Ero Sennin.
I HAVE NO BLOOD.
I converted my entire body to Earth.
And not just any Earth; the hardest Earth on the planet, that's been enfused with chakra. (even HARDER !)
You still haven't freed Zabuza from the cocoon of earth. I use Earth Release: Burning Spikes. I create thousands of spikes inside of the cocoon and combine them with my fire chakra to create superheated earth spikes that stab zabuza.
You can't use earth manipulation to free yourself from earth that's been enfused with another's chakra, and you can't use it to break free from my special mineral earth, which is much different from normal earth....
-_-
Don't even try.
My earth body is composed of the strongest, hardest, most chakra infused earth known to man (and monkeys). It's indestructible by everything except for some swords/jutsus, and I have the power to repair it anyway.
Plus, I've already sealed it up to not allow anyone's chakra but mine to flow through it, so if I decide to use the earth in my body for a jutsu, it can't be affected by, say, your gravity manipulation.