Domestic pigs come in different colours, shapes and sizes. They are usually pink, but little pigs kept as pets ("pot-bellied pigs") are sometimes other colours. Pigs roll in mud to protect themselves from sunlight. Many people think that pigs are dirty and smell. In fact, they roll around in the mud to keep bugs and ticks away from their skin. This also helps to keep their skin moist and lower their body temperature on hot days. They are omnivores, which means that they eat both plants and animals. 