It is hard to believe that the porpoise is not a fish, but a mammal. Yet it is just as much a mammal as the cow in the fields. Porpoises, dolphins and whales form the order called “Cetacea” of the group of aquatic mammals.

Actually, dolphins belong to the whale family and porpoises are a variety of dolphins. All these animals may be given the general name of whales, or cetaceans.