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Which animal has the best eyesight? - Thomas W. Cronin


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TEDEd Animation

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The animal kingdom boasts an incredible diversity of eyes. Some rotate independently while others have squiggly-shaped pupils. Some have protective lids, others squirt blood. But which creature has the best sight? Which sees best in the darkness? Which sees the most detail? Which animal sees the most color? And finally, which detects motion the fastest? Thomas W. Cronin investigates.

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Humans depend primarily on their vision for continuous information about the world around us. Almost everyone assumes that human vision is the best – we see the sharpest detail, we have the best color vision, and we can track the flight of a 100-mph fastball, and so on. So, it’s a surprise to learn (as you saw in this video) that we are bettered by one or another animal in all regards. You probably knew that there are animals that see better in the dark and that it’s hard to swat or catch a fly, but most people have no idea that our color vision is rather limited or that some animals would see the bottom line on an eye chart as clearly as a newpaper headline! And to rub salt in the wound, there are animals that see light and colors that are totally invisible to us, like ultraviolet light or polarized light. Also, most people think that the tiny eyes of animals like fruit flies or mice are nearly useless compared to ours, but they meet the needs of these animals precisely.

Studying the science of vision is made easier because every known eye relies on a light-sensing pigment (called a “visual pigment”), based on a protein called “opsin”, and all opsins are evolutionarily related and operate in essentially the same way. Besides this, all eyes are limited by the fundamental laws of physics, so optical principles always apply. Given the current diversity of eye types, it’s not surprising to learn that modern eyes probably evolved independently many times, but still have similar optical and visual pigment properties. 

The study of how animal eyes have evolved and how they provide all the information needed by a particular animal inhabiting a particular environment is called “visual ecology”. Most of the information in the Ted-Ed video was discovered by visual ecologists. They work with visual systems mostly out of their own curiosity, and their research almost always fascinates most people with even a remote interest in science or animal vision. A recent example is the production “Life in Color”, done by 95-year-old David Attenborough. Other popular video accounts can be found on YouTube or The Atlantic. If you have access to Curiosity Stream, you can also see the more detailed account, “What Animals See”.

The research of visual ecologists is not only important because it is interesting and informs us about the world we live in. It also is used by imaging engineers to design new sensors and cameras, for underwater navigation or to assist in finding newly developing cancer cells.

Humans have eyes that do well in many ways, giving us an excellent “picture” of what’s happening in our surroundings. Overall, they are outstanding examples of evolutionary compromise, so that we are as well-informed about the natural world as we need to be. Yet, we have learned here that many animals – even ones as seemingly simple as houseflies - outperform us in various critical aspects of vision. We should wonder what other surprises the study of animal vision will bring us. 

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Meet The Creators

  • Educator Thomas W. Cronin
  • Director Josefina Preumayr
  • Narrator Addison Anderson
  • Animator Josefina Preumayr, Jasmine Lister
  • Compositor Josefina Preumayr
  • Art Director Josefina Preumayr
  • Composer André Aires
  • Sound Designer André Aires
  • Director of Production Gerta Xhelo
  • Editorial Director Alex Rosenthal
  • Producer Bethany Cutmore-Scott
  • Associate Editorial Producer Cella Wright
  • Script Editor Alex Gendler
  • Fact-Checker Jennifer Nam

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