If an animal feels no pain and doesn't possess higher cognitive abilities, should it have protection under animal cruelty laws? For invertebrates like lobsters and crabs, which are best cooked alive, the answer to that question is currently no -- one reason why researchers in a new study attempted to prove the animals experienced pain, the Washington Post reported.
"Early on in my career I realized that when the law speaks of animals, it does not mean invertebrates," Antoine Goetschel, an international animal law and ethics consultant based in Zurich, told the Post. "As long as the common opinion is that invertebrates do not suffer, they are out of the game."
Complicating the issue is the relationship between pain and reflex. An animal in adverse conditions to its health might automatically respond to the threat in order to preserve its safety -- and not necessarily to avoid pain.
In order to test for pain, scientists had to isolate it from the reflex. They did so by spraying acetic acid on the antennae of prawns, a large swimming crustacean (and I believe the derogatory name given to aliens in "District 9"). The creatures groomed the area in response, but didn't when a local anesthetic was applied -- indicating that the behavior wasn't to tend the wound, but more likely to alleviate pain. In another test with crabs, they demonstrated the same desire to soothe areas of induced pain.
"These are not just reflexes," said Robert Elwood, the study's lead author. "This is prolonged and complicated behavior, which clearly involves the central nervous system."
Elwood and colleagues also tested crabs' ability to learn from pain by shocking them whenever they went into one of two pre-arranged shelters, which they gradually understood to avoid.
Since around 98 percent of all animal species are invertebrates, researchers wonder if all feel pain to some degree. If they do, it could complicate research involving insects.
For now, the answer to the insect question appears much more certain than it had been for spineless sea creatures.
"I am absolutely convinced that insects do not feel pain," said Hans Smid, who studies the brain and behavior of wasps at Wageningen University in the Netherlands.
