National Geographic : 1940 Jan
THE NATIONAL GEOGRAPHIC MAGAZINE Killers hunt for seals and penguins along the edge of pack ice and around large floes. At times when seals are basking or have taken refuge near the edge of thin ice, a school of Killers will suddenly come up beneath and endeavor to dislodge them by breaking the ice with their backs. In the fall at the time fur seal pups are learning to swim, packs of Killer Whales cruise back and forth in the coastal waters of the Pribilof Islands, devouring hundreds of the babies. They swallow young walruses whole. Fish of all sizes also form part of their food. White Whale (Delphinapterus leucas) White Whales are most numerous during the summer months in Arctic seas and adjacent waters as far south as Okhotsk Sea, Kodiak Island, St. Lawrence River, and Great Britain (Plate XIII). Shallow coastal waters and bays are their favorite haunts, but they also ascend rivers. White Whales have been seen in the Yukon River 600 miles from salt water and they travel up the St. Lawrence River as far as Quebec. Near Greenland, fishermen have used motor boats to surround and drive schools of White Whales into shallow water. On the Greenland coast they are caught in large-meshed nets supported by floats and laid outward from the shore. Leather shoestrings are manufactured from their hides and oil from the blubber. Adult White Whales are readily distinguish able from all other cetaceans by being entirely white and by having the dorsal fin reduced to a mere ridge. They are generally 12 to 14 feet long. Ten teeth are typically present in each upper jaw and eight in each lower jaw. Newborn calves are gray and subsequently assume shades of slate, brownish gray, or hair brown. Calves eight feet in length are gen erally mottled with chocolate brown. As the calves approach maturity, they assume a yel lowish color before acquiring the adult milk white skin. The White Whale is a fast swimmer, attain ing a speed of at least six miles an hour. and readily outdistances the Narwhal. It is usually very shy and sensitive to movements or sounds in or on the water, but is said to disregard those emanating from the land. White Whales consume large quantities of fish, squids, and prawns. When salmon are running in Okhotsk Sea during July and August, the whales are especially abundant off the mouths of rivers. Dall's Porpoise (Phocoenoides dalli) One of the creatures most frequently noticed by passengers on steamships following the In- side Passage from Seattle, Washington, to Juneau, Alaska, is this black and white por poise (Plate XIV). Less frequently it is seen around Kodiak Island and among the Aleutians. During June it has been sighted as far south as the Santa Barbara Channel off southern California. A first cousin (P. truci) of this species fre quents the waters around northern Japan. It differs from Dall's Porpoise in having the white area on the sides extending forward beyond the flippers. Both types are restricted to the North Pacific Ocean. When Dall's Porpoise breaks the water at the surface, the white lateral area contrasting sharply with the jet-black body and the low triangular dorsal fin serve as instant recogni tion marks. There is a strong dorsal longitu dinal ridge in front of the tail flukes. Dall's Porpoise measures, when fully grown, as much as 6 feet 2 inches and weighs about 200 pounds. Its food consists almost entirely of squids, but occasionally small fish, such as the saddled blenny, are eaten. The presence of this fish in the stomach contents suggests that this porpoise, when feeding, may nose around sub merged rocks along the shore. Right Whale Dolphin (Lissodelplhis borealis) Small schools of these dolphins wander about in the vast depths of the North Pacific Ocean. generally far offshore, from the latitude of San Diego, California, to Bering Sea (Plate XIV). On the other side of the Pacific they are found off the coasts of Japan. Right Whale Dolphins are so called because of the absence of a dorsal fin, a character they share with the larger Right Whale (Plate III). Rather slender in proportion to its length and having a short but distinct beak, this dolphin attains a length of at least eight feet. It is per haps the sleekest and handsomest of all the dol phins, the velvet-black color of the upper parts, the flippers, and the tail flukes contrasting with the white areas on the underparts. Our knowledge of this dolphin's actions when swimming rests solely on the observations of Titian R. Peale, who accompanied the United States Exploring Expedition of 1838-42 com manded by Charles Wilkes, U. S . N. He re ported them to be remarkably quick and active and said they frequently leap out of water. They feed largely on cuttlefish and fish. P6ron's Dolphin (L. peronii), a related spe cies, inhabits the southern seas from the longi tude of Chile to New Zealand and Tasmania. Its beak, as far as the eve. is silky white, and so are the sides, the flippers, the tail flukes, and the entire underparts: the top of the head and the back are black or bluish black. It is somewhat smaller than its northern relative, measuring about six feet in length.