In the X-Men comics, the superhero Wolverine is armed with three sharp claws on each arm. They extend through the skin of his hand, and the resulting wounds are closed by up his superhuman ability to ...

In Australia’s open grasslands and scrub, male kangaroos often take part in dramatic fights known as “boxing.” These battles look almost playful from a distance, but up close, they reveal one of the ...

Some African frogs carry concealed weapons: when threatened, these species puncture their own skin with sharp bones in their toes, using the bones as claws capable of wounding predators. At least 11 ...