Animal locomotion for other modes of locomotion. Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. Some pinnipeds perform a similar behaviour called "sledding". Some animals are specialized for moving on non-horizontal surfaces. One common habitat for such climbing animals is in trees, for example the gibbon is specialized for arboreal movement, traveling rapidly by brachiation. Another case is animals like the snow leopard living on steep rock faces such as are found in mountains. Some light animals are able to climb up smooth sheer surfaces or
Prostitution among animals observed. A study at Yale–New Haven Hospital trains capuchin monkeys to use silver discs as money in order to study their economic behavior. The discs could be exchanged by the monkeys for various treats. During one chaotic incident, a researcher observed what appeared to be a monkey exchanging a disc for sex. The monkey that was paid for sex immediately traded the silver disc for a grape. The researcher took steps to prevent any possibility of coins being traded for sex after his suspicions were aroused. Prostitution among animals A few studies have suggested that prostitution exists among different species