1. Development:
* Gestation: Mammals develop inside their mother's body, nourished by a placenta (except for monotremes, who lay eggs).
* Birth: All mammals are born live, unlike reptiles, birds, fish, etc.
* Lactation: Mothers nurse their young with milk, providing them with essential nutrients and antibodies.
2. Growth and Development:
* Infancy: Mammals are typically born helpless and require parental care for a period of time. This varies significantly depending on the species.
* Juvenile stage: As mammals grow, they develop physical abilities and learn survival skills from their parents or peers.
* Adolescence: This stage marks the transition to adulthood, often accompanied by hormonal changes and social interactions.
3. Reproduction:
* Maturity: Mammals reach sexual maturity and become capable of reproducing.
* Reproduction: They mate and produce offspring, continuing the cycle of life.
4. Aging and Death:
* Senescence: As mammals age, their bodies decline in function, becoming more susceptible to diseases and eventually death.
Beyond these general stages, mammals also share several common features:
* Hair or fur: Mammals are the only group of animals that have hair or fur. This helps them regulate their body temperature and provides insulation.
* Warm-blooded: Mammals are warm-blooded, meaning they can regulate their own body temperature.
* Mammary glands: These glands produce milk to nourish their young.
* Three middle ear bones: Mammals have three middle ear bones (malleus, incus, and stapes), which are crucial for hearing.
* Four-chambered heart: Mammals have a four-chambered heart, which allows for efficient oxygen transport throughout the body.
It's important to note that the specific details of these stages and features vary greatly across the thousands of mammal species.