Habitat
Porpoises are found mostly in coastal waters, often entering harbors and estuaries and swimming up rivers. The mommon, or harbor, porpoise, inhabits temperate and cold inshore waters of the Northern Hemisphere around western Europe, northeastern Asia, and northern North America. The California Gulf porpoise, or cochito, inhabits not only the Gulf of California but also the Gulf of Guinea and the Black Sea. Burmeister's porpoise is found in the Southern Hemisphere, living in the cool, shallow inshore waters off South America. The spectacled porpoise is found off the western coast of South America and around the Falkland and South Georgia islands. Dall's porpoise, the most active and sociable species, is found around northern Japan and off the coast of North America, from the Aleutian Islands to California. The finless porpoise, the only true tropical species, frequents the Indo-Pacific Ocean from Iran to Borneo and Japan.
Food and Hunting
Porpoises often feed in river estuaries, over submerged seabed ridges, or where sea currents meet-all places where fish congregate. Each species has its preferences, but they are all flesh eaters. For example, the finless porpoise likes crustaceans, while Dall's porpoise eats squid whenever possible. The common porpoise feeds on herring, sardines, and cod, which it often herds toward a sloping, sandy shore. A common porpoise needs 6 to 10 pounds of food a day, while the larger Dall's porpoise needs 20 to 25 pounds a day. Porpoises often form small groups of two to four members, and they may dive individually for prey. Usually they feed on small schools of fish, but if a large concentration of fish occurs, many groups will gather to feed. Porpoises hunt mainly by sight and by listening for fish. They swallow prey whole or bite it into large chunks.
Did you know?
Dall's porpoise is teh fastest of all porpoises. It speeds through the water at 12 to 15 knots. It is famous for it's "rooster" spray-a stream of water that arcs up over the head as it surfaces.
The finless porpoise, as it names suggests, has no dorsal fin. The female may carry her young on her back.
Porpoises have 50 to 120 teeth, which are flattened into a spade shape at the tip.
The common porpoise makes an explosive noise as it surfaces to exhale. It has been called a "puffing pig."
Distribution
Porpoises live in coastal waters almost throughout the north Pacific and western Indo-Pacific. They are also found in the temperate and sub-Antarctic waters of South America and around the Auckland Islands off New Zealand.
Size
Length: 4-7.5 feet, depending on species.
Weight: 50-350 lbs.
Lifestyle
Habit: Form groups of 2-20, but usually around 4.
Calls: Believed to have a large repertoire of sounds, including "clicks" used for echolocation.
Lifespan: 12-23 years, depending on speices.
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