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