Rats have the ability to move their eyes in opposite directions and that’s why they can see the airspace above them.
Scientists used miniaturised high-speed cameras and high-speed behavioural tracking systems and found that the rats have the ability to move their eyes in opposite directions in both the horizontal and vertical planes.
“Humans move their eyes in a very stereotypical way for both counteracting head movements and searching around. Both our eyes move together and always follow the same object. In rats, on the other hand, the eyes generally move in opposite directions,” Jason Kerr from the Max Planck Institute for Biological Cybernetics, who is also one of the authors of the study, said in a statement.
Researchers also found that the eye movements largely depend on the position of the head.
“When the head points downward, the eyes move back, away from the tip of the nose. When the rat lifts its head, the eyes look forward: cross-eyed, so to speak. If the animal puts its head on one side, the eye on the lower side moves up and the other eye moves down,” Jason Kerr added.
Rats’ ability to move the eyes in different directions can help them in keeping a permanent view of the space above them and making them aware of the predatory birds.
“We suggest that continuously overlapping visual fields overhead would be of evolutionary benefit for predator detection by minimizing blind spots,” Researchers wrote.
Wallace, D., Greenberg, D., Sawinski, J., Rulla, S., Notaro, G., & Kerr, J. (2013). Rats maintain an overhead binocular field at the expense of constant fusion Nature DOI: 10.1038/nature12153