Approximately 78 species of whales,
dolphins, and porpoises are included in the Order Cetacea. Cetaceans are broken
into two Suborders, or main groups, Mysticeti (baleen whales) and Odontoceti
(toothed whales). There are 11 species of baleen whales and 67 species of
toothed whales. Cetaceans are relatively large, generally characterized by
streamlined bodies that glide easily through the marine environment.
Porpoises tend to be smaller but
stouter than dolphins. They have small, rounded heads and blunt jaws instead of
beaks. While dolphins have a round, bulbous "melon", porpoises do not.
Their teeth are spade-shaped, whereas dolphins have conical teeth. In addition,
a porpoise's dorsal fin is generally triangular, rather than curved like that of
many dolphins and large whales. Some species have small bumps, known as
tubercles, on the leading edge of the dorsal fin. The function of these bumps is
Members of the porpoise, or the
Phocoenidae family, have blunt heads and small spade-shaped teeth. Porpoises
grow up to 7 feet (2.1 meters) in length a. Porpoise species include the
harbour porpoise, Gulf of California porpoise,
Incidental mortality in fishing gear
is the most immediate threat facing porpoises other human activities represent
potential dangers to this population. Foremost among these is continued
degradation and loss of habitat. Threats to porpoise habitat may be a direct
result of human activities (e.g. porpoises excluded from habitat by coastal
development such as salmon farming) or occur indirectly, through the effects of
pollution and eutrophication in coastal ecosystems.
Difference Between Dolphins
While dolphins and porpoises are very similar and people often use the
term interchangeably, scientists generally agree that there are four major
differences between dolphins and porpoises:
cone-shaped teeth while porpoises have flat or spade-shaped teeth.
•Dolphins usually have a pronounced “beak,” while porpoises do not
have a beak.
•Dolphins generally have a very curved or hooked dorsal fin, while
porpoises have a triangular dorsal fin.
•Porpoises are generally smaller than dolphins.
For more information on Whales,
Dolphins and Porpoise click on the logos below
Credit: The National Marine Mammal Laboratory,
FAO Fisheries Global Information System, The Illinois State Academy of Science,
American Cetacean Society, School of Biological Sciences, University of
California , The United States Navy
compiled from The British Antarctic Study, NASA, Environment Canada,
UNEP, EPA and other sources as stated and credited Researched by Charles
Welch-Updated daily This Website is a project of the The Ozone Hole Inc.
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