Non-Nocturnal Snakes have 'Sunglasses' that Block Out UV Rays, Sharpen Vision

Snakes that usually hunt in daylight are found to have UV-filtered lenses that can also sharpen their vision.

According to a new research published in the journal Molecular Biology and Evolution, there are new ideas about the relationship between ultraviolet (UV) filters and hunting methods in snakes, EurekAlert reports.

It turns out that snakes adjust their vision. During the day, some snakes' eye lenses act as "sunglasses" that filter ultraviolet light and in turn sharpen their vision. Meanwhile, snakes that hunt at night have eye lenses that do not filter ultraviolet light but, instead, let it pass through so that they can see more while in the dark.

Snakes have highly variable sets of rods and cones. These specialized cells in the retina help to spot light.

How about seeing different colors? For animals, they have visual pigments in their rods and cones to use that are sensitive to different light wavelengths.

It was also discovered that most of the snakes have three visual pigments, making them see two primary colors in daylight, unlike humans that can see three.

The same study of 69 snake species also determined that snakes have adjusted to adapt to the challenges of their surroundings by examining their visual pigment genes, which have gone through many changes.

Mirror also reported that even though most of the snakes were sensitive to ultraviolet light that made them see better in low-light conditions, snakes that hunted during the bright daylight had lenses that blocked UV light such as the gliding golden tree snake (Chrysopelea ornata) and Montpellier snake (Malpolon monspessulanus). Meanwhile, nocturnal snakes don't have eyes that can filter UV light.

This new research was an international collaboration between snake biologists and vision experts led by David Gower and included fellow Natural History Museum researchers Bruno Simões and Filipa Sampaio.