Final answer:
The Euglena is a unique unicellular organism with an eye spot, which it uses to detect light for orientation and movement.
Step-by-step explanation:
The single-celled organism that possesses an eye spot is Euglena. Euglena cells are quite complex and contain various organelles that perform vital functions. They have a contractile vacuole for expelling water, much like a kidney does in more complex organisms. The red-colored eye spot of Euglena enables it to sense light, guiding the organism's movements. It uses flagella for locomotion and is also capable of changing its shape to move, similar to the way earthworms do. Additionally, the presence of a pellicle allows Euglena to maintain a flexible structure while providing strength to the cell.
Euglena, a single-celled organism, possesses an eye spot. The eye spot is a primitive ocular organ that helps Euglena move towards light sources. The eye spot allows Euglena to detect light and orient itself accordingly.