Answer:
John Lennon sang about being this toothy creature.
A nutcracker up in a tree
Known for their natural tuxedos and marching.
Microparasite expert at sucking the blood of mammals and birds
What screams when put in a pot of boiling water?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Animal
Difficult
Easy
Food
Funny
Kids
Logic
What am I?