and though they are small creatures, only about five feet long, they are very good examples of the whale shape, with their tapering bodies, broad tails, and the back fin, which is found in some whales and not in others. Sometimes they swim quietly, only rising to breathe, and then they work the tail gently from side to side; at others they gambol and frolic, and jump right out of the water, beating the tail up and down, and bending like a salmon when he leaps; and whether they come quietly or wildly, you may generally know they are near by the frightened mackerel and herrings, which spring out of the water to avoid them. For the porpoises have a row of sharp teeth in each jaw, more than a hundred in all, and they bite, kill, and swallow in one gulp, without waiting to divide their food, so that they make sad havoc among the fish. [Illustration: Fig. 86. The Porpoise.[188]] They are here to-day and gone to-morrow. A few kinds wander up into fresh water, such as the Ganges and the Amazons, but by far the greater number range all over our northern seas, together with their near relations the dolphins, and the bottle-nosed whales, and the strange narwhal, with its two solitary eye teeth, one only of which grows out as a long tusk. All these roam freely through the vast ocean home, coming into the still bays to bring up their young ones, which they nurse and suckle tenderly, afterwards moving off again in shoals to the open sea. There they will follow the ships, and sport and play, and probably we shall never know exactly where their wanderings extend, though it seems that they prefer the northern hemisphere. Among all the dolphin family the most voracious and bloodthirsty is the Grampus or Orca,[189] which is commonly called the “Killer Whale,” because it alone feeds on warm-blooded animals, seizing the seals with its strong, sharp, conical teeth, devouring even its own relations the porpoises, and attacking and tearing to pieces the larger whales. No lion or tiger could be more ruthless in its attacks than this large-toothed whale, which is sometimes as much as twenty-five feet long and has broad flippers. In vain even the mother walruses try to save their young ones by carrying them on their backs; the cunning Orca swims below her, and coming up with a jerk shakes the young one from its place of safety and swallows it in a moment. Nor do they merely fight single-handed, for many voyagers have seen them attack large whales in a pack like wolves, and in 1858 Mr. Scammon saw three killer whales fall upon a huge Californian Gray Whale and her young one, though even the baby whale was three times their size. They bit, they tore, and wounded them both till they sank, and the conquerors appeared with huge pieces of flesh in their mouths, as they devoured their prey. How much they can eat is shown by one orca having been killed which had the remains of thirteen porpoises and fourteen seals in its stomach!