Courses
Courses for Kids
Free study material
Offline Centres
More

Mammalia

share icon
share icon

Mammalia Diversity in Living Organisms

IVSAT 2024

All the animals relating to class Mammalia are termed as mammals. In the animal kingdom, one of the most developed species are mammals that are categorized under Vertebrata. Around 6,000 species of living mammals are present on the planet. They are well adapted to their surroundings such as from deserts, oceans, and polar regions to rivers and rainforests, etc because of their distribution all over the world They are depicted by the presence of mammary glands which helps them to feed their offsprings.

 

(Image will be Uploaded Soon)

 

Main Characteristics of Mammals

Below is the list of characteristics of class Mammalia:

  • Sweat glands and oil glands are found on the skin.

  • Presence of mammary glands, which aid in the production of milk to feed their young.

  • All these animals are warm-blooded.

  • Their hearts are divided into four chambers.

  • The tooth comes twice in these animals (Diphyodont).

  • No nucleus is found in its red blood cells (except in camels and llama). 

  • The skin of mammals has hair.

  • External ear (pinna) is present in mammals.


  • They are of different types - heterodont and thecodont. 


  • The skull's form is dicondylic.


  • A four-chambered heart is found in mammals. Both the renal portal and sinus venous systems are absent.

  • They possess muscular diaphragms.

  • They respire through lungs.


Classification of Mammals


(Image will be Uploaded Soon)


The largest class in the animal kingdom is Mammalia. Several types of mammals are there which can be differentiated up into smaller mammals, larger mammals, and marine mammals, etc. On the basis of their reproduction, they are classified into  2 subclasses. 

  • Prototheria

  • Theria

 

Subclass Prototheria

Prototherians are considered as the most primitive mammals and they are only restricted to Australia and its adjacent islands such as Tasmania and New Guinea. Prototheria is also named as Monotremes. This subclass includes egg-laying mammals. Prototheria includes one order that comprises 6 species. 

 

Order:  Monotremata

 

Example: Duck Billed platypus (Ornithorhyncus), Echidna (Tachyglossus).

 

Subclass Theria

The members of this subclass give birth to young ones. It is divided into 2 infraclasses - 

  1. Metatheria

  2. Eutheria

 

1. Infraclass Metatheria

The females of this infraclass possess a marsupium or brood pouch and are thus known as marsupials or pouched mammals. Immature young are born to the mammals in this infraclass and remain in their mother's pouch until they reach adulthood. There are approximately more than 250 species in this infraclass and they are inhabited throughout Australia, Papua New Guinea and some parts of America. 

 

For example, kangaroos, koalas and possums.

 

Metatheria Sub-class is Divided into 7 Orders Including 250 Species.

 

Order

Examples

Notoryctemorphia

Marsupial moles

Diprotodontia

Koalas, kangaroos

Microbiotheria

Colocolo opossum

Dasyuromorphia

Dasyurids, thylacines

Paucituberculata

South American rat opossum

Peramelemorphia

Bandicoots

Didelphimorphia

New world opossum


2. Infraclass Eutheria

Mammals that give birth to well developed young ones or the child directly belong to this infraclass. An embryo is formed by the young ones in their mother's stomach where they grow for a particular period of time. They derive nutrition for their growth and development from the placenta of the mother. This infraclass comprises 19 orders.

 

The orders of this infraclass are listed below-

 

S.No.

Order

Examples 

1.

Insectivora

Moles, shrews

2.

Dermoptera

Flying lemurs

3.

Proboscidea

Elephant 

4.

Rodentia

Hamsters, squirrel, rats

5.

Artiodactyla

Goat, giraffes, camels

6.

Carnivora

Dogs, Bears

7.

Chiroptera

Bats, flying foxes

8.

Pholiodota

Pangolins

9.

Lagomorpha

Rabbits and hares

10.

Cetacea

Whales, dolphins

11.

Sirenia

Seacows

12.

Perissodactyla

Horses, Zebras

13.

Edentata

Armadillos

14.

Primates

Lemurs, lorises

15.

Afrosoricida

Golden moles

16.

Hyracoidea

Hyraxes

17.

Pilosa

Sloths

18.

Scandentia

Tree shrews

 

Characteristics of Mammals


(Image will be Uploaded Soon)

 

Appendages:

  • 2 pairs of pentadactyl limbs are present. In this, each foot has either 5 or fewer toes given with horny nails, claws or hooves.

  • They are adapted variously for running, jumping, swimming, climbing, etc.

 

Digestive System:

  • Relatively smallmouth with movable lips.

  • True salivary glands present in the buccal cavity.

  • Different types of teeth are attained by them (Heterodont).

 

Respiratory System:

  • They breathe only through the lungs which are elastic and spongy.

  • In breathing, both the rib muscles and diaphragm play a vital role for the purpose of respiration.

 

Circulatory System

  • The circulatory system of mammals is closed.

  • The heart pumps oxygenated blood which is transported to the several parts of the body.

  • The hepatic portal system is present while the renal portal system is not.

  • In most mammalian species, RBCs are concave, circular, and non-nucleated.

 

Excretory System:

  • A pair of bean-shaped kidneys are found which are metanephric.

  • They are ureotelic animals (excrete urea).

 

Sense Organ: 

  • With the help of internal nasal passages, the olfactory sacs open far back into the pharynx.

  • Movable lids are present in their eyes.

  • An organ of Corti is present in the internal ear and 3 bony ear ossicles (malleus, incus, and stapes) are present in the middle ear.

 

Fun Facts of Mammalia

  • In a mammal, the highest body temperature is of a goat (Average 39°Celsius).

  • Echidna and Duck-billed Platypus are the egg-laying mammals.

  • Atlantis of mammalian embryos help in the purpose of respiration.

  • Excretion in hemichordates takes place by the glomerulus.

  • The smallest man like Ape is an Orangutan.

Want to read offline? download full PDF here
Download full PDF
Is this page helpful?
like-imagedislike-image

FAQs on Mammalia

1. What are the Main Orders of Placental Mammals?

  • Artiodactyls:  These mammals have even a number of fingers in paws or claws like giraffes.

  • Perissodactyls: They are named as ungulates (hooved). These mammals are large in size having an odd number of fingers on each paw-like rhinos.

  • Carnivorous:  Include predators with canine teeth like lions.

  • Cetaceans: Mammals are aquatic which lack posterior limbs like whales.

  • Edentates:  Mammals with rare or no teeth like anteaters.

  • Lagomorphs: Mammals are small in size with continuously growing 3 pairs of incisors teeth specialized in gnawing like rabbits.

  • Primates: Characterized by a well-developed brain and large cranium includes humans.

2. What are the Key Characteristics of Mammals on the Basis of their Reproductive System?

  • In the adults of a male adult, testes usually descend into scrotal sacs.

  • The penis is a copulatory organ found in males.

  • Internal fertilization takes place.  Gonoducts head directly to the exterior areas.

  • Mostly viviparous animals are found that give birth directly to the young ones.

  • In the female's uterus development occurs. The embryo has amnion, chorion, and allantois.

  • For the purpose of nourishment, excretion, and respiration, the fetus is fixed by the placenta into the uterine wall.

  • After the birth of young ones, they are nourished with milk for some time.

3. What are the Main Orders of Placental Mammals?

Artiodactyls:  These mammals have even a number of fingers in paws or claws like giraffes.

  • Perissodactyls: They are named as ungulates (hooved). These mammals are large in size having an odd number of fingers on each paw-like rhinos.

  • Carnivorous:  Include predators with canine teeth like lions.

  • Cetaceans: Mammals are aquatic which lack posterior limbs like whales.

  • Edentates:  Mammals with rare or no teeth like anteaters.

  • Lagomorphs: Mammals are small in size with continuously growing 3 pairs of incisors teeth specialized in gnawing like rabbits.

  • Primates: Characterized by a well-developed brain and large cranium includes humans.


Competitive Exams after 12th Science