| There is something about iguana anatomy that many | | | | The eye serves as the iguana's thermoregulator, or |
| people do not know. The iguana not only has two | | | | thermostat, aiding him in determining when to change |
| eyes on either side of his head, but also a "third" | | | | locations to regulate his body temperature from |
| eye, referred to as the parietal eye. The name | | | | warmer to cooler or vice versa. |
| parietal comes from the fact that the eye is | | | | It is amazing that an iguana can detect a plane or |
| positioned between the raised areas of the parietal | | | | bird overhead in the sky that we may not even |
| bones of the iguana's skull. The third eye is positioned | | | | notice. The third eye is that keen. Iguanas will dodge |
| on the very center top of the iguana's head. | | | | or duck at highway overpasses, bridges, and railroad |
| It is not a cyclops type of an eye, staring up at you | | | | trestles when riding with you in the car. |
| and blinking. It basically appears as a small round scale | | | | Owners should also bear in mind not to suddenly |
| on most iguanas. On a bearded dragon, the third eye | | | | reach from above into the iguana enclosure to pick |
| usually blends in so well with its coloring you can | | | | up your pet because the third eye will alert him to |
| barely see it. This third eye does contain a lens, but | | | | react. For this reason, some people associate the |
| the lens interprets light and darkness, as in shadows | | | | third eye with aggressive behavior. However, it is not |
| and highlights. The parietal eye lens does not | | | | the third eye causing this aggression. The iguana just |
| "process" shapes, images, or colors. Actually it is not | | | | instinctively feels threatened or launched into a higher |
| an eye at all, but a light and energy monitor to | | | | awareness that something is afoot because of the |
| indicate environmental changes from overhead. The | | | | light and shadow changes and the sudden detection |
| eye serves as the iguana radar motion detector, in a | | | | of movement. |
| sense. | | | | It is also believed that the third eye has some effect |
| Most all of us have heard the phrase "sleeping with | | | | on the breeding behavior of iguanas. It is known to |
| one eye open." That is pretty much what an iguana | | | | be associated with triggering hormone production. |
| does. In the wild, when an iguana basks in the sun, | | | | There are still some questions as to all of the |
| the third eye easily detects changes in the highlights | | | | purposes and functions of the iguana parietal eye. As |
| and shadows of the environment. These changes in | | | | more research and study is performed, hopefully |
| light can indicate danger, a predator, or simply that it | | | | more facts will be revealed. |
| is time for the iguana to move from sun to shade. | | | | |