Mammals have characteristics in their cells and bodies that help classify them as mammals. All mammals are vertebrates, are endothermic, have hair on their bodies and produce milk in order to feed their young.
A fish is not a mammal. Mammals are animals that are warm-blooded, breathe air, possess hair and give birth to live young that they feed milk from mammary glands. Fish are cold-blooded, extract oxygen from water, have scales and lay eggs.
Humans are classified as mammals. Like other mammals, humans have body hair, suckle their young with milk produced from special glands on their chests, possess differentiated teeth and a four-chambered heart, and become pregnant rather than lay eggs.
Birds are not mammals. They don't have fur, and they don't nurse their young with milk as mammals do; however, birds share some traits with mammals. They are warm blooded and can eat a wide variety of food, from fruits and seeds to reptiles, fish, small mammals and other birds.
Dogs are mammals. They are warm-blooded, which means they generate the heat of their own bodies. They have fur, and mother dogs feed their young with milk produced by their bodies.
The food eaten by mammals varies based on the type of mammal, the season and the environment. Mammals can be classified as carnivores, herbivores and omnivores. Carnivores primarily eat meat, herbivores primarily eat plants and omnivores eat both.
Mammals live in almost every habitat on Earth. This includes habitats in polar regions, oceans and tropical forests. The survival of mammals in almost all environments is largely a result of their various adaptations.
Mammals have warm blood and hair on some or all of their bodies, and because a turtle lacks both of these things, it is not a mammal. A turtle is a reptile.
Mammals, including humans, belong to the Mammalian class, which is the highest order of vertebrates. Mammals have a backbone, grow hair, produce milk for the nourishment of their young via mammary glands and are warm-blooded, or endothermic.
All whales are mammals. Whales, along with dolphins and porpoises, are cetaceans, meaning that they are part of the order Cetacea, one of the taxonomic branches of marine mammals.