Answer:
Deep, deep, do they go. Spreading out as they go. Never needing any air. They are sometimes as fine as hair.
I begin and have no end. Eventually I will be the end of all that has begun.
I have a mouth on my head and eat everything.
I'm really blue but when you see me I'm red. You don't see me too often. I'm there for you if you're hurt.
Although I may have eyes I cannot see. I have a round brown face with lots of acne.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.