What is a mammal?

• Mammals are animals that have certain characteristics in common.  
• Most mammals give birth to live babies, and all mammals look after their young.
• All mammals are warm-blooded and breathe air, and all have hair at some stage in their development.
• Only a mammal feeds its babies with milk so if a creature is fed with milk when it is young, it is a mammal.  
•  There are over 4000 different kinds of mammal in the world.  
• Most mammals have four legs, but not all of them.  
• Most mammals live on land, but some don’t.
• All mammals can communicate with each other.  
• All mammals are vertebrates: they have a backbone and skeleton to give shape to their bodies.  
• A mammal is a warm-blooded animal that breathes air, has a skeleton and feeds its babies with milk.