Mammals are distinguished from other animal groups by several key characteristics:
1. **Hair or Fur**: Most mammals have hair or fur on their bodies, which helps regulate body temperature and provides protection.
2. **Mammary Glands**: Mammals have mammary glands that produce milk to nourish their young.
3. **Endothermy**: Mammals are warm-blooded, meaning they can regulate their internal body temperature independently of the external environment.
4. **Live Birth**: Most mammals give birth to live offspring rather than laying eggs, although there are exceptions like monotremes (e.g., platypus) that lay eggs.
5. **Specialized Teeth**: Mammals typically have differentiated teeth, including incisors, canines, premolars, and molars, adapted for various dietary habits.
6. **Diaphragm**: Mammals have a diaphragm, a muscular partition separating the chest and abdominal cavities, which aids in breathing.
7. **Four-Chambered Heart**: Mammals have a four-chambered heart, which efficiently pumps oxygenated and deoxygenated blood.
8. **Complex Brain**: Mammals have relatively large, complex brains compared to other animals, enabling advanced cognitive abilities.
9. **Parental Care**: Many mammals exhibit parental care, including nurturing and protecting their offspring.
10. **Vivipary and Placenta**: Some mammals have a placenta that allows for more advanced nourishment and longer gestation periods during pregnancy.
These distinguishing characteristics collectively set mammals apart from other animal groups, making them a diverse and successful class of vertebrates with a wide range of species adapted to various ecological niches.