Why does the earth have such a diversity of plant and animal life?

they both go up but then go back down. they both end lower than they started. lastly, they both are competitive/the second on.

explanation:

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.