Sloths
The slow-moving sloth is a nocturnal, tree-dwelling mammal that inhabits the rain forests of South America. The diet of sloths is primarily leaves, though they occasionally nibble on fruit. Because of their low-calorie diet, sloths conserve energy by sleeping up to 15 hours a day.
Ungulates
Many hoofed animals, known as ungulates, are herbivores. Among these are ruminants, even-toed ungulates with compartmentalized stomachs that allow them to swallow vegetation and later regurgitate it as cud and chew it. Examples of ruminants are giraffes, which feed primarily on acacia leaves, and camels, which subsist on dry desert vegetation. Cattle, guanacos and deer are also ruminants. Hippopotamuses are not ruminants, but like many other even-toed ungulates, they are herbivores. They feed primarily on wetland grasses. Several odd-toed ungulates, such as rhinoceroses, tapirs and horses, are also primary consumers.
Marsupials
A number of marsupials -- species in which offspring develop inside external pouches on females -- are herbivores. The largest marsupial, the kangaroo, consumes mostly grasses. Wallabies, which are closely related to kangaroos, are also herbivores, as are wombats. Koala bears -- which are not bears at all, but marsupials -- feed on the leaves of eucalyptus trees.
Primates
Though most primates consume both plant and animal matter, some are strict herbivores. The gelada baboon of Ethiopia, for instance, is the only primate that feeds primarily on grasses. The majority of lemurs, a type of primate endemic to Madagascar, are also herbivores. Though gorillas, mangabeys and howler monkeys occasionally eat insects, their diet is mainly vegetation.
Rodents
Herbivorous rodents include the agouti, a small mammal in the rain forests of Central and northern South America. Its diet includes mainly fallen fruits and nuts. According to the San Diego Zoo, the agouti can sense when fruit hits the ground and is the only animal capable of prying open a Brazilian nut. The agouti is closely related to the acouchi, a generalist herbivore that occurs in Colombia, Ecuador, Peru and Brazil. Beavers and capybaras, the world's largest rodents, are also herbivores.
Elephants
Although elephants, the largest of all land animals, subsist entirely on vegetation, they have varied diets that include grass, fruit, leaves and even bark. Elephants consume between 300 and 400 pounds of plant matter a day and have been known to eat crops such as banana and sugarcane.
Aquatic Mammals
Manatees and dugongs, which make up the order sirenia, are herbivores found in tropical and sub-tropical coastal waters and rivers. Though they are known collectively as sea cows, manatees and dugongs are most closely related to elephants. They feed on sea grasses and weeds.