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Mammals vs. Reptiles: What's the Difference?

Edited by Janet White || By Harlon Moss || Updated on October 28, 2023
Mammals are warm-blooded vertebrates with hair or fur, while reptiles are cold-blooded vertebrates with scales.

Key Differences

Mammals are a class of animals characterized by their warm-blooded nature, which means they can regulate their body temperature internally. Reptiles, on the other hand, are cold-blooded, relying on external sources like the sun to regulate their body temperature.
Mammals typically have hair or fur covering their bodies, which can serve various purposes such as insulation or camouflage. In contrast, reptiles possess scales, which can offer protection or aid in moisture retention.
The way these animals reproduce also varies. Mammals usually give birth to live young, nourishing them with milk produced by mammary glands. Reptiles generally lay eggs, though some species do give birth to live young.
Another distinct difference is in heart structure: most mammals have a four-chambered heart, ensuring efficient separation of oxygenated and deoxygenated blood, while most reptiles have a three-chambered heart.

Comparison Chart

Body Temperature


Body Covering

Hair or fur


Mostly live birth & produce milk
Mostly lay eggs

Heart Chambers

Four chambers
Typically three chambers

Typical Habitat

Diverse (land, air, sea)
Primarily land & water

Mammals and Reptiles Definitions


Mammals are warm-blooded vertebrates.
Humans, as mammals, can regulate their body temperature internally.


Reptiles have scales covering their bodies.
The shiny scales on snakes, which are reptiles, help them move smoothly.


Mammals give birth to live young.
Kangaroos, being mammals, have pouches for their live-born young.


Reptiles are cold-blooded vertebrates.
Lizards, being reptiles, bask in the sun to regulate their temperature.


Mammals have a four-chambered heart.
The efficient circulation in mammals is due to their four-chambered heart.


Reptiles are primarily terrestrial or aquatic.
Many reptiles, like alligators, can be found in freshwater habitats.


Mammals possess hair or fur on their bodies.
Unlike reptiles, mammals like lions have a fur coat.


Reptiles typically have a three-chambered heart.
Reptiles, like crocodiles, have a different heart structure than mammals.


Mammals produce milk for their offspring.
Mammals, such as cows, are often sources of milk for human consumption.


Reptiles usually lay eggs for reproduction.
Turtles, as reptiles, bury their eggs in sandy beaches.


Any of various warm-blooded vertebrate animals of the class Mammalia, including humans, characterized by a covering of hair on the skin and, in the female, milk-producing mammary glands for nourishing the young.


Any of various usually cold-blooded egg-laying vertebrates often grouped in the class Reptilia, having dry skin covered with scales or horny plates and breathing by means of lungs, and including the snakes, lizards, crocodilians, and turtles. In some classification systems, birds are considered to be reptiles because they are descended from reptilian dinosaurs.


Plural of mammal


A person regarded as contemptible or obsequious.


Plural of reptile


Do all mammals have live births?

While most mammals give birth to live young, some, like the platypus, lay eggs.

Are humans considered mammals?

Yes, humans are classified as mammals.

Do reptiles have fur or hair?

No, reptiles have scales, not fur or hair.

Can reptiles live in cold climates?

Some reptiles, like certain turtles, can tolerate cold, but most prefer warmer environments.

Why do mammals produce milk?

Mammals produce milk to nourish and provide antibodies to their young.

Do reptiles care for their young?

Some reptiles, like crocodiles, show parental care, but many do not.

Do all mammals have a four-chambered heart?

Most mammals have a four-chambered heart, but there are exceptions.

What defines reptiles?

Reptiles are cold-blooded vertebrates with scales and typically lay eggs.

Are mammals found in water?

Yes, some mammals like dolphins and whales are aquatic.

How do mammals regulate their body temperature?

Mammals are warm-blooded and can regulate temperature internally.

Do mammals have scales?

No, mammals have hair or fur, not scales.

What makes mammals unique?

Mammals are warm-blooded, have hair or fur, and produce milk for their young.

Are reptiles found in the air?

While not true fliers, some reptiles, like the flying lizard, can glide.

Are snakes considered reptiles?

Yes, snakes are a type of reptile.

Can reptiles produce milk?

No, only mammals produce milk.

Which group is more diverse, mammals or reptiles?

Both groups are diverse, but there are more known species of reptiles than mammals.

Are bats considered mammals?

Yes, bats are mammals, and they can fly.

Are reptiles vertebrates?

Yes, reptiles are vertebrates, meaning they have a backbone.

Why do reptiles bask in the sun?

Being cold-blooded, reptiles bask to regulate their body temperature.

How many heart chambers do reptiles have?

Most reptiles have a three-chambered heart, but crocodilians have four.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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