Mammals Are Named After Milk Glands
A mammal is a warm-blooded animal that feeds its young on milk. Linnaeus chose the defining feature deliberately.
A mammal is a warm-blooded vertebrate whose females produce milk. Linnaeus coined the class name *Mammalia* in 1758 from Latin *mamma*, a breast — choosing that feature over hair or warm blood. Some historians argue the choice was partly political, made while he was campaigning against wet-nursing and for maternal breastfeeding.
- A milk-producing vertebrate. *A marine mammal.*
- Mammalian — of mammals. *Mammalian biology.*
- Mammary gland — the milk-producing organ. *Mammary tissue.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | mammal | A small mammal. |
| Plural | mammals | Marine mammals. |
| Adjective | mammalian | Mammalian cells. |
| Class | Mammalia | The class Mammalia. |
| Related | mammary | Mammary glands. |
How it is used in a sentence
- Whales are mammals, not fish.They breathe air and produce milk.
- The platypus lays eggs.And is still a mammal.
- Linnaeus named the class in 1758.From the Latin for breast.
Mammal groups
- Monotremes — egg-laying, including the platypus and echidnas
- Marsupials — young develop in a pouch
- Placentals — young develop in the womb, the largest group
- Shared features — hair, milk, three middle ear bones
- Around 6,500 species — with new ones still being described
From Latin *mamma*, a breast, coined by Linnaeus as *Mammalia* in the tenth edition of Systema Naturae, 1758.
Do all mammals give birth to live young?
No. Monotremes such as the platypus lay eggs, but they still produce milk, which is the defining feature.
Why milk rather than hair?
Both are defining features. Linnaeus chose milk, and some historians link the choice to his campaigning for maternal breastfeeding.