Kittens can be polydactyl. Polydactyl means an extra toe. It is harmless and will not be a problem. It is a genetic feature of some cats.
Polydactyly is the term for the presence of extra fingers. Syndactyly is the term for fused fingers.
polydactylly
polydactyl means many fingers. It refers to people or creatures that have more fingers or toes then what they are suppose to have.
It is not uncommon for some cats to have extra toes on the front or back feet. It is said that a cat with these extra toes are good luck.
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Because they move. Cats are highly attuned to small things moving. Even if you have trained them not to play with your fingers, they will watch them because they find the motion fascinating. This is linked to their hunting instinct.
By instinct cats are attracted to movement of small things. It is a predatory instinct for hunting. But often a cat will become playful if you wiggle your fingers at them, and will attack/play with your fingers by pouncing or swatting at them.
Because a spanner provides extra leverage - and is much tougher than our fingers !
A suspected criminal with extra fingers?
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An Extra Flap Of Fur On Cats