Harbor porpoises eat squid, octopus, and fish, including herring, cod, sardines, pollock, and whiting. Everyday, they must eat the equivalent weight of 10% of their body weight to maintain their metabolism.

The harbor porpoise is a part of the cetacea order and the Phocoenidae family. It is in the same family as other small marine mammals with short flippers. 

The harbor porpoise is small and stocky. They are dark grey or brown with light grey sides and white underbelly. Its mouth and snout are small. The flippers are also small with a rounded shape. The average length of a harbor porpoise is 5 feet, but they can reach up to 6 feet. The average weight is less than 150 lbs. Unlike many animals, the female harbor porpoise is larger than the male.

The harbor porpoise lives in cold, coastal waters. They can be found in the waters of the Arctic, North Pacific, North Atlantic, Black Sea, and Mediterranean. They like to live in bays, fjords, harbors, large rivers, and estuaries, but they do journey to deeper waters during the colder months.

The harbor porpoise is a fairly solitary animal. They can sometimes be spotted in small groups, but generally spend much of their time alone. They do not often dive deep. When they are seen breathing at the water’s surface, they mostly roll their backs out of the water to collect air, but they do sometimes jump into the air.