What categorizes an animal as a mammal?

Answer 1

A mammal breathes air and has a backbone. (or if you want to be all sciency you can say that they are "vertebrates")

Hope this helped! I edited it from the last one which was most unhelpful! :)

Answer 2

Mammals are defined as vertebrate chordates that have hair and suckle their young, have more than 1 type of tooth and a flap on the ear that may be called a pinna. The classification is as follows: Domain Eukarya; living organisms with nuclei to contain the DNA in all cells but red blood cells Kingdom Animalia; multicellular, nonphotosynthetic organisms with nucleated cells Phylum Chordata; animals with a rod down their backs at some time of development called a notochord Subphylum Vertebrata; chordates with a true backbone Class Mammalia; as defined above there are 21 orders of mammals and 4500 species approximately

Answer 3

There are many subclassifications of mammals. However, the four characteristics that define a mammal are having hair, mammary glands, three middle ear bones, and the neocortex region of the brain.

Answer 4

Young are born alive, and not hatched from eggs, and young are nursed with milk produced by their mother.

Answer 5

depending upon the mammal sizes