Do animals without backbones, such as squids, crabs, and lobsters, feel pain? New research suggests they do.
Evolutionary neurobiologist Robyn Crook and colleagues at the University of Texas Health Science Center have recently shown that cephalopods (a group including squid and octopi) possess nociceptors, nerve cell endings that quickly transmit potentially-damaging stimuli to the central nervous system. Crook “also has found that octopuses show much of the pain-related behavior seen in vertebrates, such as grooming and protecting an injured body part,” as New Scientist reported. The animals are also more likely to retreat and squirt ink when touched near a wound than elsewhere on their body.
Here’s what’s going on with squid:
This research compliments work done by Robert Elwood, a professor of animal behavior at Queen’s University in Belfast, Northern Ireland, showing that crabs and lobsters probably feel pain:
The jury is still out on smaller invertebrates like insects. It’s reasonable to think that if small crustaceans can feel pain, then so can some insects, which can have similar-sized nervous systems. But one researcher in this area, Hans Smid at Wageningen University in the Netherlands, said insects do not show pain-related behavior and he is convinced they do not feel pain.