Several times a day they indulge in very active play, darting with mock ferocity after each other, or leaping quite clear of the water and striking with heavy splashes. They often swim on their backs, with the jaws out of water, or on their sides repeatedly striking the surface with the head. When leaping a favorite trick is to throw the body around until the dorsal fin is forward, with a resulting splash that sends the spray quite out on the floor. A high leap by one of them is usually a signal that starts them all to leaping. Our fears that they might leap quite out of the pool were unfounded; they are clever enough to avoid the wall which surrounds them.
Another game is played by going around the pool with short dives, each time striking the surface with the flat of the tail. When the pool is entirely full of water their play is livelier than when the water level is lowered. The increased depth gives them more confidence and they often turn complete forward and backward somersaults.
The ordinary swimming motion of the tail is up and down, but, if playfully charged by a companion, the porpoise seems to make a spurt ahead by more or less side action of the tail. This is not easy to determine, however, and may be more apparent than real, as the water is too much disturbed by high speed dashes for accurate observation. The animal undoubtedly relies upon its tail for propulsion, the flippers or pectoral fins being brought into action in making turning movements. Several of the porpoises have lately taken to swimming on their backs, and the movement of the flippers and tail at such times is easily seen contrasted with the white under parts. In swimming on the back, however, there is considerable lateral action of the tail.
Frequently three or four of them will bunch together in the center of the pool, rolling and rubbing against each other in a ball-like mass suggestive of the tussling of puppies. This may at times mean that they are merely scratching, as the single porpoise kept in the Aquarium for two and a half months last summer frequently rubbed his sides or back against the back of a large sturgeon kept in the same pool. This injured porpoise indulged in no play and swam day and night in the same circle from right to left, but always fed freely.
There is considerable mobility of the neck of the porpoise, an animal lacking all outward appearance of a neck. The head can be turned down at an angle of about 45 degrees to the body, and can be turned as far sideways with equal readiness. These motions can be seen at feeding time and when the animals are tossing fishes.
There is no evidence that the porpoise can see out of water. In throwing a fish the head is often thrust well above the surface, but the animal seems to be always intent on its plaything, entirely disregarding the visitors leaning over the rail five or six feet away. While a fish thrown into the water is promptly seized, the porpoise pays no attention to a fish suspended by a thread two inches above the surface. If the eyes of porpoises and other whales were fitted for observation above the surface of the water, as are the eyes of seals, they might long ago have learned to use them in the same way.[[18]]
[18]. I do not believe that because the porpoise would not seize a fish suspended above the water, it is evidence that it could not see it. Not being accustomed to take its food out of the water, the animal probably did not know what the fish was. A wounded porpoise which I kept alive for some time on a ship in the Pacific could see my hand if it was brought within a few feet of its eyes. R. C. A.
Porpoises instantly recognize any change that may occur in connection with the water level of the pool. The entirely noiseless opening of a distant valve to lower the water is apparent to them and may stop their play temporarily. A pool only thirty-seven feet in diameter does not of course afford space for the high activity of which the porpoise is capable. Nevertheless they often leap three feet or more clear of the surface, sometimes striking the water forcibly enough to throw spray thirty feet into the air. The visitor soon gets the impression that they enjoy life even in captivity and their keepers, while always vigilant as to their needs, have ceased to be concerned about their safety, regarding them as almost domesticated animals.
Photo by E. R. Sanborn.
“The captive porpoises are very lively, and keep swimming day and night, rising to blow usually with each circuit of the pool.”