There's nothing quite as enjoyable as having a day out in the fresh air and sunshine, but if you're not careful, it can come at a cost—sunburn. You might be surprised to learn that it isn't only humans who get sunburned, though; this is a problem that exists throughout the animal kingdom. Most animals have fur, feathers, or scales to protect themselves from the harmful rays of the sun; however, hairless animals such as elephants, hippos, and pigs are particularly at risk of sunburn. It's no surprise, then, that many of these animals have developed their own adaptations to protect their skin. Pigs, for example, like to roll in the mud. This behavior isn't a dirty habit; rather, the coating of mud keeps them cool in hot weather and prevents damage from strong sunlight. Similarly, elephants throw sand on their backs and heads for use as a kind of natural sunblock. Hippos, on the other hand, have developed a physical adaptation—they produce a red-colored substance around their eyes and ears which acts as a natural sunscreen by absorbing ultraviolet light.