Answer:
My teeth are sharp, my back is straight, to cut things up it is my fate.
Left to right Iām quite bright. Right to left I might bite.
Take one out and scratch my head, I am now black but once was red.
Inside a great blue castle lives a shy young maid. She blushes in the morning and comes not out at night.
Three little letters, a paradox to some. The worse that it is, the better it becomes.
My days are numbered.
Difficult
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?