Lizards & a 3rd eye

Lizards use this patch of light-sensitive cells as a sun-calibrated compass.

A series of clever experiments into the reptilian “third eye” has confirmed that lizards use this patch of light-sensitive cells as a sun-calibrated compass.

To test how third eyes — technically known as parietal eyes — help them find their way, biologists first trained Italian wall lizards to swim from the center of a small outdoor swimming pool to a hidden ledge at its edge. A fence was erected around the pool, so that the only visual point of reference was the position of the sun. The lizards passed the test.