Which macromolecule forms a double layer as the primary structure of cell membranes

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.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: