What are the three main categories of organelles within the cytoplasm?

Planarias are flat worms that live freely in freshwater and sometimes in teh logs, soil, plants, or other dump or humid areas. They are from the class of Turbellarians. They have a very good ability in regeneration. They are acoelomerate which means that their body is very solid without any hollows. 

They excrete unwanted objects from their body using their excretory system which is consists of series of tubes with length similar to their body length. The flame cells remove excess water through the use of the cilia and pass them to the ducts. At the end of the duct, there exist pores called the nephridiapores. 

The category is the thing that is most simmilar throughout a period