10 characteristics of MAMMALS

The mammals They are incredibly diverse animals: they live in almost every available habitat on earth (including deep seas, rainforests, and deserts), and range in size from one-ounce shrews to 200-ton whales. What exactly is it that makes a mammal a mammal, and not a reptile, a bird or a fish? In this article, you'll learn about the eight main features of mammals, ranging from hair to four-chambered hearts.

mammalian characteristics

Important Features of Mammals



  1. hair and skin: All mammals have hairs that grow on some parts of their bodies during at least some stages of their life cycles. Mammalian hair can take several different forms, including thick fur, long whiskers, defensive feathers, and even horns. Hair serves a variety of functions: insulation against the cold, protection for delicate skin, camouflage against predators (such as zebras and giraffes), and sensory feedback (as evidenced by your house cat's sensitive whiskers). In general, the presence of hair goes hand in hand with a warm-blooded metabolism. What about mammals that don't have visible body hair, like whales or Olympic swimmers? In the case of whales and dolphins, many species have sparse amounts of hair during the early stages of their development, while others retain faint patches of hair on their chins or upper lip. And of course, even completely hairless-looking humans still retain hair follicles in their skin.
  2. Mammary glands: Unlike other vertebrates, mammals nurse their young with milk produced by the mammary glands. Although present in both males and females, in most mammalian species the mammary glands are only fully developed in females, hence the presence of smaller nipples in males (including humans). The exception to this rule is the male Dayak fruit bat, which nature has endowed (for better or worse) with the task of nursing. The mammary glands are modified and enlarged sweat glands consisting of ducts and glandular tissues that secrete milk through the nipples; Milk provides the young with much-needed proteins, sugars, fats, vitamins and salts. However, not all mammals have nipples: monotremes like the platypus, which diverged from other mammals early in evolutionary history, instead secreting the milk produced by their mammary glands through ducts located in their abdomens.
  3. Temperature regulation: While most mammals are warm-blooded, not all are capable of regulating their temperature, which is the definition of warm-blooded. Bats and mole rats cannot regulate their body temperatures; While bees, birds and the hawk moth can.
  4. Single-boned lower jaws: The lower jaw of mammals is made up of a single piece that attaches directly to the skull. This bone is called the dentary, because it retains the teeth of the lower jaw; in other vertebrates, the dentary is only one of several bones in the lower jaw and does not attach directly to the skull. So what's the problem? Well, this one-piece lower jaw and the muscles that control it give mammals a powerful bite, and it also allows them to use their teeth to cut and chew their prey (like wolves and lions), or grind up tough plant matter. (like elephants and gazelles).
  5. Three bones in the middle ear: The three bones of the inner ear: the incus, the malleus, and the stirrup, commonly known as the malleus, incus, and stirrup, are unique to mammals. These tiny bones transmit sound vibrations from the tympanic membrane, or eardrum, to the inner ear, transforming these vibrations into neural impulses that are then processed by the brain. Interestingly, the maleceus and incus of modern mammals evolved from the lower jaw bone of mammals' immediate predecessors, the "mammalian-like reptiles" of the Paleozoic Era, technically known as peptids.


  6. Single tooth replacement: Dhyhyodonty is a pattern, not unique to mammals, in which teeth are replaced only once in a vertebrate's lifetime. The teeth of newborn and young mammals are smaller and weaker than those of adults; This first set, known as the deciduous teeth, falls out before adulthood and is gradually replaced by a larger, more permanent set of teeth. (This fact will be apparent to every first or second grader reading this article!) By the way, animals that continually replace their teeth throughout their lives, such as sharks, are known as polyphodonts.
  7. Warm-blooded metabolisms: Mammals are not the only vertebrates to have endothermic (warm-blooded) metabolisms; This is a trait shared by modern birds and their ancestors, the theropod (meat-eating) dinosaurs of the Mesozoic Era. However, it can be argued that mammals have made better use of their endothermic physiologies than any other order of vertebrates: it's the reason why cheetahs can run so fast, goats can scale mountainsides, and humans they can write books. (As a general rule, cold-blooded animals like reptiles have much slower metabolisms, since they must rely on external weather conditions to maintain their internal body temperatures. Most of them can barely write poetry.)
  8. Diaphragms: As with some of the other traits on this list, mammals aren't the only vertebrates to possess a diaphragm, the muscle in the chest that expands and contracts the lungs. However, mammalian diaphragms are possibly more advanced than those of birds, and definitely more advanced than those of reptiles. What this means is that mammals can breathe and use oxygen more efficiently than these other orders of vertebrates, which, combined with their warm-blooded metabolisms (see above), allow for a wider range of activities and exploitation. most complete of the ecosystems available.
  9. Four-chambered hearts: Like all vertebrates, mammals have muscular hearts that contract repeatedly to pump blood, which distributes oxygen and nutrients throughout the body and removes waste products such as carbon dioxide. However, only mammals and birds possess four-chambered hearts, which are more efficient than the two-chambered hearts of fish and the three-chambered hearts of amphibians and reptiles. A four-chambered heart separates oxygenated blood, which comes from the lungs, from partially deoxygenated blood that circulates to the lungs to be re-oxygenated. This ensures that mammalian tissues only receive oxygen-rich blood, allowing for more sustained physical activity with fewer rest intervals.
  10. Complex functions of the brain: Mammalian brains are larger than other animals. This is particularly true of the cerebellum, the part of the brain that controls memory and learning. Mammalian brains also possess a unique region of the brain called the neocortex. The neocortex functions as the area of ​​the brain that handles sensory perception, motor commands, and spatial reasoning. Conscious thought and human language are also processed in the neocortex.




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ENCICLOPEDIA DE CARACTERÍSTICAS (2023) 10 characteristics of MAMMALS, en 10caracteristicas.com. https://10caracteristicas.com/en/10-characteristics-of-mammals/ (Consultado el: 26-09-2023)

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