They have hair on their bodies. They nurse their young. They have live birth rather than laying eggs, There are several major groups of mammals. It has developed muscles and generally have four limbs attached. Digestion A mammal has a developed digestive tract with mouth, teeth, stomach, intestines.
Herbivores eat plants, carnivores eat meat and omnivores eat both.
A mammal has a highly developed brain, nerves and sensory organs such as eyes, nose, mouth, ears and touch. Circulation A mammal has a four chambered heart, blood vessels and blood within their system. A mammal has lungs and breathes in oxygen and gives off carbon dioxide. Reproduction A mammal reproduces sexually with the female being fertilized by the male internally. Mammals have live birth and care for their young for quite a time after birth.