Up To Date 16+ Dolphins Animal Underwater. The 36 dolphin species share more than a few characteristics. 6) although they live underwater, the bottlenose dolphin must come up to the surface to breath air. Dolphin is a common name of aquatic mammals within the infraorder cetacea. Dolphin facts, photos and videos wild dolphins reach out and connect with people on a regular basis, and often joyfully interact with dogs and children on boating trips.