Hey Oldcat, I have a question. Is there a reason so many cats have a pretty good symmetry to their patterning?
Yes, there is a reason – almost all animals above the level of any complexity have an overall bilateral symmetry – basically the left and right sides are more or less identical as if reflected in a mirror down the centerline of the body.
When an embryo is tiny, it has little to no structure, no nerves, no blood vessels. Yet it needs to send ‘messages’ to parts of itself to ‘order’ the development. This is done by chemical cues. As these cues spread out from the centerline where the nervous system is forming, they tend to do so with general symmetry, because the spreading has no reason to prefer left or right. White Spotting is thought to occur because the cue to color the hair in skin cells does not reach the parts of the cat furthest from the head and spine.
So maybe we should be asking why a pattern is ever not symmetric?
Well one kind of pattern that is not symmetric is the X inactivation that produces tortoiseshell cats. Female cats, like all female mammals, have two X chromosomes, while Males have only one – the second is the sex determining Y, which has no other genetic use. (Insert joke about useless parts on men here). Since the cell is built for one X, the embryo must pick one or the other to use. This is essentially a random choice, so there is no symmetry needed. This also means that females are genetically a mix of two different genetic patterns – some cells use one X, others the other. (Insert joke about females and being of two minds here).
minlit also asks:
Is it a myth, or are cats’ whiskers related to their girth? If so, what happens when a fat cat gets thinner? I’ve always wondered about that! D
I’ve heard the theory, but I don’t see how the whiskers could know how fat a cat was. It is even hard to see how they could reliably be used to check the size of the head. Also, if you look at it, cats hate to have their whiskers touch things, instead they fold them back if going into a tight space. They have good vision.
Plus, I have seen cats get their head stuck in things, so it doesn’t work all the time anyway.