Science, Tech, Math › Animals & Nature Mammals: Definition, Photos, and Characteristics Share Flipboard Email Print Animals & Nature Mammals Amphibians Birds Habitat Profiles Reptiles Wildlife Conservation Insects Marine Life Forestry Dinosaurs Evolution View More By Laura Klappenbach Ecology Expert M.S., Applied Ecology, Indiana University Bloomington B.S., Biology and Chemistry, University of Illinois at Urbana-Champaign Laura Klappenbach, M.S., is a science writer specializing in ecology, biology, and wildlife. our editorial process Laura Klappenbach Updated January 02, 2020 Pictures of mammals, including pronghorn, meerkats, lions, koalas, hippopotamuses, Japanese macaques, dolphins and more. 01 of 12 Pronghorn Photo © MyLoupe UIG / iStockphoto. Pronghorn are deer-like mammals that have light-brown fur on their body, a white belly, a white rump, and black markings on their face and neck. Their head and eyes are large and they have a stout body. Males have dark brownish-black horns with anterior prongs. Females have similar horns except that they lack prongs. 02 of 12 Meerkat Photo © Paul Souders / Getty Images. Meerkats are highly social mammals that form packs of between 10 and 30 individuals consisting of several breeding pairs. The individuals in a meerkat pack forage together during daylight hours. While some members of the pack feed, one or more members of the pack stand sentry. 03 of 12 Lion Photo © Keith Levit / Shutterstock. The lion is the second-largest species of cat, smaller than only the tiger. Lions inhabit savanna grasslands, dry savanna forests, and scrub forests. Their largest populations are in eastern and southern Africa, remnants of a vast range that once extended over most of Africa, southern Europe and into Asia. 04 of 12 Koala Photo © Kaspars Grinvalds / Shutterstock. The koala is a marsupial native to Australia. Koalas feed almost exclusively on eucalypt leaves which are low in protein, difficult to digest, and even contain compounds that are toxic to many other animals. This diet means that koalas have a low metabolic rate (like sloths) and as a result spend many hours each day sleeping. 05 of 12 Japanese Macaques Photo © JinYoung Lee / Shutterstock. Japanese macaques (Macaca fuscata) are Old World monkeys that inhabit a variety of forest habitats in Japan. The Japanese macaque lives in groups of between 20 and 100 individuals. Japanese macaques feed on leaves, bark, seeds, roots, fruit and occasionally invertebrates. 06 of 12 Hippopotamus Photo courtesy Shutterstock. The hippopotamus is a large, semiaquatic even-toed ungulate. Hippos live near rivers and lakes in central and southeastern Africa. They have bulky bodies and short legs. They are good swimmers and can remain underwater for five minutes or more. Their nostrils, eyes, and ears sit atop their heads so that they can almost entirely submerge their heads while still being able to see, hear, and breath. 07 of 12 Grey Wolf Photo © Petr Mašek / Shutterstock. The grey wolf is the largest of all canids. Grey wolves usually travel in packs consisting of a male and female and their young. Grey wolves are larger and stronger than their cousins the coyote and the golden jackal. Gray wolves are longer and their paw size is considerably larger. 08 of 12 Fruit Bat Photo © HHakim / iStockphoto. Fruit bats (Megachiroptera), also known as megabats or flying foxes, are a group of bats native to the Old World. They occupy tropical and subtropical regions of Asia, Africa, and Europe. Fruit bats are not capable of echolocation. Fruit bats roost in trees. They feed on fruit and nectar. 09 of 12 Domestic Sheep Photo courtesy Shutterstock. Domestic sheep are even-toed ungulates. Their closest kin includes bison, cattle, water buffalo, gazelles, goats, and antelopes. Sheep were among the first animals to be domesticated by humans. They are raised for their meat, milk, and fleece. 10 of 12 Dolphins Photo © Hiroshi Sato / Shutterstock. Dolphins are a group of marine mammals that includes dolphins and their relatives. Dolphins are the most diverse group of all cetaceans. Dolphins includes a wide variety of species such as bottlenose dolphins, humpbacked dolphins, Irrawaddy dolphins, black dolphins, pilot whales, orcas, and melon-headed whales. 11 of 12 Brown Hare Photo courtesy Shutterstock. The brown hare, also known as the European hare, is the largest of all lagomorphs. The brown hare inhabits northern, central and western Europe. Its range also extends into western Asia. 12 of 12 Black Rhinoceros Photo © Debbie Page Photography / Shutterstock. The black rhinoceros, also known as the hooked-lipped rhinoceros, is one of five living species of rhinos. Despite its name, the skin of the black rhinoceros is not truly black but instead slate grey in color. Skin color can vary depending on the mud in which the black rhino wallows. When covered in dry mud, the black rhinoceros may appear white, light grey, reddish, or black.