Learn how animals see the world

Despite the importance of all five senses, vision plays a predominant role in our lives. Even though animals generally use other ways of interacting with the world, there is always curiosity about how they view objects.

By compiling data from several studies, scientist Eleanor Caves of Duke University in the United States has been able to analyze approximately 600 species of birds, mammals, fish and other animals. The aim of the research was to determine their ability to see the world and what their vision would look like through our eyes.

Standardized Method

The measure used for the comparison was the number of cycles per degree, that is, the number of parallel black and white lines an animal can see in one degree of its field of vision. Caves explained to Live Science that equivalence is the size of a thumb when the arm is fully extended. A human with no problem in this area visualizes 60 cycles, or lines.

To determine how much each species sees, we observed the density of photoreceptors present in each other's eyes. In some cases, behavioral experiments were conducted, analyzing the animals' awareness of the presented stripes.

The fewer of these traits identified, the worse the eye equipment is. Ours is not the best in the food chain, but we do the job relatively well. A person who does not have a capacity greater than ten cycles per degree can be considered nearly blind, but an insect that recognizes one can already consider itself lucky.

Comparisons

Australia's largest bird of prey, the daring eagle, can identify an amazing 140 cycles per degree, accurate enough to find a rabbit while flying. Cats and dogs only see 10, but the difference with felines is that they have a very good perception of color and light, favoring dark vision. Small shrimp, common in aquariums, see only 0.1.

After compiling the data, they were loaded into software called AcuityView, developed by the researcher herself. The program uses a photo as a reference and simulates what would be the view of each species, based on the measurement of cycles by degree. The smaller the values, the more blurred the images.

The results show, for example, that a bird can identify a spider's web in time to deflect during flight, unlike a fly, which ends up falling into the trap. In the image below, on the left, is represented as a bird sees a butterfly, and on the right, as they see each other.

Although illustrative to us, the images do not correspond exactly to how stimuli are interpreted by animals. According to Caves, there are influences affecting this process. For us, this level of vision may be totally useless, but the researcher explains that “the software only shows what information is available. You cannot use data you have never received; that is, if accuracy is insufficient to identify any detail, it is probably something the brain would not be able to handle. ”

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