Ever wonder why cats always -- OK, usually -- land on their feet? Or how they twist and stretch their bodies onto impossible perches? It's mostly because of their super-flexible spines. Cats have 30 vertebrae, minus their tails, which vary and increase the count to 48 to 53 vertebrae.
All cats are not created equal -- at least not in terms of how many vertebrae they have. Minus tails, it's straightforward. All cats have seven neck bones, 13 back bones with ribs, seven without ribs and three fused together at the pelvis. That's 30. Cat tails have vertebrae, though, and the number varies by breed and, sometimes, individual. Cats with longer tails have as many as 23 vertebrae; those with shorter tails have as few as 18, creating a range of 48-53 vertebrae. These bones make up a fifth of a cats' 250-ish bones.
The number of vertebrae cats have doesn't make them especially special among mammals. The elasticity of the discs between them, though, gives them what biologists say is likely unique flexibility. Cats can rotate their backs up to 180 degrees, which is how they correct their midair orientation to land on their feet. It also allows them to flex their backs into a U shape, stick their tails straight up and model for Halloween decorations. Their flexible backbones also make them faster. Ever seen your cat get the zips? If you froze him midmotion, you'd see he's longer than usual. Cats stretch and lengthen their backs, opening up their stride.
Back and Tail Health
Cats' spinal columns end in their lower backbones, before their sacrum. This technical detail is important; it means the bunch of nerves that branch out from the end of their spinal column are intimately connected. That's why the nerves in a cat's tail, housed inside 18 to 23 vertebrae, can affect their hind legs, bladder, large intestine and anus. Tail injuries, particularly toward the base, can cause otherwise seemingly unrelated health problems. Cat tail vertebrae are smaller and more cylindrical than the bones in a cat's spine. This allows cats to swish their tails in fluid, almost serpentine movements. That's right, "allow" -- cats can control their tail movements.
The Telltale No-Tail
Cats can live full, productive lives without tails -- well, productive in the kitty cat world, at least. All such cats have at least 30 vertebrae afforded by their neck, back and pelvis. Some have more, depending on why they don't have tails. Manx cats, for instance, have no tails. It's a dominant trait, genetically speaking, that also carries associated health risks. Cats with curly or kinky tails, like Japanese bobtails, have an unrelated, recessive trait. They often have additional tail vertebrae, although development can vary. Incidentally, and somewhat surprisingly, these cats have fewer negative health dispositions than cats with the Manx syndrome.
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- Cat Health Detective: Cat Spine ... Spinal Integrity of the Cat's Back
- Universities Federation for Animal Welfare: Genetic Welfare Problems of Companion Animals
- UW-L Zoo Lab: Cat Skeleton
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- Washington State University 4-H University: Cat Anatomy and Physiology
- University of Washington Biology Department: Comp. Vertebrate Anatomy
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- Michael Blann/Lifesize/Getty Images