What kind of animal can do this?
Although your plastic bag tears are most likely due to light damage as @Chris mentioned above, there is a type of ant that chews its way through plastic, rubber and other manufactured polymers: Monomorium pharaonis, the Pharaoh ant.



It is capable of destroying many manufactured materials and is a great example of budding, a method by which new ant colonies form. They are very invasive and difficult to control.