Page:South - the story of Shackleton's last expedition, 1914-1917.djvu/490

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The subdivision of whalebone whales is one of degree in the size of the whalebone. These whales have enormously muscular tongues, which press the water through the whalebone lamellae and thus, by a filtering process, retain the small food organisms. The food of the whalebone whales is largely the small crustacea which occur in the plankton, though some whales (humpback, fin whales, and sei whales) feed also on fish. The stomachs examined at South Georgia during December 1914, belonged to the three species, — humpbacks, fin whales, and blue whales, and all contained small crustacea — Euphausiæ, with a mixture of amphipods. The toothed whales — sperms and bottlenoses — are known to live on squids, and that there is an abundance of this type of food in the Weddell Sea was proved by an examination of penguin and seal stomachs. Emperor penguins (and hundreds of these were examined) were invariably found to contain Cephalopod "beaks," while large, partly digested squids