How do cats make their fur stand on end?
When my long-haired ragdoll cat startles my barely domesticated short-haired kitten, the kitten's tail puffs out and the fur on her back stands up all the way down her spine. The long-haired cat, no matter how scared he gets, never noticeably extends his fur. I believe cats do this when frightened or excited, and I have been told it is to look larger. What mechanism allows them to do this? Why can't they do it with all of their fur, and why can't some cats seem to do it at all? Is this in any way related to when the hair stands up on the back of a human's neck when s/he gets scared? Thanks, Stephen Tucker
Doctoral Student, Mathematics Education and Leadership
Utah State University
Ginny - So yeah, I think this is probably a very similar mechanism. So, when we get cold or when we get scared, the muscles that hold the base of our hair in place contract and that makes the hairs on our arms or on the back of our neck stand up. But you might notice that it doesn't happen to the hair on our heads and that's probably for the same reason that it doesn't happen to your longhaired cat. That's just that the hair is too long. So, these are only very tiny differences that are happening in the skin. But because the hair on your arms is quite light, it's quite short, it can make it stand up. It would just be too much weight and too difficult to actually make a very longhaired cat's hair stand up. If you think about the evolution of this, yes, way, way back when cats were alley cats, it was probably great to be able to puff up your tail and make yourself look bigger and scare off competitors. But actually, there's no negativity for your longhaired cat to not be able to do that because I'm assuming it's pretty pampered and doesn't have to fight off other cats very often. So, there's been no selective pressure to keep that ability. So, it doesn't really matter that they can't do it anymore.