RNA viruses can copy themselves which is harder for scientists to give an accurate conclusion to solve them.
        
             
        
        
        
The storage areas are called : Reservoirs Reservoirs can both be made by nature or crafted by men. In order to make our lives became easier , we could create our own reservioir by digging up an open land to form a space that could contain water when its raining, as a back up resources when the lake or rivers are drying up
        
             
        
        
        
The first invertebrates to show both segmentation and a complete digestive system belong to the phylum Annelida that includes earthworms, leech, sandworms, etc. 
These segmented worms have complete digestive system which is also known as tube-within a tube. These can be found in freshwater, marine water or can even be terrestrial.