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:
“Whatever else American thinkers do, they psychologize, often brilliantly. The trouble is that psychology only takes us so far. The new interest in families has its merits, but it will have done us all a disservice if it turns us away from public issues to private matters. A vision of things that has no room for the inner life is bankrupt, but a psychology without social analysis or politics is both powerless and very lonely.”
—Joseph Featherstone (20th century)
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—Joseph De Maistre (1753–1821)
“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)