We explain what mammals are, in what habitat they are found and what their structure is like. In addition, its characteristics, reproduction and more.

What are mammals?

Mammals are a class of vertebrate animals that possess milk-producing mammary glands to feed their young . There are about 5,487 species of mammals, of which 5,209 are placental mammals, 272 are marsupials and 5 are monotremes.

Mammalian species tend to take care of their young after they are born long enough for them to be able to fend for themselves, although the time of parental care varies from species to species.

Mammals are homeothermic, that is, "warm-blooded" animals that can self-regulate their body temperature and keep it constant regardless of the temperature of the environment.

Characteristics of mammals :

  1. Habitat

Mammals inhabit all kinds of habitats along the earth's surface , from plains, forests, and mountains to rainforests , deserts, and polar regions.

  1. Homeotherms


Mammals are homeothermic, that is, "warm-blooded" animals that can self-regulate their body temperature and keep it constant regardless of the temperature of the environment. All mammals have a complete, closed, double circulatory system , with a heart divided into four chambers.

  1. Viviparous

The vast majority of mammals are viviparous animals, that is, after fertilization, the embryo develops inside the female's womb , where it receives food and oxygen until the moment of delivery.

The only exceptions are monotremes (the platypus and echidna) , which lay eggs, and marsupials, whose young do not develop in a placenta and must continue to develop in an outer pouch on the female's body at birth.

  1. Lung breathing

Lung breathing

Mammals breathe oxygen thanks to two lungs located in the thoracic cavity . In the case of aquatic mammals (such as dolphins and whales ), animals can submerge for long periods of time but must necessarily surface to breathe, since they can only capture oxygen from the air and not from the water (such as make the fish ).

  1. Bone structure

All mammals have a bony structure made of bone (skeleton) that ends in a skull at the front end , where the brain is housed , and with a spinal column within which is the spinal cord .

  1. Advanced nervous system

Mammals have a highly developed central nervous system that allows them to respond to environmental stimuli by processing information , which implies that mammals can have highly complex and sophisticated behaviors.

  1. Anatomy


All mammals have certain common anatomical and physiological characteristics, such as having a single dental bone contained in the jaw ; a joint between the jaw and the skull; and an auditory system made up of three bones (hammer, anvil, and stirrup). The vast majority of mammals have hair, lips, and teeth.

  1. Extremities

The limbs of mammals have evolved over millions of years to adapt to the environment where the animal lives. In the case of terrestrial animals, the extremities end in legs , which can have hooves, claws, hooves or nails depending on the characteristics of the animal.

In the cases of aquatic mammals (seals, killer whales) the limbs end in hydrodynamic fins , while in flying mammals (bats) they end in membranous wings. Giraffes have evolved over the ages, lengthening their necks to reach the leaves of tall plants , with which they ensure food .

  1. Excretory system separate from the genital

Excretory system separate from the genital

Mammals do not have a cloaca (like birds ), since the excretory system is separate from the genital tract. In addition, all mammals have a membrane called the diaphragm that separates the digestive from the respiratory system .

  1. Parental care

Mammalian species tend to take care of their young after they are born long enough for them to be able to fend for themselves, although the time of parental care varies from species to species . Females have mammary glands, through which they secrete milk with which they feed their young in the first stage of growth.

The above content published at Collaborative Research Group is for informational and educational purposes only and has been developed by referring reliable sources and recommendations from experts. We do not have any contact with official entities nor do we intend to replace the information that they emit.


MA student of the TransAtlantic Masters program at UNC-Chapel Hill. Political Science with a focus on European Studies. Expressed ideas are open to revision. He not only covers Technical articles but also has skills in the fields of SEO, graphics, web development and coding. .

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