Mammals are a diverse group of vertebrate animals belonging to the class Mammalia.
- They are found in nearly every habitat on earth, from oceans and forests to deserts and polar regions.
- Highly evolved organisms known for their ability to regulate body temperature and care for their young.
- Warm-blooded vertebrates that have backbones, hair or fur, mammary glands, and mostly give birth to live young.
Types of Mammals
Mammals are classified into three main groups:
1. Monotremes (Egg-laying mammals)
- These type of mammals lay eggs
- Found mainly in Australia
- Examples: Platypus, Echidna
2. Marsupials
- It gives birth to underdeveloped young
- Development continues in a pouch (marsupium)
- Examples: Kangaroo, Koala
3. Placentals (Eutherians)
- It gives birth to well-developed young
- Embryo develops inside the uterus with a placenta
- Examples: Human, Elephant
Characteristics of Mammals
- Warm-blooded (maintain constant body temperature)
- Body covered with hair/fur (at least at some stage)
- Presence of mammary glands
- Heterodont dentition (different types of teeth)
- Four-chambered heart
- Well-developed brain, especially the neocortex
- Respiration through the lungs
- Presence of a diaphragm
- Three middle ear bones (malleus, incus, stapes)
- Lower jaw made of a single bone (dentary)
Classification of Mammals
The Mammalia is the largest class in the Animalia Kingdom. There are several types of mammals, including small, large, and marine mammals.
Based on reproduction, mammals are grouped into two subclasses:
Prototheria
Prototheria are the most primitive group of mammals, commonly known as monotremes. These mammals are restricted to Australia and nearby regions such as Tasmania and New Guinea. They are unique because they lay eggs instead of giving birth to live young. Prototheria includes the order Monotremata, which consists of a few living species such as the platypus and 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 marsupials or pouched mammals. The females possess a marsupium (pouch) in which the immature young continue to develop after birth. Examples include kangaroos and koalas.
- Eutheria: Eutheria are also known as placental mammals. In these animals, the embryo develops inside the uterus and receives nourishment through the placenta. In these animals, the embryo develops inside the uterus and receives nourishment through the placenta. They give birth to well-developed young.
Importance of Mammals
Mammals play a significant role in ecosystems and human life:
- Help maintain ecological balance
- Serve as sources of food, clothing, and labour
- Aid in seed dispersal and pollination
- Used in scientific research