Chameleons keep their eyes on the prize
New research suggests these fascinating reptiles can coordinate their eyesight.
A major evolutionary asset of the chameleon is its eyesight. Its eyes move independently of each other, allowing it to track an object while simultaneously scanning the rest of its surrounding environment.
But it's long been unclear whether these two different perspectives are processed together or separately. That is until recently, thanks to researchers at the University of Haifa, in Israel.
"When prey (an insect) is detected, the chameleon's eyes converge to view it binocularly and ‘lock’ in their sockets so that subsequent visual tracking is by head movements," the researchers wrote in The Journal of Experimental Biology. However, the extent of the eyes’ independence was unclear. For example, the researchers wondered, "Can a chameleon visually track two small targets simultaneously and monocularly, i.e. one with each eye?"
To answer this question, the researchers conducted an experiment that baited a chameleon with pixelated prey on a screen in front of it. In some of the tests, once the chameleon had fixed its eyes on the bug and locked its tongue in firing position, the prey would split in two. The fragmentation caused a few seconds of confusion, but by keeping one eye on a target, and aligning one eye to match the other's gaze, the chameleon would eventually choose a single piece.
This would suggest that a chameleon’s brain can coordinate its eyes to help it decide what to focus on, even though the eyes move independently.
"To our knowledge, this is the first demonstration of such a capacity," the researchers wrote.
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