why protozoas are acellular instead of being unicellular. Difference between unicellular and acellular.

Hi Mahak,
Most protozoans are called as unicellular organisms.
Very few books says and menion them as Acellular organisms
(No shape/only one cell “A cell”).
The acellular means no proper sturcture in cell.
The protozoans change their shape often such as Amoeba,Entamoeba,Giardia and many more.
Similarly several other organisms like paramoecium,Vorticella and many flagellated protozans change their shape during movement (locomotion), so their shape changes continuously.
Thus Protozoans are acellular

Protozoans called acellular bcoz they have not definate covering of protoplasm while in unicellular protoplasm is covered by definate covering that makes a proper cell.