The Sword-fish and Thresher Shark also help to destroy this harmless giant of the deep. The Sword-fish pierces it with his pointed "beak"; the other slashes the sides of the wretched Whale with its long tail. It is said, by those who have seen such a fight, that the Thresher's tail cuts deep into the Whale's sides. [Illustration: THE SUCKING FISH] In all parts of the wide sea there are Whales of one kind or another. We have looked briefly at the Sperm and Greenland Whales, and the Killer Whale. Besides these there is the Narwhal, or Sea-unicorn, with a wonderful tusk, which is really a big tooth, some six feet long. Another one, the Bottle-nose Whale, has a long, narrow "beak," and is sometimes washed up on our shores. The Pilot Whale is also seen in herds in our seas. Another visitor, the Rorqual, is not welcomed by the fishermen. This big fellow follows the shoals of Mackerel and Herring. He lives on them, swallowing as many at each gulp as would fill several big baskets. The fishermen can spare him the fish. But it is another matter when he swims through valuable nets, tearing through them as if they were so much cobweb. The commonest Whale of our seas is that small one, the Common Dolphin, who is a midget some five or six feet long. You may have seen Dolphins, for they swim near the surface, and may often be noticed not far from the shore. Like the Rorquals, they follow the Herring and Mackerel shoals. Now and again they dash into the nets, and are shown in the fish-market. EXERCISES 1. Describe how the Whale breathes. 2. What food do the Sperm and Greenland Whales eat? 3. How does the Greenland Whale eat its food? 4, Give the names of five kinds of Whale. LESSON VII TIGERS OF THE SEA [Illustration: A CORAL REEF.] The monsters of the Shark family, fortunately for us, live in warm seas, and so are not often found near the shores of Great Britain. But our seas contain smaller Sharks of various kinds, and in greater number than most people imagine. Sharks are fierce hunters. Many a poor sailor or diver has been torn to pieces and devoured by these ravenous tigers of the deep. Some Sharks are of great size and immense power; they are by far the largest of all living fish; and no animal in the whole kingdom of animals owns such a terrible death-trap of a mouth as the Shark. It is, in some kinds of Shark, armed with seven rows of teeth with keen edges and points! Sometimes a Shark follows a steamer in the open sea, day after day, waiting for whatever may chance his way; and it is astonishing what strange objects he will swallow. These monsters are often caught on a hook baited with a lump of meat, and are hauled to the steamer's deck. One Shark was found to contain all the rubbish that had been pitched overboard; tin cans, a bundle of old coats, a piece of rope, old bones, and so on. What a fierce hunger must have driven the Shark to swallow such a meal as that!