What are the two little black dots at one end of the planarian called? what do they do for this organism?

Two little dots at the end of Planaria are called eye-spots.
Eye-spots (also known as ocelli) have a role in the vision of Planaria. The eye-spots have a possibility to detect the intensity of light and are used to move away from light sources.

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.