I’ve reached the age where reading a book or a newspaper has gotten harder. I have resisted this reality for a long time. Even though I have trifocal glasses I still have a time with reading small print. My best defense is to remove my glasses and hold the item to the tip of my nose so I can make out the letters that seem to be getting smaller and smaller these days. It got me to wondering how wonderful it would be to not have an vision problems at all to deal with. I’ve always been near-sighted, but now with this change with the close-detailed work, it made me take special notice when I read about a creature with exceptional sight.
The animal is a nocturnal primate called the Tarsier. It is a small animal weighing anywhere from 3 to 6 oz. and its size is usually no bigger than 6.5”. It lives in forests and mangroves on southeast Asian islands. They have very long hind legs, and have bat-like ears that are so sensitive that they can hear even the slightest sounds. If that wasn’t enough, what makes this animal even more extraordinary is its eyes. They are 16 mm, or 5/8”, in diameter and they are as large as its brain.
Surprisingly, their eyes lack the tapetum lucidum. This is the layer of tissue lying right behind the retina that reflects visible light back through the retina. Many animals that roam the night possess this feature which increases any light available to them. Cats are a prime example of an animal who has tapetum lucidum.. If you’ve ever reflected a light at their eyes you will see them glow.
Instead of tapetum lucidum, the Tarsier have fovea. The fovea provides sharp central vision used for detailed visual activities. In humans the fovea helps us to do skills like driving and reading. The fovea is a small depression that is made up of closely packed cones in the eye and is located in the retina’s macula lutea.
With vision like this, the Tarsier can catch animals likes frogs, lizards, birds and even flying bats, to take care of their carnivorous cravings. Living in trees all day is another tricky maneuver they have to deal with, so those big beautiful eyes help get the job done.
So the next time I struggle with reading ingredients on a cereal box, I can be glad I don’t have to catch my own prey. If I did I’d be in serious trouble.