Hippos are the third largest land mammal after the elephant and the rhinoceros. Weighing in at 1,500–1,800 kg (3,300–4,000 lb), an adult male stands up to 1.5m (4.5 feet) at the shoulder, and, oddly enough, their closest living relatives are whales and dolphins. Hippos spend most of their days submerged in water to keep cool, as they have no sweat glands. Though they have webbed feet, their huge bulk prevents them from floating and they cannot swim. Their size does…