Why Moles Can't See

Genetics explains moles' poor vision.

By on October 21st, 2008 08:21 GMT

It's common knowledge that moles live under ground and feed on insects, and, as a result of the adaptation to their environment, their eyes became dispersible, shows a new survey. Some mole species rarely come out and hunt on the surface, so it's obvious that they couldn't use their eyes for any reason. Talpa occidentalis, the scientific term describing the Iberian mole, is an insect hunter that keeps its eyes closed at all times, unlike others who can only see blurs.
 

This mole is special, because it doesn't use its eyes at all. The reason for this is that its eyes are not formed, not that it chooses not to open them. Scientific research conducted at the University of Aberdeen by J. Martin Collinson showed that the epithelial cells that should have formed the animal's eyes are disrupted and that the eye sockets are filled with an uneven mass of immature cells.
 

"Our results show that there are primary developmental defects in the lens of this insectivore. As a result, the adult lens is composed of a disrupted epithelium and a disorganised mass of immature and nucleated fiber cells," Collinsion explained. Further investigations showed that this was not a result of any disease or degenerative condition. Simply, sometime during the mole's early stages of life, its eye tissue stopped growing.
 

Scientists discovered that some genes related to the forming of vision receptors were showing signs of abnormal expression, which could very well be the cause for this genetic breakdown of the eye cells. However, no one has been able to figure out why this exception occurred in this species alone. Other moles, living in the U.K., for example, still retain basic vision capabilities, even though they live in the same habitat as Iberian moles.
 

The team researching moles' adaptations to living their lives in the dark published their findings, which included a detailed anatomical and genetic examination of the test subjects, in the journal BMC Biology.

While most moles have poor eye sight, some can't see at all
   While most moles have poor eye sight, some can't see at all
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