Crested Gecko. Photo by author

Saturday, April 16, 2011

Eyes With No Eyelids.

One of the most notable physical appearance geckos of the genus Rhacodactylus are they large round eyes.  These eyes play a large role in their nocturnal lifestyle, in order to stay away from predatory birds in the past (Black).  This noternal eyes will dilate vertically as a slit when coming into contact with any excess amounts of light.  When in dark enviroments its eyes pupils will be more open and much wider.  Having large eyes gives them better motion detecting abilities in detecting prey and predators. 

Rhacodactylus leachianus close up of eye.

Along with having large eyes the entire genus of Rhacodactylus have no eye lids.  Their eye lids are fused together to form a transparent covering, called a ocular scale or eye caps (Black).  Commonly found in snakes, and other nocturnal geckos.  This fused scale acts as protection and a keeps the hydrated.  The tongue is used to keep the eyes clean of debris by licking the eyes. What do you guys think the reasoning nocturnal geckos like Rhacodactylus evolved to possess no eyelids? I think part of it has to deal with that they detect movement constantly weither is a predator or prey so never shutting your eyes gives you faster detecting abilities.

Black, Adam. Crested Gecko. Neptune City: T.F.H. Publications, 2005. Print.

Hague, Bradley. Gecko eye. 2010. Photograph. Web 16 April 2011. http://www.flickr.com/photos/bhague/5060361236/
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2 comments:

  1. gregg flahartyApril 19, 2011 at 10:30 AM

    I had no idea geckos had no eyelids, or that the eyelids they do have are clear and fused together. I agree with what you mentioned about why this feature evolved. It must be to deal with the high number of predators that eat geckos. They would be able to constantly monitor their surroundings even while they sleep.

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  2. KaraApril 19, 2011 at 2:20 PM

    If they did have eye lids wouldn't they have to have some sort of mucus gland of some sort to keep the eye hydrated when blinking? If they have no eyelids it would seem to save energy (from not having the tear gland) and also serve, as you said, as means to watch prey round the clock.

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