How does gravity cause plates to move?
Explain

The main driving force of plate tectonics is gravity. If a plate with oceanic lithosphere meets another plate, the dense oceanic lithosphere dives beneath the other plate and sinks into the mantle. The sinking oceanic lithosphere drags the rest of the tectonic plate and this is the main cause of plate motion. This process is called subduction.

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.