Harbour porpoises are the smallest whales in the world reaching a maximum length of two metres. They are easily distinguished from dolphins by their apparent lack of a 'beak' and flattened teeth. They are less gregarious than dolphins, preferring to keep in smaller gams of up 12 individuals. The sexes remain segregated until the breading season arrives. In the winter harbour porpoises migrate from northern waters to the coast of British Columbia and Washington state. Harbour porpoises occur along both Canadian coasts depending on the time of year. They are far less playful and curious than dolphins and will not frolic with or inspect visitors such as divers and boats. Their diet consists of both invertebrates, such as squid, and vertebrates, such as fish.