There is another factor that affects sensation and perception: this plays a significant role in determining what is sensed versus what is perceived.

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.

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle