Vision
Due to the subterranean nature of this mole, there is an anatomical regression of its eyes at several organizational levels. Its eye has a diameter of only 1mm and is buried beneath fur and has a cellular lens. The organization of the retina is quite similar to that of a typical mammal. It has been determined that there are about 2000 ganglion cells and the optic nerve is roughly 50 μm with 3000 axons. Roughly 15% of these axons are mylinated. The photoreceptors are not the normal rod-like or cone-like shape that you would expect to see. Instead they all have one uniform shape with three distinct features:
- 1) The receptors are short along the radial axis
- 2)The inner and outer segments are similar in length
- 3)The outer segments appear to be significantly degenerated
Studies have shown that T.europaea does have photopic vision, contrary to popular belief that all moles are blind. Two cone opsins have been found in the eyes of T. europaea but their function is still under investigation. In a study of the mole eyes it was found that Talpa withdraws when exposed to a flashlight and can also perform light/dark discrimination tasks. The cone cells in the eye are unlikely to provide high-resolution vision but they could allow a detection of movement and some hue discrimination. It is suggested that in subterranean mammals vision is used to detect predators that have broken into the tunnels.
Read more about this topic: European Mole
Famous quotes containing the word vision:
“Our star was brighter perhaps when it had water in it.
Now there is no question even of that, but only
Of holding on to the hard earth so as not to get thrown off,
With an occasional dream, a vision ...”
—John Ashbery (b. 1927)
“To stroll is a science, it is the gastronomy of the eye. To walk is to vegetate, to stroll is to live.... To stroll is to enjoy, it is to assume a mind-set, it is to admire the sublime pictures of unhappiness, of love, of joy, of graceful or grotesque portraits; it is to plunge one’s vision to the depths of a thousand existences: young, it is to desire everything; old, it is to live the life of the young, to marry their passions.”
—Honoré De Balzac (1799–1850)
“You had such a vision of the street
As the street hardly understands;
Sitting along the bed’s edge, where
You curled the papers from your hair,
Or clasped the yellow soles of feet
In the palms of both soiled hands.”
—T.S. (Thomas Stearns)