The moral status of crustaceans: Where are we?

Posted on 31 January 2018 by

Gemma Carder

in the Animal sentience blog

Research exploring the inner lives of crustaceans is growing. The implications for animal welfare legislation are discussed here by Gemma Carder.

Currently, research exploring the emotional lives of animals is exploding. We know a great deal about vertebrates and are starting to learn more about invertebrates. In light of this, evidence is telling us that we should be moving away from the assumption that only vertebrates experience pain and have the ability to suffer. In this blog, I will outline some of the science supporting that crustaceans experience pain, and what I think should mean for their protection.

What does science tell us?

Assessing whether or not certain groups of animal’s experience pain can be complicated, because it is often hard to distinguish between pain and nociception. The main difference between the two is that pain helps the individual avoid future harmful events. On the other hand, nociception is a reflex response, protecting the individual from immediate danger, but there is no long term awareness or change in behaviour.

For a number of years Professor Robert Elwood, Queen’s University Belfast, has led on pioneering research exploring pain in different crustacean species. To briefly summarise, one study found that when acetic acid was put on the antenna of prawns, they would rub the infected antenna [1]. Hermit crabs value their shells, and they are vital for their survival. When hermit crabs were housed in their preferred and unpreferred species of shells, and given small electric shocks, those housed in their preferred shells only evacuated after receiving a higher shock level, compared to those in their unpreferred shells, which left more quickly [2].  This trade off with retaining their high quality shell and avoiding the shocks are consistent with experiencing pain rather than nociception [2,3].

Now that we have findings demonstrating that it is likely that crustaceans do feel pain, we can hopefully begin to move away from studies which cause suffering towards less invasive research.

Watch this video to find out more about the research.

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Legal protection?

Billions of crustaceans are inhumanly slaughtered each year, often being frozen and boiled alive. Currently crustaceans have very little legal protection. Animal protection legislation is hugely biased towards vertebrate species; this is largely based on the assumption that invertebrates are incapable of suffering. One of the few exceptions is the New Zealand Animal Welfare Act (1999) which defines ‘animals’ as a live mammal, bird, reptile, amphibian, fish or octopus, squid, crab, lobster or crayfish.

Changing perceptions

Changing legislation is vital, but public perceptions also need to change. This is where robust scientific evidence supporting pain in crustaceans can be very powerful. If used in the right way the evidence can help drive the public to feel compassion and have respect for all those lobsters, crabs and other crustaceans being forced to suffer every day. And perhaps one day we will have science to show that actually invertebrates also experience other emotions too far beyond pain.

In conclusion, the science is there, supporting a likely assumption that crustaceans can suffer. We have a long way to go in changing public perceptions and gaining legal protection for crustaceans, but in my opinion we should be giving crustaceans the benefit of the doubt and this should be reflected in animal protection legislation.

Further reading

[1] Elwood, R. W.; Barr, S.; Patterson, L. Pain and stress in crustaceans? Appl. Anim. Behav. Sci. 2009, 118, 128–136.

[2] Appel, M.; Elwood, R. W. Motivational trade-offs and potential pain experience in hermit crabs. Appl. Anim. Behav. Sci. 2009, 119, 120–124.

[3] Elwood, R. W. Evidence for pain in decapod crustaceans. Anim. Welf. 2012, 21, 23–27.

Gemma Carder is a member of the Crustacean Compassion campaign group:

Read Gemma's paper on lobster welfare, published by Crustacean Compassion, here: Carder, Gemma (2017) A preliminary investigation into the welfare of lobsters in the UK.

Sign the Crustacean Compassion petition asking the government to recognise crustacean sentience in the Animal Welfare Bill here:

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