Unicellular organisms are organisms that can survive without the help of other cells. They are complex as the cell is complex. Many people consider them simple creatures. There is nothing simple concerning the cell. A multicelluler organisms is much more complex since there is an interdependence of cells making up their body. Their cells seem to be more specialized in a way as to complement the entire organism. Their cells have lost their independence and cannot live alone out side the organism. The entire organism depends upon the health of all its cells to survive. Nerve cells cannot do what muscle cells can do functionally. In a single celled organism they have the mechanisms to move, reproduce, sense the environment all in one