Expert: Florence M Rollwagen - 7/18/2008

Question
i watch squirrels during the day.
they constantly claw there way up and down trees and telephone poles.
their claws may be tough, but they are keratin, and must lose their sharpness over time
how do they or any animal sharpen their claws.
it cant be as simple as rubbing them against a hard surface, this would further dull them.
like sharpening a pencil, they would have to apply some kind of motion equally on all sides of the claw against an abrasive surface.
ive never seen a cat or squirrel or any clawed creature do something like this.
also continued growth from the base of the nail bed would not explain how the sharpness is maintained as the new growth is wide and from the base
can you explain how animals maintain the sharpness of their claws?
i am unable to find an answer on the internet, or through logical thinking.
if you cannot answer this, can you suggest an avenue of research?
thank you

Answer
Squirrel Claw Sharpening

Hi Feiv: Thanks for your question.

It took me some time to find out about this question, it’s not one of my “regulars”!

There was nothing on squirrel claws, as you found out, but I searched “rodent claws”  since squirrels are rodents.

Here’s what I found and the correct site:

The rat nail grows outward from the bed, and consists of a hard external layer (unguis) and a softer underlayer (subunguis).  I suspect that when the squirrel (rat) uses its claws, the softer part is worn away at a faster rate, leaving the denser material above which is used for climbing.  The claw curves around into a point because that’s the way the toe grows.

http://www.ratbehavior.org/claws.htm

That’s all I could find.  Hope it helps.  By the way, cats also sharpen their claws on carpets, blankets and trees, so they’re similar, although not rodents.

I also saw where you asked “Ask a Biologist”  Good luck!

FM Rollwagen, PhD