The hippo's yawn is not a sign of sleepiness or boredom but is actually a threat gesture, displaying long, thick, razor-sharp canine teeth, or tusks, with which it is capable of biting a small boat in half. Being fearlessly protective of their turf and young, hippos have killed more than 400 people in Africa - more than any other wild animal. Hippopotamus amphibious means "river horse." The hippo, weighing 1 800 kg (4,000 pounds) and more, lives in Africa, south of the Sahara and along the length of the Nile river, although its range once included Asia and large parts of Europe. Hippos prefer rivers with deep water and nearby reed beds and grasslands, but are also found in salt-water areas near river mouths, and in lakes in Central Africa. They are hoofed vegetarians, feeding on grass, fallen fruit, and occasionally on cultivated crops such as sugar cane or corn during the night. They spend most of the day in the water. The hippo is the third biggest land animals, slightly smaller but heavier than a white rhino (the elephant is the biggest). In spite of its huge size - 3 metres (12 feet) in length, 1,5 metres (five feet) tall, with a mouth measuring a half metre (two feet) across - the hippopotamus can outrun a human. The bellowing of a bull hippo measures an ear-splitting 115 decibels, sounding like the roar of a lion. Nearly all of the famous African explorers and hunters - Livingstone, Stanley, Burton, Selous, Speke, DuChaillu - had boating mishaps with hippos. All considered the hippo to be a wantonlymalicious beast. Spencer Tyron, a hunter, was killed while hunting near the shores of Lake Rukwa, Tanzania. A bull hippo turned over the dugout canoe from which Tyron was shooting, and bit off his head and shoulders. Recent DNA evidence suggests that the hippopotamus is more closely related to cetaceans (whales and dolphins) than it is to any other artiodactyl (even-toed hoofed mammal). 犬齒 獠牙     兩棲的           白犀牛 咆哮 不懷好意的,惡意的   偶蹄動物