There are over one billion sheep in the world.A group of sheep is known as a herd, or a mob.Young sheep are called lambs.Adult sheep are called rams.China has the largest number of sheep in the world.Adult female sheep are known as ewes.Sheep are herbivores that eat vegetation such as grass.Sheep have a  field vision of around of 300 degrees, allowing them to see behind themselves without having to turn there head around.The digestive system  of sheep features four chambers that help break  down what they eat.Sheep stay close to others in a herd which makes it easier to move around together to new pastures.