Part of a small family in the order cetacea known as phocoenidae, porpoises are small cousins of whales and dolphins. Only six species of porpoise exist in the world’s oceans, all of which resemble miniature whales or beakless dolphins. Found mainly in the seas of the northern hemisphere, they are stout, torpedo-shaped, fully aquatic mammals with under-developed dorsal fins and small flippers.
The finless porpoise is found mainly in the coastal waters and river deltas of southeast Asia from Pakistan to the coasts of Japan. It is the smallest of all cetaceans growing to a maximum of around 6 feet in length and up to 99 pounds in weight. Sometimes referred to as the black finless dolphin, it is actually a dark gray color with shades of blue and a paler underside. Instead of a dorsal fin the species has a small ridge on its back meaning that at a distance it has an eel-like body shape. It is similar to all cetaceans in that it is a carnivore and feeds on a variety of fish and oceanic invertebrates.
A resident of the coastal waters in the southern hemisphere, the spectacled porpoise is found around South America, New Zealand and several of the islands of the Indian ocean. It is larger than the finless porpoise reaching lengths over 7 feet and weighing as much as 250 pounds. It is a blue-black color with a pure white underside and black markings around the lips and eyes that form a spectacle-like appearance. It has a pronounced triangular dorsal fin and small rounded flippers when compared to other porpoise species. Like all other porpoises, it has small spade-shaped teeth, a feature that differs from their cousin the dolphin who has round peg-like dentition.
One of the smaller porpoise species, the harbor porpoise, grows to just over 6 feet in length and averages about 115 pounds in weight. Native to the northern oceans, it is found most often in bays or river estuaries near the coast. It can be found as far north as the arctic coast and south towards the Mediterranean. It tends to be dark gray to black in color with a paler underside. Like the spectacled porpoise, it has a small triangular dorsal fin but larger, more rounded flippers. Being a mainly coastal species it tends to be slow moving compared to more oceanic porpoise species.
The Vaquita is shorter in length than the finless porpoise growing to just under 5 feet at most but with a larger, heavier body that weighs up to 121 lbs. It has a very limited home range only being found in the northern part of the Gulf of California and only close to the shoreline. Unlike most porpoise species, it tends to like these warmer coastal waters while the others like in colder regions. It leads a more solitary life than other porpoises and can be found living alone or in very small groups. It resembles the harbor porpoise in appearance although it is notably smaller and more slender.
Native to the coastal waters of South America down both coastlines, Burmeister’s porpoise grows to 6 feet in length and up to 154 lbs in weight. It is a very stout-bodied species with a small triangular dorsal fin and sharp curved flippers. It is dark gray to black in color with a pale almost white underside and lighter gray patches around the eyes which help distinguish the species.
The largest of all porpoises is still small compared to the majority of cetacens. Dall’s porpoise grows in excess of 7 feet in length and weighs well over 400 lbs when fully grown. It has a larger, more powerful body than the other porpoise species and can be more varied in color. Dall’s porpoise can be uniformly white or black, have black and white stripes or a dark body with a pale underside. This species prefers the colder arctic waters of the northern Pacific and can be found as far south as the Californian coast and in the waters of Japan.