Ea­gles are the most sharp-sighted an­i­mals

A new com­puter gives zo­ol­o­gists an idea of the vi­sion of dif­fer­ent an­i­mals.

Science Illustrated - - SCIENCE UPDATE -

The hu­man eye is not the best at dif­fer­ing be­tween colours nor see­ing in the dark, but in one way, we are the most ex­cel­lent: sharp­ness. Sci­en­tists from the Duke Univer­sity in the US have de­vel­oped a com­puter pro­gramme that sim­u­lates an­i­mal vi­sion and tested it on 600 species.

The sharp­ness is de­fined as pe­ri­ods per de­gree, or how many pairs of black and white lines the eye can make out within one de­gree of vi­sion. The hu­man eye has a res­o­lu­tion of 60 pe­ri­ods per de­gree, and if the lines are more densely packed, they will merge into a grey mass. The sci­en­tists eval­u­ated the an­i­mal vi­sion based on anatomy and en­tered the data into the com­puter pro­gramme which, well, vi­su­alises the vi­sion of dif­fer­ent crea­tures.

Most species have poorer vi­sion than we do. Most fish and birds have a vi­sion of about 30 pe­ri­ods per de­gree, but for many in­sects, the num­ber is about 1. Pri­mates see just as well as we do, and only a few birds of prey have sharper vi­sion. The "winner" of the study was the wedge-tailed ea­gle, which can see 140 pe­ri­ods per de­gree.

One in­ter­est­ing find­ing: But­ter­flies can­not see the pat­terns on their own wings. In­stead, the pat­terns scare off sharp-sighted en­e­mies.

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