Vertebrae include fish, amphibians, reptiles, birds, and mammals. Analyze the common characteristics of reptiles and explain how they differ from mammals.

Reptiles are a class of vertebrates that includes animals such as snakes, lizards, turtles, and crocodiles. They share several common characteristics that distinguish them from mammals:

1. Skin: Reptiles have dry, scaly skin that helps prevent water loss and protects them from environmental hazards. In contrast, mammals have fur or hair that helps regulate body temperature and provides insulation.

2. Reproduction: Most reptiles lay eggs, although some give birth to live young. Mammals, on the other hand, give birth to live young and nurse their offspring with milk produced by mammary glands.

3. Metabolism: Reptiles are ectothermic, meaning they rely on external sources of heat to regulate their body temperature. This often results in reptiles being more active during warmer periods of the day. Mammals, on the other hand, are endothermic and can regulate their body temperature internally, allowing them to be active at any time.

4. Teeth: Reptiles typically have multiple sets of teeth that are replaced throughout their lives. Mammals, on the other hand, generally have two sets of teeth – baby teeth and permanent teeth.

5. Respiratory system: Reptiles have a more primitive respiratory system compared to mammals, with most relying on lungs for breathing. Some species of reptiles also have the ability to breathe through their skin. Mammals have a more complex respiratory system, with a diaphragm that helps control breathing.

Overall, reptiles and mammals have evolved different adaptations to suit their respective environments and lifestyles. Reptiles are generally more suited to drier, warmer climates, while mammals have adapted to a wider range of habitats and lifestyles.