Scientists confirm: Hurt crabs feel pain

And try to avoid it

BELFAST–Hermit crabs feel pain when injured and change their behavior to avoid the source of pain,  reported Robert Elwood of the School of Biological Sciences at Queen’s University in Belfast,  Northern Ireland,  on March 27,  2009.

“With vertebrates we are asked to err on the side of caution and I believe this is the approach to take with crustaceans,”  concluded Elwood.

“Practices may warrant reassessment”

“Ripping the legs off live crabs and crowding lobsters into seafood market tanks are just two of the many practices that may warrant reassessment,”  warned Jennifer Viegas of the Discovery Channel.

More than 4,130 news web sites amplified Elwood’s findings,  soon to be published in the journals Animal Behavior and Applied Animal Behavior Science.

The hermit crab study was Elwood’s second well-publicized attempt to establish to the satisfaction of most remaining scientific skeptics that crustaceans feel pain.   New Scientist in November 2007 published Elwood’s findings about the behavior of 144 prawns after he daubed one of their antennae with a solution of diluted acetic acid.  The prawns immediately groomed and rubbed the daubed antennae,  but not their other antennae.  This,  Elwood wrote,  was “consistent with an interpretation of pain experience.”

“Blow for fans of boiled lobster”

The Guardian headlined a report about the prawn study “Blow for fans of boiled lobster.”

But other researchers alleged fault with Elwood’s experiment.

“Even a single-cell organism can detect a threatening chemical gradient and retreat from it,”  University of Utah pain researcher Richard Chapman told Guardian reporter Ian Sample.  Elwood designed the hermit crab study to respond to the criticisms of the prawn study.  He and colleague Mirjam Appel collected hermit crabs from rock pools in County Down,  Northern Ireland.

“All of the crabs survived the experiments and were later released back into their native habitat,”  reported Viegas.  Hermit crabs,  rather than forming their own shells,  occupy shells discarded by other animals.  Once they find a satisfactory shell, they are reluctant to abandon it.  Their usual response to a threat is to retreat farther into the shell.

Alternative shells

Elwood and Appel offered the hermit crabs alternative shells to move into,  but shells less attractive to them than the shells they already had.

Elwood and Appel then gave some of the crabs small electric shocks while they were inside their old shells.  They also groomed themselves in a manner that Elwood and Appel described as “a protective motor reaction,  viewed as a sign of pain in vertebrates.”  Crabs who were not shocked did not take the opportunity to change shells.

“There has been a long debate about whether crustaceans including crabs, prawns and lobsters feel pain,”  Elwood summarized in a media release.  “We know from previous research that they can detect harmful stimuli and withdraw from the source of the stimuli but that could be a simple reflex without the inner ‘feeling’ of unpleasantness that we associate with pain.  This research demonstrates that it is not a simple reflex but that crabs trade their need for a quality shell with the need to avoid the harmful stimulus.”

Trade-offs

“Such trade-offs are seen in vertebrates,”  Elwood wrote,  “in which the response to pain is controlled with respect to other requirements. Humans,  for example,  may hold  a hot plate that contains food,  whereas they may drop an empty plate,  showing that we take into account differing motivational requirements when responding to pain.

“Trade-offs of this type have not been previously demonstrated in crustaceans,”  Elwood continued.  “The results are consistent with the idea of pain being experienced by these animals.”  Elwood spoke specifically to the treatment of crustaceans by the seafood industry.

“More research is needed in this area where a potentially very large problem is being ignored,”  he said.  “Legislation to protect crustaceans has been proposed [in Britain] but is likely to cover only scientific research.  Millions of crustaceans are caught or reared in aquaculture for the food industry.  There is no protection for these animals,  with the possible exception of certain states in Australia.”

Seven reasons for believing that crustaceans suffer

In Elwood’s Applied Animal Behavior Science paper,  he and co-authors Stuart Barr and Lynsey Patterson cite seven reasons for believing that crustaceans suffer.  In addition to the findings of the hermit crab and prawn experiments,  they explain,  crustaceans placed under stress demonstrate physiological changes consistent with feeling pain,  including release of adrenal-like hormones.  If crabs are given anesthetics or  analgesics,  they appear to feel relieved, showing fewer responses to negative stimuli.

Contrary to the supposition that having a brain is necessary to feel pain,  Elwood et al argue,  crustaceans have “high cognitive ability and sentience.”

Feelings of pain and stress in mammals are associated with the neocortex.  Because crustaceans lack a neocortex,  prevailing belief until recently was that they lack the physiological structure necessary to suffer.

Analogy to vision

Responds  Elwood,  “Using the same analogy, one could argue crabs do not have vision because they lack the visual centers of humans.”

In fact,  fish,  lobsters and octopi all have vision,  and some species have relatively advanced vision,  despite lacking a visual cortex.  The explanation is that their neurological systems are organized in a different manner,  with different control structures.”It was also thought,”  said Viegas of the Discovery Channel,  “that since many invertebrates cast off damaged appendages,  it was not harmful for humans to remove legs,  tails and other body parts from live crustaceans.

Another study led by Lynsey Patterson,  however, found that when humans twisted off legs from crabs,  their stress response was so profound that some later died.”

Humane response

Much of the humane community has believed for decades that the treatment of crustaceans should become a topic of urgent concern–if only to avoid practices that might encourage callous treatment of other species.  In 1952,  for example, delegates from 25 nations agreed at a convention hosted by the World Federation for the Protection of Animals–one of the three ancestors of the World Society for the Protection of Animals– that boiling live crustaceans sets a bad example of how animals should be treated,  and should be abolished.

PETA has staged heavily publicized live lobster releases almost annually for more than 25 years.  In 2006 two members of Animal Rights Croatia locked themselves into a fish tank to dramatize the fate of lobsters.

Advocates for Animals

Serious efforts have also been made by the humane community to assemble scientific evidence that crustaceans suffer.  The Scottish organization Advocates for Animals in 2005 published a volume entitled Cephalopods & Decapod Crustaceans:  Their Capacity To Experience Pain & Suffering,  assessing all that was known at that time.

Such efforts have brought some results.

Notably,  the grocery chain Whole Foods in 2006 quit selling live soft-shelled crabs and lobsters for humane reasons.

But the humane community has also been embarrassed by incidents such as a crab cook held in 2005 to benefit the Prince Rupert SPCA.  A sequel was cancelled in 2006 by the British Columbia SPCA,  parent organization to the Prince Rupert SPCA,  after Sea Shepherd Conservation Society founder Paul Watson led a campaign against it.

Concern for fish

Concern about crustacean suffering is rising parallel to campaigns on behalf of fish.  Hong Kong SPCA executive director Sandy Macalister,  for instance,  editorialized recently in the membership magazine Paw Prints against the practice of restauranteurs keeping giant groupers and other species on display in cramped tanks,  until bought and killed for someone’s dinner.

“These wonderful animals,  which since the 1940s have lived and bred in the coral depths,  now lie behind thick distorting glass in a narrow tank on the footpath,”  wrote Macalister.  “How many times have we walked past such horrific living conditions for these animals without a second thought?  Is it because we consider them to be `just fish’?  If a passer-by or a restaurant patron knew that these magnificent creatures were more than 65 years old,  would that make a difference?”

“Fish are vertebrates like us”

Macalister’s editorial attracted extensive sympathetic coverage from Simon Parry of the South China Morning Post.

“Fish are vertebrates like us,” University of Hong Kong biologist Yvonne Sadovy told Parry.  “They have a backbone,  and a lot of the biology and physiology have some similarities to us.  Our nervous systems and hormonal systems in some ways are very similar.  I think most biologists would say there is absolutely no reason to believe they would not feel pain.  How they perceive it is obviously incredibly difficult to know,  but you pick up a fish and take it out of water and put a hook in its mouth and it struggles.  There is something clearly uncomfortable and not right and that fish perceives stress.”

“When you consider what a fish does in its daily life–it can tell where it is,  identify things and make decisions–it is clear there’s far more going on than anyone suspects,”  Macalister said.  “They learn,  and they have memories, and they can identify people.  They feel  stress and they feel pain. People used to believe fish couldn’t remember anything for longer than three seconds,  but we know now that isn’t true.”

Fish in Hong Kong,  as in most of the world,  have only scant protection under existing anti-cruelty laws,  but Macalister pointed out that laws follow public opinion.

“Attitudes,  as well as the law,  have to change,”  Macalister told Parry.  “It’s an issue of education.”

Industry notice

Some people in the seafood industry are also beginning to notice animal welfare issues. Adam Anson,  who writes for The Fish Site,  The Pig Site,  The Beef Site,  and other online animal industry periodicals,  noted in March 2009 that “Fish welfare needs have been left behind” in developing the aquaculture industry,  even though “In 1997,  the Treaty of Amsterdam agreed that throughout the European Union the concept of welfare is the same in fish as it is in mammals and birds and necessary protection should be applied.”

This concept was reinforced in an April 8,  2009 communication to the European Commission by the EC Fisheries Directorate.

Aquaculture

” This communication recognizes the importance of the welfare of farmed fish for the development of sustainable aquaculture,” summarized Eurogroup for Animal Welfare. “Eurogroup is pleased to see that the Commission plans to launch a project to evaluate fish welfare in aquaculture with a view to possibly introducing legislation on this topic,” Eurogroup added.

Assessed Anson,  “Research into this area has not just been hampered by a lack of investment, but also by the complexity of the issue and the difficulty in achieving scientific, relevant measurements.  A further complexity is added by the numerous different species of fish that are now used in farming.  Research must identify all the varying degrees of behavioral patterns and social activities. Welfare standards must,  in turn,  take these natural drives into account,  applying unique welfare standards for each different species.”

Natural conditions impossible to recreate

Noted Anson,  “Some natural conditions will be impossible to recreate in a fish pen. For instance,  Atlantic salmon will never be able to make their monumental migrations,  risking life to reproduce,  whilst trapped inside the confines of a net.

“It is easy to see how fish welfare is a complex and potentially very expensive issue for the industry,”  Anson concluded,  “but the more that is understood,  the more necessary the research seems.”

(May 2009)

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