Answer:
My teeth are sharp, my back is straight, to cut things up it is my fate.
What can be heard and caught but never seen?
I am whole but incomplete. I have no eyes, yet I see. You can see, and see right through me. My largest part is one fourth of what I once was.
You use it between your head and your toes, the more it works the thinner it grows.
I love to dance and twist and prance. I shake my tail, as away I sail. Wingless I fly into the sky.
Brings the sky a lot closer.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?