Answer:
I cannot be burned in fire or drowned in water
The more holes you cover the lower I go.
I transfer oxygen from the atmosphere to your blood
I wiggle and cannot see; sometimes underground and sometimes on a tree. I really don't want to be on a hook and I become a person when combined with “book”.
I am so delicate that even mentioning me breaks me. What am I?
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk