Phocoena phocoena is a species of porpoise, commonly known as the common porpoise. There are a few synonyms that can be used to refer to this species, including harbor porpoise, black porpoise, and puffing pig. These synonyms may be used in different regions or contexts, but all refer to the same species. The common porpoise is found in cold and temperate waters of the North Atlantic and North Pacific oceans. They are known for their playful behavior and distinctive appearance, with a rounded head and dark coloring on their dorsal side. Despite their popularity, common porpoises are endangered due to threats such as accidental entanglements in fishing gear and habitat loss.