The study of chemical reactions of living this is called biochemistry.
The barnacles are only able to attach them selfs to surfaces in the water. Since the surface is limited, barnacles are attaching themselves to the other barnacles, crowding the rock. The muscles were not able to grow or attach themselves off the surface of the rock. Same thing with the mussels that are growing on the rock. So not only barnacles are crowding the rock, but Mussels as well are crowding the rock.
One reason is if someone is injured and needed to use pain pills, sometimes they get addicted to it
The answer is missense. Hope this helps!
