General Features:
* Hair or fur: Mammals are the only animals that have hair or fur, even if it's very fine or sparse.
* Warm-blooded: Mammals are endothermic, meaning they can regulate their own body temperature. You might be able to deduce this by observing their activity level in different environments.
* Give birth to live young: While some reptiles like snakes also give live birth, mammals typically do.
* Nurse their young: Mammals have mammary glands that produce milk to feed their offspring.
Specific Features:
* Presence of a diaphragm: Mammals have a muscular diaphragm that helps with breathing. This is a unique feature among vertebrates.
* Four-chambered heart: Most mammals have a four-chambered heart, which helps with efficient blood circulation.
* Presence of teeth: Mammals have specialized teeth that help them chew and digest food. Different types of mammals have different types of teeth.
Important Notes:
* Some mammals, like whales and dolphins, have adapted to an aquatic lifestyle and may not have obvious hair or fur.
* Some mammals, like platypuses and echidnas, lay eggs, which seems like a reptilian characteristic, but they still nurse their young.
It's crucial to remember that these features are not always foolproof. Many animals may share some characteristics with mammals. For example, birds have feathers but are not mammals, and some reptiles have scales that may resemble fur.
If you're unsure about an animal's classification, it's best to consult a reliable source or an expert in the field.