oO0Oo<<<^>>>oO0Oo Biology oO0Oo<<<^>>>oO0Oo

This is the big one. The study of life, and this planet is literally crawling 
with life, and as such, there is a discipline for every form of life of which 
can be found. And then some. All of it makes up most of what we consider 
"Nature". IOW, it's a great place to start.