Beasts have a lot of species and quite different shapes. Beasts living on land and feeding on vegetations are always evolving towards the direction of running quickly. They have thinner and longer legs and they can gallop at a fantastic speed for quite a long time, such as wild horses and antelopes. Other species of beasts evolve towards the direction to grow larger bodies, such as elephants, rhinoceros and buffaloes. Whales and dolphins, which adapt themselves to live in water, have changed their shapes into something like a fish. Their fore limbs and tails have changed into fins and their hind limbs have become vestigial and disappeared. Amphibians such as seals, sea dogs and beavers change into torpedo-like shapes. They have webs in-between their toes, which can help them to arm pull. Beasts that are good at burrowing caves such as moles and bamboo rats change their bodies into cylindrical. Their eyes and ears are vestigial and they can only act very slowly. Primates living in the trees not only have flexible limbs, but also well-developed tails in some species. Their tails can help them to keep balance or to grasp branches of the trees during their traveling among trees. Flying squirrels have skin membranes in-between their limbs and they can glide if necessary. The fore limbs of bats change into wings and they become beasts that can really fly.
