Answer:
Ripped from my mother's womb. Beaten and burned, I become a blood thirsty killer.
Only two backbones and thousands of ribs.
A skin have I, more eyes than one. I can be very nice when I am done.
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
What is it that given one, you’ll have either two or none?
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?