The answer is true, they are only single celled!
        
             
        
        
        
I don't understand, what is the question you're supposed to answer?
 
        
                    
             
        
        
        
1. The central nervous system including brain and spinal cord.
2. The peripheral nervous system including nerves coming out from the brain and spinal cord, i.e., cranial nerves and spinal nerves.
3. The autonomic nervous system including sympathetic nervous system and parasympathetic nervous system.
 
 
        
                    
             
        
        
        
Answer:
The organelles in an animal cell are as follows:
cell membrane, nucleus, nucleolus, nuclear membrane, cytosol, smooth endoplasmic reticulum, rough endoplasmic reticulum, Golgi apparatus, ribosomes, mitochondria, centrosome, cytoskeleton, vacuoles, vesicles, and lysosomes. 
Explanation:
An animal cell is a typical example of an eukaryotic cell i.e a cell that contains a membrane-bound nucleus. In the cell are certain structures that performs specific functions in the cell called ORGANELLES. The organelles, according to this question, are found suspended or cushioned in the cytoplasm of the animal cell. 
A list of the organelles in the cytoplasm (part of the cell that excludes the nucleus) of an animal cell are as follows:
- cell membrane
- nucleus 
- nucleolus 
- nuclear membrane
- cytosol
- smooth endoplasmic reticulum
- rough endoplasmic reticulum
- Golgi apparatus
- ribosomes
- mitochondria 
- centrosome 
- cytoskeleton
- vacuoles
- vesicles
- lysosomes
 
        
             
        
        
        
Well If the Salmon die from lack of food from polution or something, and other animals benafit from the nutrience they carry. the rest of the ecosystem might parish, i hope that helped im not sure what was wanted