Which Animal Has Seven Bones In Its Neck?

By Antonia Čirjak on June 16 2020 in Did You Know

Unlike most other mammals, sloths can have up to 10 bones in their necks.
Unlike most other mammals, sloths can have up to 10 bones in their necks.
  • All mammals have seven bones in their necks, exept for two species - sloths and manatees.
  • Sloths and manattes can both have up to 10 bones in their necks.
  • These two species are able to stop cells from multiplying and creating tumors, just by having a much slower metabolism.

The answer to this question may surprise you, but all mammals actually have seven bones in their necks. Yes, even giraffes, with their extremely long necks, have the same number of bones in them as us humans do. It might seem weird, but it is so. It is an amusing thought, the fact that humans, giraffes, and mice all have similarly constructed necks, but who said science couldn’t be amusing?

Naturally, the size of the bones is not the same, but their number is! Other animal species can have a different number of bones in their necks, but all mammals have seven. Well, there are two exceptions, and we will talk about them in more detail in this article. Those two are the sloths and manatees.

The Necks Of Mammals

Unlike most other mammals, sloths can have up to 10 bones in their necks. This happens because of the extra neck vertebrae that come out of their rib cages. The skeletons of various animal species have been the subject of much research throughout history.

sloths can have up to 10 bones in their necks
Sloths can have up to 10 bones in their necks.

While many species have varying numbers of bones in their necks, mammals usually have only seven. Almost all mammals start forming their bones in the first vertebrae of their rib cages, and the other bones from before those of the neck. However, with sloths, their lowest neck vertebrae start forming even before their rib cage does.

An interesting thing was discovered while researching animal skeletons. It seems that all mammals start developing the eighth vertebra below their head, and this includes sloths. However, in sloths, the bottom vertebrae in their necks develop similarly to how the rib cage vertebrae develop in other mammals. What this means is that the lowest vertebrae in the neck of sloths are actually remarkably similar to the vertebrae in the rib cages of other mammals. However, the sloths lack those ribs.

The Changing Of the Bone Structure

The sloths manage to have this kind of bodily constitution thanks to the fact that they can slide their pelvis, ribs, and shoulder down their vertebral column. It is actually a fascinating adjustment. The fact that this single mammal specie is able to completely alter its bone structure is an incredibly interesting topic.

Sloths have six of these ribless vertebrae, and manatees are the same.
Sloths have six ribless vertebrae, and manatees are the same.

Mammals all have the same necks, and even though they have several vertebrae that have no ribs that are placed above the shoulders, these are still rib vertebrae. They might seem as they were made for neck bones, but it is not so. Sloths have six of these ribless vertebrae, and manatees are the same. The reason why these two species have such peculiar neck constitutions is still a mystery.

However, some researchers suggest that it is since they have extremely low metabolism rates. By having a slower metabolism, they are more advanced than other mammals in some cases. For example, they can block most mutations that come when body parts are added to the neck. One such mutation is cancer. They are able to stop cells from multiplying and creating tumors, just by having a much slower metabolism than most other mammals. This is definitely something that needs to be explained more thoroughly.

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