Cats and dogs may see in ultraviolet

When your cat seems to be staring at nothing it could actually be seeing something that is invisible to the human eye. 

New research suggests cats and dogs can see in ultraviolet, LiveScience reported. 

"Nobody ever thought these animals could see in ultraviolet, but in fact, they do," study leader Ron Douglas, a biologist at City University London told LiveScience. 

Humans are able to see many colors of light, but ultraviolet (UV) light is not detectable. Animals such as birds, bees, reptiles, amphibians and fish are already believed to posses UV vision; some mammals such as mice have been suspected of having it as well. 

The lens of the human eye blocks UV light, humans who have had this lens removed have reported being able to see the UV light.

Some animals have a UV-transparent lens.

Researchers collected eyes from a wide variety of animals and measured how much UV light the lens allowed in. 

They found "hedgehogs, dogs, cats, ferrets and okapis" all have lenses that allow UV light to pass through, LiveScience reported

The researchers wanted to know what the benefit is of being able to see UV light. 

"The question is only being asked because humans can't see it," Douglas told Live Science.

It is believed seeing the light helps bees find pollen, deer spot hungry polar bears, and rats follow urine trails. 

Douglas believes the question to ask is "why do human eyes block out UV light.

The researcher believes blocking out UV light helps sharpen vision, like a skier wearing yellow goggles. The animals that blocked out UV light were found to possess the sharpest vision. 

Humans have many cones in their retinas which allows them to "produce high-quality images with just a small amount of light," LiveScience reported. Nocturnal animals have eyes designed to allow as much light in as possible. 

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