--- title: Study of Injured Squid Explains Human Irritability and Pain description: A new study helps explain the grumpiness and irritability many experience when they are in pain canonical: https://time.com/93539/squid-study-pain-irritability/ author: Michelle Arrouas article:opinion: false article:content_tier: free article:published_time: 2014-05-09T04:31:52.000Z article:modified_time: 2026-02-21T07:44:49.911Z article:section: Science og:title: Study of Injured Squid Explains Human Irritability and Pain og:description: A new study helps explain the grumpiness and irritability many experience when they are in pain og:url: https://time.com/93539/squid-study-pain-irritability/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt7a3a68ff65085792/69868e9c810bbb27d7c917aa/rtr3kh2n.jpg?branch=production&width=800&quality=75&auto=webp&crop=16:9 og:image:width: 800 og:image:height: 450 og:image:alt: A Bigfin reef squid swims in a display at the Monterey Bay Aquarium og:type: article twitter:card: summary_large_image twitter:title: Study of Injured Squid Explains Human Irritability and Pain twitter:description: A new study helps explain the grumpiness and irritability many experience when they are in pain twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt7a3a68ff65085792/69868e9c810bbb27d7c917aa/rtr3kh2n.jpg?branch=production&width=800&quality=75&auto=webp&crop=16:9 ---  # The Study of Injured Squid Explains Human Irritability and Pain > Sponsored content. 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Future Proof is free at time.com/newsletters. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-futureproof-2026q3/newsletters?i=73190d33-51d8-472b-aa3d-6710d7029309&cr=time-nl-futureproof-2026q3-v1) by [Michelle Arrouas](https://time.com/author/michelle-arrouas/) ## Michelle Arrouas May 9, 2014 4:31 AM UTC  A Bigfin reef squid swims in a display for the upcoming "Tentacles: The Astounding Lives of Octopuses, Squid and Cuttlefishes" exhibition at the Monterey Bay Aquarium in Monterey, California, April 8, 2014\. The $3.5 million exhibition, which opens April 12, will feature some species being raised and exhibited for the first time anywhere in the world. REUTERS/Michael Fiala (UNITED STATES - Tags: ANIMALS ENVIRONMENT SOCIETY) - RTR3KH2N A Bigfin reef squid swims in a display for the upcoming "Tentacles: The Astounding Lives of Octopuses, Squid and Cuttlefishes" exhibition at the Monterey Bay Aquarium in Monterey, California, April 8, 2014\. The $3.5 million exhibition, which opens April 12, will feature some species being raised and exhibited for the first time anywhere in the world. REUTERS/Michael Fiala (UNITED STATES - Tags: ANIMALS ENVIRONMENT SOCIETY) - RTR3KH2N Michael Fiala—Reuters by [Michelle Arrouas](https://time.com/author/michelle-arrouas/) ## Michelle Arrouas May 9, 2014 4:31 AM UTC When we are in pain, many of us become grumpy and irritable, and a study involving injured squid may [explain](http://www.latimes.com/science/sciencenow/la-sci-sn-vigilant-squid-and-the-purpose-of-human-pain-20140507-story.html) why. In the [study](http://www.cell.com/current-biology/abstract/S0960-9822%2814%2900335-2), researchers found that squid that have one of their tentacles cut off — an injury that does not affect their ability to maneuver and would not be as serious an injury as losing a limb would be for a human — react more strongly to visual stimuli. The injury also increases the squid’s responsiveness to threats. “The injured squid were really touchy,” Robyn Crook, an evolutionary neurobiologist at the University of Texas Medical School at Houston, which led the study, [told](http://www.latimes.com/science/sciencenow/la-sci-sn-vigilant-squid-and-the-purpose-of-human-pain-20140507-story.html) the Los Angeles _Times_. “An encounter a normal squid might just want to keep an eye on caused the injured squid to start up their defense mechanisms.” The squid’s behavior helps explain the grumpiness and irritability many of us experience when we are in pain, Edgar T. Walters, who studies pain and at the University of Texas Medical School at Houston, [told](http://www.latimes.com/science/sciencenow/la-sci-sn-vigilant-squid-and-the-purpose-of-human-pain-20140507-story.html) the paper. “One of the effects of pain is the peripheral sensory system becomes hyperactive,” he said. “People in pain are very easily irritated and we found that this fits in with a primitive pattern designed for an animal to be extra-vigilant.” ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/93539/squid-study-pain-irritability/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/93539/squid-study-pain-irritability/"},"headline":"The Study of Injured Squid Explains Human Irritability and Pain","datePublished":"2014-05-09T04:31:52.000Z","dateModified":"2026-02-21T07:44:49.911Z","description":"A study has found that squid that have one of their tentacles cut off react more strongly to visual stimuli. 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