Philippe Clement / Lynx (Lynx lynx) sharpening claws on tree trunk before walking away, Germany, May. Captive

Edwin Giesbers / Lynx (Lynx lynx) stretching and sharpening claws, Germany, July. Captive.

Philippe Clement / Lynx (Lynx lynx) stretching and sharpening claws on fallen tree trunk, Isselburg, Germany, October. Captive.

Christophe Courteau / Lion (Panthera leo) male sharpening his claws on a tree at night, Sabi Sand Game Reserve, South Africa.

Yukihiro Fukuda / Feral domestic rabbit (Oryctolagus cuniculus) sharpening claws, Okunojima Island, also known as Rabbit Island, Hiroshima, Japan.

Alex Mustard / Diver re-sharpens the points of his lionfish (Pterois volitans) hand spear. Lionfish are native to the Indo-Pacific, but introduced to the Caribbean Sea from aquariums, they are now widespread, abunda...

Ann & Steve Toon / Male Cheetah (Acinonyx jubatus) sharpening claws against a tree trunk, Kgalagadi Transfrontier Park, Northern Cape, South Africa.