What are the cns and pns made of?

Barnacles and mussel after filter feeders that attach themselves to rocks in the ocean. they eat by filtering small particles of food from the ocean water as it flows over them. a scientist observed a dense colony of barnacles covering the surface of the rock. the mussels were only able to attach to a few, small cervices on the same rock.< br /> < br /> evaluate the observation and explain a limiting factor that is affecting the barnacles and mussels on the ocean rock< br /> < br /> ive been reading the lesson for that past 3 hours and i still cant ..i'm dumb yeaa i know );