The common porpoise, also known as the harbor porpoise, lives throughout the temperate coastal waters of the Northern Hemisphere. The porpoise prefers shallower waters and is most common in bays and harbors.
The shy, elusive mammals are the smallest cetaceans, reaching an average of about 5 feet and 120 pounds. While porpoises are able to dive to great depths, they prefer to remain near the water surface, emerging every 25 seconds to breathe. Unlike most of their dolphin relatives, porpoises bear a rounded head instead of a snout and prominent forehead. The neck of the common porpoise is short and indistinguishable from the rest of its body.