Types of mammals, their characteristics and examples

If I ask you “tell me the first animal that comes to mind”, you have most likely thought of a mammal. And it is that even having a small number of species, it is one of the groups of living beings with the most diversity, and probably because we, human beings, belong to this category and it is one of the most studied. But exactly what are mammals?

What are mammals and their characteristics

Mammals are warm-blooded vertebrate animals , characterized by having mammary glands, with which they produce milk to feed their young. There are about 5,486 species of mammals and, according to the classification of mammals , they are divided into placentals (the majority), marsupials and monotremes.

All mammals descend from a common Triassic ancestor, dating back 200 million years. Because of this, there is a whole series of characteristics of common mammals , such as:

  • The fact that they have mammary glands that make milk, from which they derive their name.
  • Another distinctive fact is that all mammals have hair, at least at some stage in their life.
  • In addition, their bone structure shares certain distinctive characteristics: for example, they all have 7 vertebrae in the cervical part of their spine and, in most cases, with the exception of monotremes, their middle ear is made up of 3 bones (anvil , stirrup and hammer).

Types of mammals

What are the types of mammals? As we have commented previously, there are 3 large families of mammals: placentals, marsupials and monotremes. In turn, these are divided between aquatic mammals , land mammals and flying mammals . There are also other ways to classify mammals, such as their diet: herbivores , carnivores and omnivores . However, here we will focus on the three large groups mentioned at the beginning:

Placental mammals

Placentals are viviparous mammals where the embryo develops within a placenta within the womb for a considerable time. This group presents the largest variety of species, having colonized a great diversity of natural habitats. This is due to a great variety of evolutionary strategies developed: some species have adapted to underwater life (such as whales, dolphins, etc.). Others have adapted to life on land, colonizing jungles, deserts, tundras, savannas and even the subsoil (such as orangutans, camels, elephants and moles). And others, on the other hand, have developed the ability to fly, like bats. This great adaptability explains its evolutionary success, having practically colonized the surface of the planet.

Here you can see more details and examples of placental mammals, if you want to know better what placental mammals are, their characteristics, classification and examples .

Marsupial mammals

In the second group of marsupials the embryo develops mainly in the marsupial bag, after a short period in the mother’s uterus. Comparatively, there are about 5,200 species of placentals for 270 species of marsupials. For the most part, they inhabit the Australian continent, although there are also species in America. Some examples of marsupial mammals are the koala, kangaroos, etc.

Learn more about What are marsupial animals and examples with this other article.

monotreme mammals

The third and last type, the monotremes, are the smallest group (with only 5 species) and with more primitive characteristics of mammals. The reproduction of mammals of this type is based on laying eggs, so for a long time it was in question whether they were really mammals or reptiles. Currently, they only inhabit Australia (and nearby islands). Examples of monotreme mammals are the platypus and different types of echidnas.

Examples of mammals

Here are some examples of mammalian animals :

  • The blue whale ( Balaenoptera musculus ) is a marine mammal that inhabits the oceans. It can reach 30 meters in length and 170 tons in weight, making it the largest animal in history to date. The diet of the mammals of the whale group is mainly krill, and due to their size, they do not have any known predators. We recommend you read this other article on Why the blue whale is in danger of extinction .
  • The Bengal tiger ( Phantera tigris tigris ) is a mammal that inhabits tropical forests and savannas in India, Burma, Nepal and Blangladesh. They can measure 3 meters and weigh about 250 kg, being one of the largest felines. It is a carnivorous hunter animal that is at the top of the trophic chain of its region, feeding on buffalo, monkeys, wild boar, deer, birds, etc. Rarely, they have also attacked man, due to pressure on their habitat. Here you can learn more about why the Bengal tiger is in danger of extinction .
  • The African elephant ( Loxodonta africana ) is the largest living land mammal today, weighing between 6 and 10 tons. Its habitat is restricted to the African continent, and it is characterized mainly by its trunk, tusks and large ears. African elephants mainly feed on tree leaves, grass, and bushes.
  • The brown rat ( Rattus norvegicus ) is one of the most abundant mammals in the world, coming to be considered a pest in some areas. It is an omnivorous rodent, a few cm long, that has colonized all continents, capable of having between seven and eight litters per year of about 12 young.
  • The common bat ( Pipistrellus pipistrellus ) is a species of bat that lives mainly in Europe, Asia and North Africa. Weighing around 5 grams, it feeds on insects at night, which it echolocates, generally near artificial lights. It is one of the mammals capable of flight.
  • The mountain gorilla ( Gorilla beringei beringei ) is a primate that inhabits various reserves in central Africa. It is one of the critically endangered mammals, with only fewer than 900 individuals.
  • The koala ( Phascolarctos cinereus ) is an endemic marsupial to Australia. They feed mainly on eucalyptus leaves, so they mainly live in forests of these trees. They are known to sleep around 20 hours a day.
  • The jackfruit ( Thylamys elegans ) is an endemic marsupial to Chile. It feeds mainly on insects and small vertebrates, although part of its diet is also made up of seeds. Normally, it has nocturnal habits.
  • The platypus ( Ornithorhynchus anatinus ) is a monotreme that inhabits rivers in eastern Australia. It stands out for its duck beak, its beaver tail, and the fact that it is one of the few poisonous mammals that exist. In addition, it can detect its prey by locating the electric fields they generate. It feeds mainly on worms, insect larvae, and small crabs.
  • The Australian echidna ( Tachyglossus aculeatus ) is a monotreme that inhabits Australia, Tasmania, and some parts of New Guinea. As explained above, they are one of the only species of mammals, along with the platypus, that lay eggs. They are covered with spikes, and are similar to hedgehogs. They feed mainly on ants and termites.

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