flippers, and a triangular doral fin. Porpoises have spade-shaped teeth and eat fish, squid, and crustaceans. They have a blow hole and use echolocation to navigate and locate prey.