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For a new study, which the journal Trends in Ecology & Evolution recently published, a team of researchers set out to discover what the world looks like through the eyes of animals. According to lead author Eleanor Caves, humans see a lot better than most critters in the animal kingdom. They are not able to distinguish as many details as we do. Recently, scientists have been trying to find out just how clear or how blurry animals see, in comparison to humans.
So, in order to find out more about this fascinating topic, the team of experts compiled estimates of visual acuity for 600 different species. This list included mammals, birds, fish, insects, and even crustaceans. Caves explains that for humans, the classic measure is equal to the size of one’s thumb when the arm’s extended. Like this, humans can reportedly see 60 cycles, or lines, as they are also called, per degree. The same system works for animals too. However, in order to determine the cycles per degree of a certain species, experts measured the density of their photoreceptors, which can be found in their retina.
How clear or blurry animals see
The idea is simple: as the measure decreases, the quality of one’s vision also does. For example, at less than 10 cycles per degree, a human can be deemed blind. However, when it comes to insects, some of them are lucky if they can see one cycle per degree. And to exemplify what big differences there are in the animal kingdom, the wedge-tailed eagle can see 140 cycles per degree. Cats see less than 10 cycles per degree, which is not very much at all.
After using the software program called AcuityView, researchers were able to see how different animals see. Less cycles translated into blurry views. This is why birds see and avoid spider webs while flies or other insects fall right into it.
Image source: pixabay
