Life for apex predators is maybe a little less bad…until you get old, your health declines and you can no longer successfully hunt. And then you starve to death. Never mind that along the way you contend with all manner of parasites and pests and crummy environmental conditions, and you are forced to put up with them because you don’t have access to insecticides, screen mesh, or HVAC.
You know that relief you feel when a few mosquitoes are harassing you at dusk, and you are finally able to come inside and close the door to escape them? What if there was no inside, and what if those few mosquitoes were shitloads and shitloads of biting flies?
Sometimes you don’t even need to wait until you’re old - you just need some calamity along the way. Saw a video last year of a lion that had been kicked in the face by a zebra she had been trying to bring down; her jaw had been shattered/torn and was hanging half off of her face. She couldn’t even drink water anymore, and was probably going to take a miserable day or two to die of dehydration (assuming she didn’t get shredded by opportunistic hyenas).
I’d take that with a large grain of salt. Octopuses, squids, and cuttlefish are all invertebrates but with highly developed nervous systems and ability to interact with each other and the world around them - I would be surprised if they couldn’t feel pain.
A number of years ago I realized that insects all live inside a horror movie.
In addition to starvation, injury, and being eaten by someone else, they also have to contend with horrors like having another creature inject them with eggs and having the larva eat them from the inside out, fungus that takes over their mind and leads them to situations where they are likely to be eaten alive, or just grow mushrooms out of their bodies, and so on. Basically, every movie horror trope you’ve ever seen or heard of is reality to some insect or other.
On a related note, I recently learned that there are some arthropods that can lose their tails and survive, but it leaves them unable to ever shit again, the waste just piles up at the end of the line. But they keep eating and eating and it just piles up at the end of the line until it kills them.
The claim that invertebrates “lack any kind of faculties necessary to process pain” is of course complete crap. Scientists may have said it, but scientists also said certain humans lack intellectual capacity when such claims suited their prejudices.
A study was done with crustaceans which indicated they experience a “key criteria” for pain and are not merely responding to stimuli. (Cite). Given that we already observe they behave as if in pain, and now we have this study, does parsimony require that we assume they do feel pain, or that we invent a separate process and assign it to them so that we can claim they don’t?
A new organ was recently identified in humans.
(Cite). So claims that they “lack a structure” depend on the idea that we have perfectly understood everything.
Scientists studied mice in laboratories for decades without realizing they sing. (Cite). So much for the assumption we know everything about invertebrates, who are vastly more varied than one species of mouse and substantially less well studied.
People feel enormous guilt over their treatment of animals. I know this because I’ve talked to them about it. They get angry preemptively, they lie vigorously, they change the subject, they get defensive. This isn’t controversial – we all know what I’m talking about. People have a stake in animals not feeling pain.
So please regard claims that any particular animal “cannot” feel pain (or any other experience for that matter) as suspect, just as you would when a used car salesman assures you this creampuff was only driven on Sundays, or your teenager swears he will be home by 9:00pm, or a politician promises he has your interests at heart.
Meanwhile, humans with hydrocephaly have demonstrated remarkable cognitive function despite having the “necessary structure” (a brain) largely destroyed by the condition. (Cite). This casts doubt on those who assert someone “lacks a structure” to sense or behave in a particular way – especially when observation shows the animal does appear to act in such a way.
I’ll admit I was wrong to assume invertebrates cannot feel pain; however, a cursory read about pain in invertebrates suggests to me that the jury is out.
Your cite describes researchers letting shore crabs decide between two shelters, and they would shock the crab for entering one. Over ten trials, the crabs preferred the non-rigged shelter. They tried switching the appearance of the shelters which had the same result. They also tried flipping the crab’s starting orientation, and surprisingly the crabs went to the opposite shelter, implying they associated by direction of movement rather than by visual cues. This all indicates learning (in response to pain), as opposed to a reflex.
The same team (Elwood is apparently a leading figure in the field of decapod crustacean pain) did another study three years later but this time they put an opaque partition between the two shelters after the crab picked one, so the crab could not visit both within one trial. Instead of avoiding the shelter associated with electric stimuli the crabs failed to discriminate (as predicted) against the shock-rigged shelter and simply stepped out once the stimuli began (Magee & Elwood, 2016).
There was an earlier attempt to give shore crabs morphine and see if it acts as an analgesic. The hypothesis was that crabs under the effect of an analgesic would not experience pain when they are shocked, and thus be more likely to enter the shock shelter than crabs without morphine. It turned out that morphine reduced the chances of the crabs moving to a shelter at all (Barr & Elwood, 2011).
Elwood attempted to make an argument in support of decapods experiencing pain in 2015, at the end of a paper showing that C. maenas had measurably increased stress markers when shocked. He concludes,
“Although these physiological responses are expected should an animal experience pain, they do not prove the feeling of pain in decapods because absolute proof is not possible for any animal. Nevertheless, coupled with the behavioural responses to a variety of aversive stimuli, they provide evidence of both short- and long-term changes similar to those changes found in cephalopods and vertebrates. That is, the criteria suggested to indicate pain in animals are fulfilled for decapods.” (citations omitted; Elwood & Adams, 2015)
Apparently this prompted thirteen scientists - one animal psychologist, one brain researcher, and the rest who specialize in fish/fisheries/marine sciences - to publish a criticism of Elwood’s collective work, advocating a different set of criteria for pain used in research on fish pain: “activtion of nociceptive pathways, followed by conscious higher level neural processing” (Stevens et al, 2016). They also presented some methodological criticisms. Some of these scientists are known for going against the grain, eg: Rose and Key think fish cannot experience pain because they don’t lack a neurocortex.
Elwood defended his research by saying he never claimed that decapods definitively experienced pain. He points to research demonstrating the existence of nociceptors in other invertebrates, and suggest that an experiment provides support for the same in decapods. That experiment involved local application of benzocaine to glass prawn antennae, which were then stimulated to no effect (where the control group started rubbing their antennae), while swimming patterns remained normal (Barr et. al, 2008). He also says it is impossible to meet criteria of “conscious higher level neural processing” (crustaceans do not have brains in the vertebrate sense, but ganglia). Finally he defends his methodological shortcomings as being a product of the crab’s anatomy - for example, he could not measure heart rate without drilling a hole in the shell and distorting results.
After reading the 2016 shelter experiment, I think Elwood is failing on his own criteria, at least for shore crabs. The only criteria actually met is the presence of stress markers and the avoidance of stimulus, but it has not been shown that shore crabs themselves actually learn in response to supposedly painful stimulus, as opposed to a mere reflex, nor that an analgesic prevents the response, which would be evidence that it is pain rather than reflex. Some of these factors are there in other crustaceans, though; but I am unconvinced. Perhaps most importantly, I could find very little - nothing actually - about the neurobiological mechanism. Does something report back to the central nervous system? I think that question is important here. Does the central nervous system then affect the response? Those stress markers provide some evidence, but without a mechanism it is unclear whether that is a case of causation or correlation.
Sneddon is apparently another leading figure in the field of animal pain, especially fish. Sneddon, Elwood, and others developed the definition and criteria of pain cited in the other papers (Sneddon et al, 2014). She also provides a nice overview of the field titled “Pain in aquatic animals”, although that was written before the 2016 shore crab experiment (Sneddon, 2015).
All in all, the indications are that it is quite possible that crustaceans feel pain. But I am not convinced either way.
~Max
Barr, S., & Elwood, R. W. (2011). No evidence of morphine analgesia to noxious shock in the shore crab, Carcinus maenas. Behavioural Processes, 86(3), 340-344. doi: 10.1016/j.beproc.2011.02.002
Barr, S., Laming, P. R., Dick, J. T. A., & Elwood, R. W. (2008). Nociception or pain in a decapod crustacean? Animal Behavior, 75(3), 745-751. doi: 10.1016/j.anbehav.2007.07.004
Elwood, R. W., & Adams, L. (2015). Electric shock causes physiological stress responses in shore crabs, consistent with prediction of pain. Biology Letters, 11(11), 20150800. doi: 10.1098/rsbl.2015.0800
Magee, B., & Elwood, R. W. (2016). No discrimination shock avoidance with sequential presentation of stimuli but shore crabs still reduce shock exposure. Biology Open, 5, 883-888. doi: 10.1242/bio.019216
Sneddon, L. U. (2015). Pain in aquatic animals. Journal of Experimental Biology, 218(7), 967-976. doi: 10.1242/jeb.088823
Sneddon, L. U., Elwood, R. W., Adamo, S. A., & Leach, M. C. (2014). Defining and assessing animal pain. Animal Behavior, 97, 201-212. doi: 10.1016/j.anbehav.2014.09.007
Stevens, E.D., Arlinghaus, R., Browman, H. I., Cooke, S. J., Cowx, I. G., Diggles, B. K., … Wynne, C. D. L. (2016). Stress is not pain. Comment on Elwood and Adams (2015) ‘Electric shock causes physiological stress responses in shore crabs, consistent with prediction of pain’. Biology Letters, 12(4), 20151006. doi: 10.1098/rsbl.2015.1006
I think it just means wild critters (to the extent they can be anthropomorphized) are life-hardened and realistic, and they tend not to bitch about their misfortunes in the way a soccer mom does when there’s not quite enough caramel in her Frappuccino.
But how can we know that? How do we know that animals don’t suffer emotional distress? How do we know they don’t mourn their dead, miss the disappeared from the herd or flock?
We don’t know either way and to assume we do is hubris.
Seems to me that we do know that animals can and do feel end exhibit such loss. Elephants come immediately to mind. Others like whales, dogs, gorillas, etc…
If you’re the snail, well damn, sucks to be you. This parasite will take over your brain and body. It will compel you to climb out into broad daylight, and it will pulsate and thrust within your swollen eyestalks to make you look like a tasty maggot for any nearby birds. One of those birds will eat you, propagating the parasite’s eggs in its droppings. Then your friends and family will eat those droppings, consigning themselves to the same fate as you.
Machine Elf, you ninja’d me, I was going to mention the horror of the zombie snail! Freaked me right the hell out.
But… I don’t think most animals feel the same sort of misery that we modern humans would if we lived outside 24/7 with no modern conveniences. I’m sure you could make them feel distress if you set yourself to it, but the normalities of outdoor life is just that, it’s normal.