ambush hunting. A 2010 study at Sydney
University found that of 127 Australian
snake species, the ones that ambushed
their prey by night had vertical pupils,
while those that actively chased down
prey in the day had round pupils. The
constriction of round pupils helps distant
prey stay in focus, but it also lets in less
light. Vertical pupils improve vision across
a wider range of light levels, and enable the
animal to detect horizontal movement more
effectively. It’s also possible that vertical
pupils are more camouflaged, since they
break up the round outline of the eye.
