Porcupine quills present an impenetrable thicket to most predators. But these backward-pointing defences are only effective if the rodent can keep its assailant to its rear.
In North America, pumas and fishers (marten-like mammals) are skilled porcupine predators, outmanoeuvring their quarry to launch their attacks from the front, or flipping the animal over to expose its soft underbelly.
Strangely, many snakes cannot resist a porcupine, even though they can be mortally wounded by the quills at the point of swallowing.
There is evidence, too, that porcupine-related injuries can turn lions, particularly young males, into man-eaters, if either the wound or resulting infection prevents them from hunting their usual prey.
Main image: Brazilian porcupine. © Ted Adams / Getty Images