Mammals are animals vertebrates, belonging to class Mammalia,that stand out for the presence of by the and for production of milk. Currently there are more than 5,300 species of mammals known, being the human being one of them.
Read too: animal feed
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 body, which is an important feature, together with the layer of fat below the skin, for heating the animal's organism. However, the hairs do not only have this function, they are also related to the camouflage and the perception of sensations.
Presence of mammary glands, that is, of 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, being observed the ejection of milk through the skin 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 cavities
Lung respiration, that is, all mammals have lungs. This feature is even observed in aquatic mammals, such as the whale, which need to go to the surface to achieve oxygen. In aquatic mammals, a relatively large capacity to store oxygen is observed.
System urinary formed by kidneys, ureters, urinary bladder and urethra.
Nervous system with brain well developed.
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 the flesh of their prey. In other vertebrates, dentition 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, meaning they maintain a constant body temperature.
Read too: Are there immortal beings?
classification of mammals
Mammals can be Classifiedin three groups: monotremes, marsupials and eutherians. See more features of each:
Monotremes: they are animals that have the ability to lay eggs as a distinguishing feature. Despite this peculiarity, they also initially feed their young 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, with the echidna and platypus being their representatives.
Marsupials: they are animals that stand out for the way their offspring 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 marsupium, a kind of pouch. Possums and kangaroos are examples of marsupials.
Eutheriums: they are 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 mother and offspring. Unlike marsupials, the development of these mammals is completely completed inside the uterus. Humans, dogs, cats, monkeys, whales, oxen, deer, zebras, armadillos and elephants are examples of eutheriums.
Read too: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. See some examples:
50 examples of mammals |
|
Read too: Differences between seals, sea lions and walruses
Summary about mammals
There are more than 5,300 species of mammals.
Mammals are animals that have hairs and mammary glands.
Mammals have closed circulation; heart with four cavities; urinary system with kidneys and bladder; digestive system formed by a alimentary canal and associated glands; developed brain; and breathe through lungs.
Mammals are classified into three groups: monotremes, marsupials and eutheriums.
Platypus and echidna are examples of monotremes.
Opossums and kangaroos are examples of marsupials.
Human, dog and horse are examples of eutheriums.
