Extending the Animal Welfare Act 2006 to include lobsters, crabs and other crustaceans


The Animal Welfare Act 2006 states that its protection can be extended to other types of animals if it can be proven that they are capable of experiencing pain.* There is as much scientific evidence to suggest that, at the least, the decapod crustaceans (lobsters, crabs, prawns and crayfish) experience pain, as there is to suggest that animals already protected by the Act experience pain (see below). Since the principle of consistency is central to our legal system, we urge that protection be extended to these animals, too.

The importance of extending legal protection to decapod crustaceans

Catching, trapping, handling, holding, storing and killing can cause injury, stress and suffering to decapod crustaceans. During these processes they may suffer infections, open wounds and other lesions. They may die from starvation, dehydration, overheating, or from injuries sustained from fighting whilst in unattended storage pots or lost traps.

Storage and killing in restaurants, retailer and domestic environments are not yet regulated. The current practice of killing lobsters by cooking them alive in boiling water without the use of anaesthesia or pre-stunning is of particular concern. The animals struggle violently, even shedding their limbs or tearing at their own bodies with their claws. It is no longer acceptable to assume that this behaviour is reflex and involves no pain.

Additionally, eyestalk ablation in prawns and shrimps – the removal of the eyestalk, which triggers the maturing of the ovaries – is accepted by scientists to be both ‘controversial’ and ‘cruel’.1 One Mexican researcher described eyestalk ablation as ‘traumatic’.2

The RSPCA, Viva, Animal Aid, the Shellfish Network and other animal welfare organisations are calling for greater protection for these animals, based on sound scientific evidence and the provision in the Act.

The scientific justification for including decapod crustaceans under the Animal Welfare Act

There is plentiful evidence that crustaceans are capable of experiencing pain, which is a requirement for a regulation to be made under the Act. There is also evidence that they do, indeed, experience pain – a higher test than is required for them to be granted legal protection.

Since pain and suffering are private, internal experiences, they are difficult to prove beyond doubt even in animals who are covered by the Animal Welfare Act or, indeed, in humans other than ourselves. Scientists, therefore, seek to determine that the animals are both capable of feeling pain because they have nervous systems and related physiological and neurochemical mechanisms, and that they give some behavioural indication that they do feel pain (such as through avoidance or escape). Having the mental capacity to learn from, remember and respond to noxious stimuli is also key in determining whether crustaceans feel pain.

Decapod crustaceans are capable of feeling pain

The nervous system of decapod crustaceans consists of nerve cords running along their bodies connecting ganglia, or concentrations of nerve cells that are almost like small brains and which function as centres for reception of sensory inputs.3 The animals have a large number of receptor cells for detecting chemical and mechanical inputs, and have compound eyes that cover a wide field and are connected by nerves to the brain. Decapod crustaceans are well equipped to be informed of their surroundings and the internal state of their bodies.4

Crustaceans have the sensory receptors – nociceptors – necessary to respond to aversive or noxious stimuli, and these send signals to the brain, which cause the perception of pain. Nociception has been described as a ‘basic characteristic of animals’,5,6 without which they could not survive. Nociception is a reflex phenomenon and, therefore, different to pain. However, nociception is the physiological process underlying pain. (The function of pain is to aid future avoidance of the pain source, whereas nociception enables a reflex response that provides immediate protection but no awareness or changes to long-term behaviour. While we do not rely solely on the presence of nociceptors in our evidence that crustaceans feel pain, they do add to the evidence that decapods have the capacity to feel pain.)

Decapod crustaceans have very similar physiological and neurochemical responses to stimuli that would be expected to cause pain to vertebrates. In humans and other vertebrates, for example, opioids that are produced in the body can modify the nervous transmission of nociception and reduce pain. 7,8,9,10 Opioid peptides – enkephalins – have been found in decapod crustaceans, and appear to have a similar role as in vertebrates, strongly suggesting that they mediate pain in the same way. Experimenters assume explicitly that an electric shock is a ‘painful stimulus’ to a crab, and studies have concluded that the fact that crabs show a reduction in reaction to shocks could be due to an analgesic effect produced by endogenous opiates.11

Various studies over many years have found that crabs exhibit a defensive reaction to electric shocks, and that this reaction can be reduced by administering morphine (which, in turn can be counteracted by naloxone, an opioid antagonist). A 1988 experiment showed that morphine reduced crabs’ sensitivity to electric shocks by 50 per cent, and that the effects were dose-dependent.12 A 1992 experiment found similar results by striking the crab between the eyestalks.13 A 2011 study, however, suggested that the morphine produced an effect of non-responsiveness, rather than a specific analgesic effect.14 Despite this, the researchers urged caution in interpreting these results: ‘we question the utility of this criterion of pain and suggest instead that behavioural criteria be employed.’15

In other words, crustaceans have the capacity to feel pain, but whether or not they actually do experience pain should be determined through behavioural studies.

Behavioural indication that crustaceans feel pain, and remember it

Professor Robert Elwood is a world expert on the experience of pain in crustaceans. He writes: ‘Pain is a strong negative motivation and enhances avoidance learning for long term protection. Coupled with this is discrimination learning – if animals simply avoid everything they will miss positive opportunities.’16

Prof. Elwood believes that there are three key behavioural criteria to discriminate pain from nociception:

  • Avoidance learning
  • Motivational trade-offs
  • Prolonged directed rubbing

In January 2013, the details of an experiment conducted by Prof. Elwood and Barry Magee from Queen’s University School of Biological Sciences were made public via the Journal of Experimental Biology. Ninety common shore crabs had been given electric shocks when they entered one shelter but not another. Prof. Elwood said: ‘Crabs value dark hideaways beneath rocks where they can shelter from predators. Exploiting this preference, our study tested whether the crabs experienced pain by seeing if they could learn to give up a valued dark hiding place in order to avoid a mild electric shock. 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. They were willing to give up their hideaway in order to avoid the source of their probable pain.’ 17

Prof. Elwood, in another experiment, introduced hermit crabs to either good quality shells or poor quality shells, and then also subjected them to electric shocks. More hermit crabs exited the poor quality shells when shocked than the good quality shells, indicating that the animals made a trade-off between being shocked and staying in a better shell. This experiment indicates there is a motivational trade-off, the second criteria Prof. Elwood indicates differentiates pain from nociception.

And in a third experiment, glass prawns were found to groom their antennae substantially more when noxious substances were applied to them or when they were pinched with forceps, than when they were treated solely with sea water. The researchers found that the application of a local anaesthetic reduced the grooming following the chemical applied.18

The European Food Safety Authority, a well-respected body which provides independent scientific advice on food safety risks to the European Commission, supports the need for decapods to be protected. In its 2005 Opinion on the ‘Aspects of the biology and welfare of animals used for experimental and other scientific purposes’, it writes: ‘The largest of decapod crustaceans are complex in behaviour and appear to have some degree of awareness. They have a pain system and considerable learning ability. As a consequence of this evidence, it is concluded that cyclostomes, all Cephalopoda and decapod crustaceans fall into the same category of animals as those that are at present protected…’ They recommended that ‘[a]ll decapods should be in Category 1 (see Section 2.5) and so receive protection.’ 19

Extending the Animal Welfare Act

Currently, the Act offers protection only to vertebrates. It does allow, however, the appropriate national authority to make regulations to extend the Act to include ‘invertebrates of any description’ if it is satisfied on the basis of scientific evidence that the animals concerned are ‘capable of experiencing pain’.

We believe that the case for decapod crustaceans being both capable of feeling pain and experiencing pain is convincing. Even if the law demanded that the higher bar was reached, we would urge the authorities to take a precautionary approach and amend the Act on the balance of evidence. However, the Act demands the less stringent criterion: that crustaceans are merely capable of experiencing pain.

Since there is as much evidence to indicate pain in decapod crustaceans as there is for other animals already covered by the Act, we urge that consistency is shown to all animals capable of experiencing pain, and that the Animal Welfare Act 2006 is amended to include decapod crustaceans.

June 2014


* (3) The appropriate national authority may by regulations for all or any of the purposes of this Act—
(a) extend the definition of “animal” so as to include invertebrates of any description;
(b) make provision in lieu of subsection (2) as respects any invertebrates included in the definition of “animal”;
(4) The power under subsection (3)(a) may only be exercised if the appropriate national authority is satisfied, on the basis of scientific evidence, that animals of the kind concerned are capable of experiencing pain or suffering.


  1. Humane technique for black tiger shrimp farming devised by Mahidol researcher, Mahidol University press release, 1 Aug 2012.
  2. AQUA 2012: Minimising Pain of Eyestalk Ablation in Freshwater Prawn, 6 Sept 2012
  3. L S Sømme. Sentience and pain in invertebrates. Report to Norwegian Scientific Committee for Food Safety. Norwegian University of Life Sciences (2005)
  4. L S Sømme. Sentience and pain in invertebrates. Report to Norwegian Scientific Committee for Food Safety. Norwegian University of Life Sciences (2005)
  5. M Kavaliers. Evolutionary and comparative aspects of nociception. Brain Research Bulletin 21:923-932(1988)
  6. J A Smith. A question of pain in invertebrates. Institute for Laboratory Animal Research (ILAR) Journal online 33(1-2) (1991)
  7. M Kavaliers. Evolutionary and comparative aspects of nociception. Brain Research Bulletin 21:923-932 (1988)
  8. C M Sherwin. Can invertebrates suffer? Or, how robust is argument-by-analogy? Animal Welfare 10:S102-118 (2001)
  9. J A Smith. A question of pain in invertebrates. Institute for Laboratory Animal Research (ILAR) Journal online 33(1-2) (1991) http://dels.nas.edu/ilar/jour_online/33_1_2/V33_1_2Question.asp
  10. G Fiorito. Is there ‘pain’ in invertebrates? Behavioural Processes 12:383-388 (1986)
  11. C Valeggia, D Fernandez-Duque and H Maldonado. Danger stimulus-induced analgesia in the crab Chasmagnathus granulatus. Brain Research 481(2):304-308 (1989)
  12. M Lozada, A Romano and H Maldonado. Effect of morphine and naloxone on a defensive response of the crab Chasmagnathus granulatus. Pharmacology Biochemistry and Behavior 30(3):635-640 (1988)
  13. P Bergamo, H Maldonado and A Miralto. Opiate effect on the threat display in the crab Carcinus mediterraneus. Pharmacology Biochemistry and Behavior 42(2): 323-326 (1992)
  14. S Barr, RW Elwood. No evidence of morphine analgesia to noxious shock in the shore crab, Carcinus maenas. Behav Processes 2011 Mar;86(3):340-4. doi: 10.1016/j.beproc.2011.02.002. Epub 2011 Feb 13.
  15. Ibid
  16. R Elwood, The evidence for pain in crustaceans, ILAR Journal 52, 175-184
  17. ‘Shell-shocked’ crabs can feel pain, Queen’s University media release, 14 January 2013
  18. S Barr et al (2008) Animal Behaviour 75, 745-751
  19. Opinion on the Aspects of the biology and welfare of animals used for experimental and other scientific purposes, The EFSA Journal (2005) 292, 1-46