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Although the terms dolphin and porpoise are sometimes used
interchangeably to refer to any member of the group, biologists
recognizes three distinct families: True porpoises, Phocoenidae,
with six marine species River dolphins, Platanistidae, with
five freshwater species
True dolphins, Delphinidae, with more than thirty marine
species; including killer and pilot whales (National Marine
Mammal Laboratory)
There are distinct differences between dolphins and porpoises
that should be noted before continuing:
- Dolphins have a hook-shaped dorsal fin, porpoises have
a triangular dorsal fin.
- Dolphins have conical teeth, porpoises have flat-shaped
teeth
- Dolphins have a long, sharp snout, porpoises have a short,
blunt snout
- Dolphins may live in large pods, porpoises prefer pods
of two to four
- Dolphins produce sounds humans can hear, porpoise produce
inaudible sounds
Harbor Porpoise
Bottlenose Dolphin
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