DOLPHIN OR PORPOISE
There is still considerable controversy over the correct usage of the terms dolphin and porpoise. As mentioned in the preceding section, common names of any species may vary from locale to locale and even from individual to individual. Some persons argue for the use of the term porpoise for all small cetaceans. Others insist on the term dolphin. Still others either randomly use the terms or call members of the family Delphinidae dolphins and members of the family Phocoenidae porpoises. The evidence supporting any one of these positions is confusing at best and no usage of terms appears to be without problems. We see no wholly satisfactory resolution to the problem at this time. For all these reasons, we have little desire to defend our decision to follow the last of these practices in this guide, referring to all members of the family Delphinidae for which the term dolphin or porpoise appears in the common name as dolphins, and to the one member of the family Phocoenidae represented in the western North Atlantic, Phocoena phocoena, as the harbor porpoise. Although all cetaceans may be regarded as whales, the term "whale" most commonly applies to the larger animals. For all species treated, other common names by which they may be known are also listed.
Detailed treatment of the relative merits of the various terminologies is inappropriate here. Furthermore, it is our opinion that the usage of the terms dolphin, porpoise, and whale as part of the common names of cetaceans is largely a matter of personal preference.