Mammals

Mammals are warm-blooded vertebrates that have four limbs, hairs, and complex brains. They also have mammary glands that produce milk to feed their young. Mammals can be classified into three groups: egg-laying monotremes, marsupials, and placentals. Some examples of mammals include Humans, Dogs, Cats, Whales, Dolphins, Bats, and Elephants. In this article, we will discuss mammals and how they are classified based on their characteristics with some of the examples.

What are Mammals?

Definition of Mammals: Mammals are warm-blooded vertebrates that have backbones, hair or fur, mammary glands, and the ability to give birth to live young.

Mammals are animals that fall under the class Mammalia. They are among the most evolved species in the animal kingdom and are classified as vertebrata. They are distinct from all other animals due to their advanced features. They are characterised by hair, mammary glands for nurturing young with milk, a diaphragm, three middle ear bones, and a lower jaw consisting of a single pair of bones that articulate uniquely with the skull.

Their mammary glands, which they use to nurse their young, are what distinguish them. They can be found all over the world and have adapted well to their environment, which includes rivers, rainforests, polar regions, deserts, and oceans. Mammals can regulate their body temperatures and internal environment in extreme heat and dryness, as well as in severe cold. This versatility in surviving and thriving on Earth is largely attributed to their unique ability. The world is home to about 6,000 different species of living mammals.

Also Read: Levels of Organization in Animals

Characteristics of Mammals

Characterisctics of Mammals are as follows:

• Mammals are animals with warm blood that give birth to their offspring.
• In practically every kind of habitat, they are the most prevalent animal form.
• Their mammary glands aid in the production of milk, which they use to nourish their young.
• The brain region referred to as the Neocortex is present.
• Sebaceous glands, which produce animal oil, and sudoriferous glands, which produce sweat, are found in their skin.
• Animals' ability to adapt to their surroundings is aided by the fur and hair on their bodies.
• They are heterodont, i.e., possess different types of teeth.
• Mammals also possess cervical vertebrae.
• The skull is dicondylic.
• The trunk is divided into thorax and abdomen.
• The lungs are used by mammals to breathe.
• Good sense of hearing because mammals have three middle ear bones to help them hear.
• Mammals have a four-chambered heart. The sinus venous and renal portal system are absent.
• lower jaws with a single bone present.
• The cerebrum, cerebellum, and medulla comprise the well-developed brain.
• Exhibit one of the most advanced forms of diaphragms. They have twelve pairs of nerves in their skulls.
• The mammals can lay eggs as well. They are known as viviparous.

Also Read: Anatomy & Physiology of Human Skeletal System

Types of Mammals

Mammals appeared over 200 million years ago during the dinosaur era. While initially small, their evolution surged after the extinction of dinosaurs around 66 million years ago, resulting in the development of larger forms. Distinguished by warm-bloodedness and fur, mammals thrive in a variety of habitats worldwide, spanning from icy polar regions to lush tropical forests. Generally, mammals fall under the kingdom Animalia, phylum Chordata, and class Mammalia. The widely accepted categorization of mammals is based on three major reproductive methods:

• Monotremes Mammals
• Marsupial Mammals
• Placental Mammals

Also Read: Classification Of Animals

Classification of Mammals

Mammalia is the largest class in the animal kingdom, encompassing various types that can be categorized into smaller, larger, and marine mammals. They are further classified into two subclasses based on their reproduction.

• Eutheria
• Metatheria
• Prototheria

Eutheria

This infraclass includes mammals that give birth to well-developed offspring or deliver them directly. The embryos form within the mother's stomach, where they undergo a specific period of growth, obtaining nutrition from the mother's placenta for their development. In total, this infraclass encompasses 19 orders.

Also Read:Overview On Viviparous, Oviparous & Development of Embryo

Metatheria

Females in this infraclass are distinguished by the possession of a marsupium or brood pouch, earning them the designation of marsupials or pouched mammals. Immature offspring are born to these mammals and undergo development within their mother's pouch until reaching maturity. With over 250 species, they inhabit regions across Australia, Papua New Guinea, and certain parts of America. For example, kangaroos, koalas and possums.

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

Prototheria

Prototherians, recognized as the most primitive mammals, are exclusively found in Australia and its neighboring islands like Tasmania and New Guinea. Also known as Monotremes, this subclass is characterized by egg-laying mammals, and it encompasses a single order comprising six species. Example: Duck Billed platypus (Ornithorhyncus), Echidna (Tachyglossus).

• Order: Monotremata

Also Read: Evolution

General Classification of Mammals

General Classification of Mammals is as follows:

Example of Mammals

There are over 5,000 species of mammals on Earth. Mammals are found all over the world, from the coldest Arctic regions to the hottest deserts. They are the most diverse group of animals on Earth. Some examples of mammals include:

1. Humans
2. Dogs
3. Cats
4. Whales
5. Dolphins
6. Bats
7. Elephants
8. Horse,
9. Cows
10. Mice
11. Rats

The largest orders of mammals by number of species are Rodents, Bats, Eulipotyphla, Primates, Even-toed ungulates, Carnivora.

Conclusion - Mammals

Mammals are warm-blooded vertebrate animals with hair or fur, a large brain, and mammary glands that produce milk to feed their young. They are the most dominant form of animals found in almost all types of habitats. Mammals are divided into three groups: monotremes, marsupials, and placentals. Monotremes are mammals that lay eggs, such as the platypus and echidna. 

Marsupials are mammals that carry their young in a pouch, such as kangaroos, koalas, and opossums. Placental mammals are characterized by the presence of a placenta, such as humans, lions, and whales. Mammals are among the most intelligent of all living creatures and they include a wide variety of animals, from cats to humans to whales.

Also Read:

• Endemic Species: Meaning, Characteristics, Types and Examples
• Difference Between Humans and Animals
• Herbivore Animals
• Cold Blooded vs Warm Blooded Animals
• The Living World - Introduction, Classification, Characteristics, FAQs 
• Class Mammalia