Book 33, Question 9
Why do almost all mammals have seven neck bones?
A giraffe has a very long neck, and you have a short one, but both have seven neck bones.
A giraffe’s bones are just much longer. This number has stayed the same in nearly all mammals for millions of years. Only a few, such as sloths and manatees, have a different count. It’s a clue that all mammals share a family history.
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Quick answers
Why do almost all mammals have seven neck bones?
The number of neck vertebrae in mammals is virtually always seven.
Source: National Institutes of Health
More fun facts
- Despite its elongated form, the neck of a giraffe is made up of just seven large bones known as cervical vertebrae.
- Mice also have seven cervical vertebrae in their necks, though extremely small compared to those of a giraffe.
- The long neck of the giraffe has only seven vertebrae, which makes it rather stiff, such that lifting it costs considerable force.
- A large number of vertebrae make a long and flexible neck in flamingoes.
Sources: Natural History Museum, London, National Institutes of Health