Mammals are highly developed animals.

• Like birds, they are warm-blooded.
• They have efficient respiratory and circulatory systems.
• They have well-developed senses.
• Their well-developed brains enable them to adapt to different circumstances.
• Many mammals are quick learners.

Mammals are characterized by the presence of mammary glands in females. A new individual develops in the female's uterus. After birth, females use their mammary glands to breastfeed their young. 

Mammals are found everywhere on the planet. The best-known orders of mammals are Chiroptera (bats), Cetartiodactyla (whales and even-toed ungulates = the animals with hooves), Carnivora (cats, dogs, seals, and others), Rodentia (mice, rats and other gnawing mammals) and primates (apes, monkeys, and others).

List of mammal genera