Because they have power to move.
Producers are green plants or photosynthetic organisms that are the basis for the other living parts of any ecosystem. Producers need to have access to light to produce food. Few producers will be found deep below a lakes surface simply because the deeper you travel under water the less light penetrates those deeper layers.
Answer is somatic; autonomic
The peripheral nervous system is made up of two systems; the somatic nervous system and the autonomic nervous system.The somatic nervous system is under voluntary control and transmits signal from brain to muscles, whereas he autonomic nervous system controls involuntary actions to regulate physiological functions such as working of cardiac muscles, bladder.
The rock found in the riverbed that is smooth is from the result of weathering of water in the river and erosion. The rock deep underground was most likely a product of erosion. The dirt and ground above it were eroded and displaced there to cover the rock.
Well, experimentation can be really expensive, so when funding is provided it gets rid of a lot of obstacles.
