characteristics of mammals

MAMMALS

Mammals are animals that have two striking characteristics: the presence of body hair and mammary glands, which produce milk.

Mammals are vertebrate animals , belonging to the Mammalia class , which stand out for the presence of hair and the production of milk . There are currently more than 5,300 known mammal species, with humans being one of them.

Also read: Feeding animals

Main characteristics of mammals

Mammals have two characteristics that distinguish them from other groups of animals. These are:

• Presence of hair. All mammals have hair on their bodies, which is an important feature, next to the layer of fat below the skin, for heating the animal’s organism. However, hair does not only have this function, it is also related to camouflage and the perception of sensations.
• Presence of mammary glands, that is, milk-producing glands, which is why mammals receive this name. All females of all mammal species have the ability to produce milk and breastfeed their young. A curious fact is that, despite having mammary glands, not all mammals have nipples, with the ejection of milk through the skin being observed in some species.

In addition to these characteristics, others can be observed in this group, but they are not exclusive to the class, such as:

• Circulation closed, double circulation and heart with four chambers
• Lung breathing, that is, all mammals have lungs . This characteristic is observed even in aquatic mammals, such as the whale, which must go to the surface to obtain oxygen . In aquatic mammals, there is a relatively large capacity to store oxygen.
• Urinary system formed by kidneys, ureters, urinary bladder and urethra.
• Nervous system with well-developed brain .
• Digestive system formed by a alimentary canal and several accessory glands. An interesting fact is that mammals have teeth adapted to process different types of food. Carnivorous mammals, for example, have well-developed canines to help cut prey meat. In other vertebrates, teething is usually less specialized.
• Presence of separate sexes, that is, males and females of each species are observed.
• Internal fertilization.
• Endorthermia . Mammals are endothermic animals, that is, they maintain a constant body temperature.

Despite being aquatic animals, whales, like other mammals, breathe through their lungs.

Also read: Are there immortal beings?

Classification of mammals

Mammals can be classified into three groups: monotremes, marsupials and eutherians. See more features of each:

• Monotremes: theseare animals that have the capacity to lay eggs as a striking feature. Despite this peculiarity, they also feed their young, initially, with milk, which is sucked directly from the mother’s skin, since these animals do not have nipples. Monotremes are found in Australia and New Guinea, the echidna and the platypus being their representatives.

The platypus is a monotreme.

• Marsupials: theyare animals that stand out for the way their puppies develop. In this group of mammals, it is observed that the embryo develops inside the uterus, but it is born very early and completes its development inside the baby carrier, a kind of pouch. Opossums and kangaroos are examples of marsupials.

The kangaroo is a marsupial.

• Euteriums: theyare mammals that stand out for the presence of complex placentas. The placenta is an organ that appears during pregnancy and has, among others, the function of ensuring the exchange of nutrients between the mother and the baby. Unlike marsupials, the development of these mammals is completed entirely inside the uterus. Human beings, dogs, cats, monkeys, whales, oxen, deer, zebras, armadillos and elephants are examples of eutherians.

The monkey is a euterium.

Also read: Differences between humans and other animals

Examples of mammalian animals

We know that there are more than 5,300 species of mammals, and many of these are known to us. Here are some examples:

Polar bear is an example of a mammal.

Also read: Differences between seals, sea lions and walruses

Summary about mammals

• There are more than 5,300 species of mammals.
• Mammals are animals that have hair and mammary glands.
• Mammals have closed circulation; heart with four cavities; urinary system with kidneys and bladder; digestive system formed by an alimentary canal and associated glands; developed brain; and breathe through lungs.
• Mammals are classified into three groups: monotremes, marsupials and eutherians.
• Platypus and echidna are examples of monotremes.
• Opossums and kangaroos are examples of marsupials.
• Human beings, dogs and horses are examples of eutheria.