Facts About Mammals

You are a mammal. I am a mammal. All mammals are warm-blooded and even though you probably know someone you swear is a reptile, I can assure you he is a mammal. So what makes a mammal a mammal? All mammals are warm-blooded, have hair or fur, have three middle ear bones, have mammary glands, are vertebrates (have a skeletal system inside the body), breathe air, and have a neocortex (a region of the brain). The most intelligent animals on Earth are mammals, including humans, elephants, other primates and some cetaceans (commonly known as whales, dolphins and porpoises).

Humpback whale (Megaptera novaeangliae).
Humpback whale (Megaptera novaeangliae).

The biggest animal

The largest animals on Earth, whales, are mammals. The Blue whale can reach a staggering one hundred and ten feet or thirty-three point six meters in length. The smallest mammal, the Bumblebee bat is a mere thirty millimeters or one inch. Humans depending upon where they live, fall somewhere between the Blue whale and the Bumblebee bat.

Land and aquatic mammals

The basic body design of mammals consists of four legs for most land mammals. A primate, who is what we humans are, can also walk upon two legs. Although most mammals are land-borne, there are many mammals that have adapted to an aquatic life and live in or mostly in water. Some of these aquatic dwellers include whales, seals, otters and manatees.

How we got the name Mammal?

The word mammal is the modern name shortened from the scientific name, Mammalia coined by Carl Linnaeus in 1758. The main thing that sets mammals apart from other animals are mammary glands. Mammary glands, you know them as breasts on women, are where mammals produce milk to nurse their young. Most mammals also give birth to live young, unlike most of the other animals that populate our planet. However, there are five species of monotremes, which actually lay eggs and they include the platypus and four species of spiny anteaters; all of which live in Australia and New Guinea.


All mammals reproduce when the male of any given species mates through sexual reproduction with the female of the same species. Different mammal species have different social behaviors. For example, most cats are solitary by nature, only coming together to mate. Other mammals live in social groups ranging from a few individuals to hundreds. All mammals, after mating, care for their young until they are able to care for themselves. In social groups, mammals tend to share in the caring for the young and it is not unusual for another member of the group to take on caring for a baby that has been separated from its mother. Although, over the last two hundred years or so, humans have begun to form smaller groups such as the nuclear family, we have for most of our history lived in larger group settings such as tribes.

Mammals are pretty young

In geological time, mammals are a fairly recent addition to nature. However, since the first mammals appeared millions of years ago, they have evolved to become human beings and have had more of an impact on our world than any other known species.

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