Mammals are a group of warm-blooded vertebrate animals and include the largest animals on the planet. They are distinguished from other animals by having hair or fur and mammary glands for milk production in females. Mammal animals evolved on land and are mostly four-legged animals but a number of species have moved back to the sea or evolved to life in the air and in trees.

Mammals are a class of animals that includes a wide range of different species. Most species fall into a group known as placentals. Placental mammals all help their unborn young develop in the womb by supplying food through a placenta.

Placental mammals include animals such as rodents (mice, squirrels), carnivora (cats, dogs, bears), primates (humans, monkeys) and many more. Non-placental mammals belong to a group called marsupials, such as kangaroos and opossums, and they do not feed their developing young via a placenta.

Mammals are considered to be the most intelligent group of organisms on Earth. Humans, in particular, are the epitome of intelligent organisms. Other clever mammal groups include primates, elephants, whales, and dolphins.

Primates | Mammals

Primates are a group that includes apes, humans, lemurs, lorises, monkeys and tarsiers. They have grasping hands and feet with nails rather than claws. Primates are the only mammals found on all seven of Earth’s continents.

Rodents | Mammals

Rodents are a large group of well-known animals such as rats, mice, squirrels, and chipmunks. Rodents have a set of constantly growing front teeth. They must continually gnaw on food and wood to stop their front teeth from growing too long.


Bats have long been the victims of a misguided reputation as unpleasant animals. The vast majority of species feed only on plants and insects and pose no threat to humans or any other large animals. Bats use echolocation to see objects in the dark and are the only mammals with the ability to fly.

Marine mammals

Mammals, which evolved on land, made their way into water some millions of year ago to take advantage of what the sea has to offer. Marine mammals include a range of water-dwelling animals such as seals, walruses, sea otters, whales, dolphins, dugongs, and manatees.


Ungulates are a group of large mammals that are distinguished from other mammals by the presence of hooves. They are an extremely well-known and economically important group that include animals such as horses, cows, goats, deer, pigs plus many more.


Mammals are separated into two distinct evolutionary lines: the marsupials and the placentals.  Marsupials are named after the abdominal pouch, called a ‘marsupium’, in which their young live while they are suckling. Marsupials are quite different to other mammals.


The carnivorans are an amazing group of animals that share a special connection with humans. They are all related by a distant relative who evolved to eat meat. The carnivorans include animals such as cats, dogs, bears, seals, mustelids plus many other well-known animals.

Mammalian skeleton

Mammals have well-developed skeletons and although there is a wide range of differences between mammal species, the main structure of mammalian skeletons follow the same patterns. The skeleton can be separated into the head and body or axial and appendicular skeletons.