Class Mammalia

Mammalia is a class of Kingdom Animalia. The organisms belonging to class Mammalia are called mammals. These are the more advanced organisms in the animal kingdom. The presence of mammary glands is one of the distinguished characteristics of mammals. About 6000 different species of mammals can be found in deserts, seas, polar regions, rivers, and rainforests. They have specific characteristics such as mammary glands to produce milk for their children.

What is Mammalia?

Mammalia is a class within the Animalia Kingdom. Mammals are organisms belonging to the class Mammalia. The mammals have unique characteristics, such as mammary glands for milk, warm-blooded, and different types of teeth. The body parts of all mammals are similar, including the limbs, digestion systems, lungs for breathing, circulatory systems with a heart, kidney excretions, and taste organs. Based on reproduction, mammals are grouped into two subclasses: Prototheria and Theria. The mammals give birth to their children but some mammals lay eggs. Human is also an example of mammals.

Mammalia Examples

A group of vertebrate animals are known as mammals or mammals. A few examples are:

• Cats
• Dogs
• Apes
• Whales
• Dolphins
• Monkeys

Characteristics of Mammals

The distinguishable characteristics make mammals differ from other animals. The characteristics of mammals are as follows:

• Presence of mammary glands that produce milk for the offspring.
• Warm-blooded.
• Most mammals have red blood cells without a nucleus (except for camels and llamas).
• Breathe through lungs.
• Muscular diaphragms.
• Four chambered heart.
• The renal portal and sinus venous systems are absent.
• Diphyodont (two sets of teeth).
• Different types of teeth: heterodont and thecodont.
• Skin is covered in hair.
• Presence of sweat and oil glands on the skin.
• Presence of external ears (pinna).
• Dicondylic Skull.

Types of Mammals

Mammals are broadly classified into three categories:

• Marsupials: Most of the marsupials have pouches and they give birth to poorly developed young ones. Kangaroo is an example.
• Egg-laying Monotremes: They lay eggs with soft shells. Platypus is an egg-laying monotremes.
• Placentals: Humans and whales are examples of Placental Mammals. They give birth to well-developed young ones.

Classification of Mammals

The Mammalia is the largest class in the kingdom Animalia. There are several types of mammals such as small, large, marine mammals, etc. Based on reproduction, mammals are grouped into two subclasses:

Prototheria

The most primitive type of mammal is Prototheria, also known as Monotremes. These are restricted to Australia and near places such as Tasmania and New Guinea. Prototheria are unique due to their egg-laying nature. Monotremata is an order under subclass Protheria that consists of six species.

E.g.: Ornithorhynchus (Duck-Billed Platypus) and Tachyglossus (Echidna)

Theria

It includes animals that give birth to their children. Two infraclasses of this subclass are Metatheria and Eutheria:

Metatheria

Animals belonging to Metatheria are called marsupium marsupials or pouched mammals. The female animals belonging to this infraclass have pouches. The offspring of these mammals are immature and live in their mother’s pouch until adulthood. The infraclass Metathesis is divided into 7 orders as follows:

• Notoryctemorphia
• Diprotodontia
• Microbiotheria
• Dasyuromorphia
• Paucituberculata
• Peramelemorphia
• Didelphimorphia

Metatheria has more than 250 species found in Australia, Papua New Guinea, and some parts of the United States. E.g.: Kangaroos, koalas, etc

Eutheria

Mammals that give birth to the child directly belong to infraclass Eutheria. An embryo formed inside the mother’s stomach is developed as an offspring. These offspring get their nutrition inside the mother’s womb through the placenta. This infraclass is divided into 19 orders.

Orders of Eutheria

The following table lists the orders of Eutheria:

Order	Example
Insectivora	Sorex (Shrew)
Chiroptera	Pteropus (flying fox)
Edentata	Dasypus (Armadillo)
Pholidata	Manis (Pangolin/scaly anteater)
Tubulidentata	Orycteropus (Aardvark/cape anteater)
Rodentia	Rattus (Rat)
Lagomorpha	Oryctolagus (Rabbit)
Cetacea	Delphinus (Dolphin) and Balaenoptera (Blue whale)
Sirenia	Halicore (Dugong)
Carnivora	Panthera tigris (Tiger)
Hyracoidea	Hyrax (Procavia)
Artiodactyla	Bubalus (Water buffalo)
Perissodactyla	Equus (Horse)
Proboscidea	Elephas maximus (Indian elephant)
Primates	Homo sapiens (Human)
Dermoptera	Cynocephalus (flying squirrel)

Features of Mammalia

The following are the features of mammalia:

Limbs

• Two pairs of legs with as few as five toes.
• Have nails, claws, or hooves.
• These limbs are used for different types of activities such as running, swimming, jumping, climbing, etc.

Digestive System

• Slightly smaller mouths.
• Have lips with little movement.
• Presence of heterodont teeth.
• Presence of true salivary gland in the mouth.

Respiratory System

• Elastic and spongy lungs.
• The respiratory system is made up of rib muscles and diaphragms.

Circulatory System

• Closed circulatory system.
• Oxygenated blood is sent from the heart to different parts of the body.
• Presence of hepatic portal.
• Absence of renal portal.
• Red blood cells are concave, circular, and non-nucleated in most mammalian species.

Excretory System

• Presence of a pair of bean-shaped, metanephric kidneys.
• Ureotelic animals (excretes urea).

Sense Organs

• The olfactory sacs open into the pharynx through the internal nasal passages.
• Presence of movable lids in the eyes.
• Presence of three bony ear ossicles (malleus, incus, and stapes) in the middle ear.
• Presence of an organ of Corti in the internal ear.

Some Interesting Facts About Mammals

The below are some of the interesting facts about mammals:

• The goat has the highest body temperature having mammals.
• Embryos of mammals have the “Atlantis” that helps in respiration.
• Echidnas and Duckbilled Platypus are egg-laying mammals.
• Hemichordates excrete through the glomerulus.
• The Orangutans are the smallest apes that look like humans.
• Bat is a flying mammal.

Conclusion – Mammalia

Mammalia is a class of animals in the animal kingdom. Members of this class are called mammals. Mammals have mammary glands to produce milk for their offspring. The class is divided into two infraclasses: Protothera and Theria. In the majority of mammals, they give birth to their children, but some mammals lay eggs. Humans are also mammals.

FAQs on Mammalia

What is Mammalia?

Mammalia is a class of kingdom Animalia that includes warm-blooded vertebrates.

What are Mammals?

Mammals are warm-blooded animals that belong to the class Mammalia. These organisms give birth to their offspring and some lay eggs.

Which is the Largest Mammal in the World?

The African elephant is considered the largest mammal in the world.

What is the Distinguishable Characteristic of Mammalia?

The organisms belonging to class Mammalia have mammary glands and these are warm-blooded.

Is Human Mammal?

Yes, humans belong to the class Mammalia. They are warm-blooded animals with the presence of mammary glands.