What Is a Parietal Eye?

Parietal eye can be found in some frogs.

Parietal eye is an organ found in some species of animals as a third eye in a segment of the middle part of the brain. Sometimes it is called parietal organ or third eye.

Features

The parietal eye is usually covered by skin, is usually not visible externally and is usually much smaller than the other two eyes. In some species, the parietal eye actually breaks through the skin.

Species

Species that can develop parietal eyes include lizards, frogs, some fish, pelagic sharks, aquatic mammals and even some types of birds.

Identification

In most cases, the parietal eye can be identified by finding a small, grey oval between the other eyes.

Function

The parietal eye is usually associated with the pineal gland, which develops sleep patterns and helps regulate a 24-hour life cycle.

Effects

Parietal eyes cannot see as normal eyes do, but they can detect light and dark, which enables some sensory capabilities. A parietal eye has a small lens and retina.

References

• Victoria University of Wellington: Parietal Eye
• Melissa Kaplan's Herp Care Collection: The Parietal "Eye"
• Absolute Astronomy: Parietal Eye

Resources

• Science Daily: Lizard 'Third Eye' Sheds Light on Evolution of Color Vision