The Good, the Bad, and the Eyeless

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The Good, the Bad, and the Eyeless

By Linda | February 16, 2008

In my last post I described how we measure visual acuity in people. That got me wondering how well human eyesight measures up in the context of the animal kingdom. Here’s what I found out:

The Good

Birds of Prey, such as Hawks and Falcons are believed to have an acuity of around 20/2, which is about eight or nine times better than human eyesight. A Golden Eagle can see a hare from a mile away!

The Bad

Dogs fall somewhere between 20/50 and 20/100, making them up to five times more nearsighted than a 20/20 human. The breed of dog makes a difference, with “sight hounds” such as Greyhounds, Whippets and Salukis having far better distance vision than the average dog.

Domestic Cats possess visual acuity that is 5 to 10 times poorer than that of a 20/20 human in bright light.

Dogs and Cats also have a decreased ability to see objects that are very close to their faces compared to humans. It must be noted however, that Canines, and especially Felines posses much better night vision than we do. Both species also boast far superior auditory (hearing) and olfactory (smell) senses than humans.

The Rhinoceros probably has the worst eyesight of any large animal. From 15 feet it can’t tell a man from a tree and will sometimes charge big rocks.

The Eyeless

During the evolutionary process some species have opted to do away with eyes altogether! Eyeless creatures tend to live in habitats that are devoid of sunlight like the deep ocean, caves and underground aquifers. A few examples of “peeperless” critters are the Golden Mole, and several sub-species of invertebrates including cave dwelling crayfish, shrimp and scorpions.