Dolphins and porpoises are closely related but they aren't the same! Both belong to the scientific suborder, Odontoceti, which means "toothed whales," but they have different families. Dolphins are part of the Delphinidae family while porpoises are members of the Phocoenidae family. Very scientific sounding, huh? I'll bet you know more about dolphins and porpoises than you think – test your knowledge about these marine mammals in a quiz!