My
Night Vision
By Christopher Widuch
“
! What big eyes you have , Grandma !” These were the famous words of Little Red Riding Hood when she stumbled upon a wolf in her grandmother ’ s home . She likely didn ’ t give a moment ’ s thought to the importance of big eyes to the wolf ’ s survival . Little Red quickly became more concerned with escape than understanding how some animals thrive at night while others struggle .
As human beings , we typically retreat into our homes as the sun sets and darkness prevails . It is a chance for us to wind down , to relax and reflect on the day ’ s events and the next day ’ s anticipations . Animals view the advent of night from a different perspective . Many work the night shift , nocturnal in nature and welcoming of the dark . They prowl , hunt , mate , even play in the dark . They are designed to thrive at night , unlike people who are considered diurnal , a term derived from the Latin diurnus meaning “ of the day ” or daily .
What is it that sets nocturnal animals apart from those who hunker down at night ? Clearly , the eyes hold the key . There are a number of features that allow certain animals to see at night better than others . Three of the most important traits are large eyes , an abundance of rods versus cones , and a membrane called the tapetum lucidum .
For night vision , the larger the eyes the better . Simply put , big eyes capture more light . Owls have eyes that take up about half the volume of their skulls . They are also blessed with a large lens that is located very close to the back of the eye , next to the retina . This large lens allows the retina to capture more light than other animals . There is one drawback , however , to the large amount of space their eyeballs consume . Their eyes are so big the owl can ’ t actually move them ; instead , they rotate their heads 270 degrees when they want to see what is to their sides .
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