• Posted on January 18, 2013 8:28 pm
    By Chris
    Crabs Feel Pain Too

    Today’s Diary Entry is sponsored by Spikes World

    One of the areas I am passionate about is animal welfare, with previous research into animal pain and suffering as I believe alleviating this is key to a better world. I tend to try and keep track of what is happening with the latest research coming out etc. Back in March 2012 I was aware of research into the ability of hermit crabs to learn, today however I came across new research into the ability of crabs to feel pain.

    Crabs Feel Pain TooNow its always been accepted that as shellfish have a primitive central nervous system (CNS) they could not feel pain and so they are just cooked alive in boiling water. The response seen when they are dunked into boiling has always been labelled as a reflex response and not one of pain-induced self preservation. It has been argued for many years that the way crustaceans (crabs, lobsters etc) are banded and stored before being cooked in boiling water causes tremendous pain, yet the problem has been how to prove this.

    The problem here is that it is philosophically impossible to demonstrate an animals ability to feel pain. The best we can do is develop a set of criteria of what we would expect to see if an animal was in pain (vets use this principle all the time!) and so the research proposal came together. Researchers at the Queens University Belfast School of Biological Sciences devised an experiment to test whether crabs felt pain. I’ve decided that the researcher Bob Elwood at the university described the experimental process best so have him explaining it to you:

    Elwood described how it went: “Ninety crabs were each introduced individually to a tank with two dark shelters. On selecting their shelter of choice, some of the crabs were exposed to an electric shock. After some rest time, each crab was returned to the tank. Most stuck with what they knew best, returning to the shelter they had chosen first time around, where those that had been shocked on first choice again experienced a shock. When introduced to the tank for the third time, however, the vast majority of shocked crabs now went to the alternative safe shelter. Those not shocked continued to use their preferred shelter.”

    He continued, “Having experienced two rounds of shocks, the crabs learned to avoid the shelter where they received the shock. They were willing to give up their hideaway in order to avoid the source of their probable pain.”

    Now one of the criteria used in determining pain is that animals will learn to avoid pain, or try to reduce the pain they are in (hence the praying position in dogs, or effectiveness of electric fences with horses). Under this principle it appears that the crabs that experienced the electric shock (which were relatively mild so as not to cause permanent harm) gave up their safe shelter to hide somewhere else in order to avoid the painful stimuli. In fact as anyone that has ever cooked a lobster or crab will know, it does not just sit still in the pan but will go into a frenzy.

    Research is increasing starting to show that though we look different, pain is a feeling that is shared between all species. As an advocate for animals it is important that we consider the pain of all animals, and not just those that are cute and cuddly!

    Posted in categories: Vet School Diary
  1. Rawda Elsayed

    I love this research that has been made. Actually it would help for my research project I am currently working on right now. Would you by any chance know how to MEASURE this pain, other than behaviour in the crab can you find out how to maybe measure their reactions to the shock by heart rate or respiratory rate. I would really appreciate it if you reply back with some help. Thank you in advance!


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