1. Mammary Glands: One of the most distinctive features of mammals is the presence of mammary glands, which produce and secrete milk for nourishing their young. These mammary glands are only found in female mammals and are responsible for lactation.
2. Fur or Hair: Mammals possess a covering of fur, hair, or both. This fur acts as an insulation, regulates body temperature, and can serve as a protective layer.
3. Endothermy or Warm-Bloodedness: Mammals are endothermic, meaning they can generate their body heat internally. This trait allows them to maintain a constant and relatively high body temperature, regardless of external temperature fluctuations.
4. Diaphragm: Mammals have a muscular structure called the diaphragm that separates the thoracic cavity from the abdominal cavity. The diaphragm plays a crucial role in respiration, aiding in the efficient expansion and contraction of the lungs.
5. Four-Chambered Heart: Unlike many other vertebrate groups, mammals possess a four-chambered heart with two atria and two ventricles. This arrangement allows for a complete separation of oxygenated and deoxygenated blood circuits, resulting in efficient oxygen transport.
6. Single Bone in Lower Jaw: Mammals have a unique jaw structure, characterized by a single bone in the lower jaw called the dentary. This single bone articulation provides strength and enhanced mobility.
7. Highly Developed Brain: Mammals possess a highly developed brain, with a complex cerebral cortex. This advanced brain structure is associated with enhanced cognitive abilities, learning, and problem-solving capabilities.
8. Specialized Teeth: Mammals have specialized teeth, adapted to their specific diets. These teeth can vary in shape and function, including incisors, canines, premolars, and molars, which serve various purposes like cutting, tearing, grinding, and chewing.
9. Uterus and Live Birth: Most mammals give birth to live young, with a few exceptions like monotremes. Female mammals have a uterus, where the embryo develops and receives nutrients until it is ready to be born.
10. Neocortex: Mammals possess a neocortex, which is a region of the cerebral cortex responsible for higher cognitive functions, such as language processing, abstract reasoning, and consciousness.
These characteristics collectively define mammals and distinguish them from other vertebrates, contributing to their evolutionary success and adaptation to diverse environments.