# Do inverts feel pain??



## Slinkies mum (Jul 15, 2008)

This came up on another thread and I wondered what every body else thought. I know the general understanding is that they don't but I have my doubts about that.


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## GRB (Jan 24, 2008)

The supposed consensus is no.

There's a few points of evidence:

1) If you damage a limb via crushing the force applied on each step with the damaged leg is the same as that of an undamaged leg. Basically, they don't limp or favour damaged limbs.

This is also linked to the notion that most inverts can alter leg forces for specific tasks when they need to, yet seem to lack the ability to alter it on damaged limbs, which you would expect if they "hurt". 

2) Most invertebrates have a sparse net of neurons, and large areas are not innervated by any nerve cells.

This, however, is utter rubbish when it comes to spiders. Trichobothria (those long hairs on their legs) on spiders are innervated by 3 nerves each and in tarantulas the majority of urticating hairs are also innervated by a nerve ending each. Even scale hairs (the tiny ones that make up colouration in many species) seem to have some neuronal attachment. (see Foelix 1996)

So, based on that just about the entire body is covered in structures that are linked to neuronal structures, I dispute that point in spiders...

3) There's something to do with their cognitive abilities that suggests they can't process pain but I can't remember it, nor do I agree with it. 

I think they do feel some sort of pain however, because the way they struggle when you catch a leg etc seems more frantic than just trying to escape. And if they can feel 'fear'(I've read this cited in some papers referring to insect panic reactions when they fall into pitcher plants) then I would expect they are capable of experiencing other sensations.


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## selina20 (May 28, 2008)

I agree with GRB on this one. However i have noticed that spiders will "flinch" if u catch one of their legs in the tank door etc. Surely this is some kind of pain reflex?


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## ilovecornsnakes (Apr 4, 2008)

i'd have thought every live animal can feel pain so they can learn what hurts and is therefore damaging and know not to do it again (course i have no knowledge of spider / invert body workings and i'm studying chemistry not biology)


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## LiamRatSnake (Jul 3, 2007)

They thought for a long time that fish don't feel pain, this was later proved unture. It will probably depend on the species to be honest.


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## Lucifus (Aug 30, 2007)

Dubious. There is evidence on both sides but major studies into the field tend to show that current evidence means its unlikely. However its possible that we cant detect their pain as they may feel it differently.


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## miss_rawr (Mar 18, 2009)

i reckon they can


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## kernix (Apr 2, 2009)

i thought every living thing could


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## AshMashMash (Oct 28, 2007)

GRB said:


> 3) There's something to do with their cognitive abilities that suggests they can't process pain but I can't remember it, nor do I agree with it.


Very interesting post GRB. 

Have you seen this? (I know, not an arachnid, but an invert non-the-less):

Hermit crabs can remember pain | Practical Fishkeeping magazine



> Not only were the crabs found to react adversely to the electric shocks, but the study – published in the journal Animal Behaviour – also suggests that the crabs would actively avoid receiving future shocks.


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## joeyboy (Jul 19, 2008)

I'd always assumed they felt pain but didn't have the emotional capacity to process it like we do.

So if you stabbed a human it would hurt because you also feel fear, distress, sadness, emotional pain etc etc

With inverts I'd imagine it's more a robotic kind of response so if you stabbed a T's leg it would flinch as an automatic nerve response and move away but it's "brain" would just be a like a computer: " pain received in 1 first left leg, move away from source of pain, possible detachment of limb required, detaching. Wounded limb detached, bleeding stopped." :lol2:

So what I mean is they "feel" the pain but don't think about it, it's more an automatic thing.


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## ph0bia (Feb 21, 2009)

kernix said:


> i thought every living thing could


Nope, most insects and arthropods cannot.



LiamRatSnake said:


> They thought for a long time that fish don't feel pain, this was later proved unture. It will probably depend on the species to be honest.


It depends on how you look at it. For instance, if you had a fishook in your mouth digging into your cheek, would you swim away? Fishing hooks don't hurt them, but they are sensitive to other pains.



selina20 said:


> I agree with GRB on this one. However i have noticed that spiders will "flinch" if u catch one of their legs in the tank door etc. Surely this is some kind of pain reflex?


Again, it depends on your definition of pain. This flinching (though something I've never eye-witnessed as I've yet to catch one in the door - though I imagine it to be similar to the flinch they make if a locust begins climbing their legs) I would imagine to be more a reflex than pain. But what is pain? Pain, by definition, is the nervous response to an unwelcome stimulus (ie, crushing, piercing etc). Paralyzed people often lose the pain reception in the effected area and so would not realize they had stepped on a nail etc, though it would still bleed. In this sense, a tarantula of course realises when it has its' leg stuck or if it's under attack and has something snacking on it.

But is this pain like we feel? No. A tarantula does not have the capability mentally to experience pain on the levels we do. We can differentiate between "Ouch, that pin-prick hurt" and "OMFG, my arm is broken, the bone is poking through the skin". A tarantula does not posses this capability as this is intrinsically linked to a sense of self. What I mean here is that studies have shown that kids who grow up with a parent who reacts to a cut finger as "Oh dear, let's sort that out" will have a greater tolerance for pain than those whose parents panicked every time little Jimmy grazed his knee.

Tarantulas, whilst biologically incredibly advanced (especially in chemo and kino-sensitivity) are mentally simple. Imagine the earliest computers.

I'd not be surprised if all tarantulas have is "This leg feels fine" - "This leg is in danger". They react to stimuli in very specific, almost binary methods (*item introduced close to defensive spider* "Smells like food, attack." - "Smells like danger, rear or run?")



*TLDR: *Spiders do not feel pain in the same sense we do but are certainly aware if they're in a dangerous position.


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## Slinkies mum (Jul 15, 2008)

As said I would be very doubtful that no species of inverts feel pain. But then you read really mis-leading things like 'don't pour salt on slugs and snails as it is a very cruel and painful way to kill them'.


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## GRB (Jan 24, 2008)

ph0bia said:


> It depends on how you look at it. For instance, if you had a fishook in your mouth digging into your cheek, would you swim away? Fishing hooks don't hurt them, but they are sensitive to other pains.
> 
> Surely thats a rather false analogy: A fish has no arms to remove a fish-hook so it's only response would be to thrash around? How can you interpret swimming in such a manner purely as an escape response rather than a response to pain AND attempt to escape?
> 
> ...


See Above.

References:

Evans T. Kin recognition in a social spider. _
Proc. R. Soc. Lond. B _1999 266, 287-292

D.M Rowell and L. Aviles (1995) . Sociality in a bark-dwelling huntsman spider from Australia, _Delena cancerides, _Walkenaer (Araneae: Spassaridae). Ins.Soc. 287-302.


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## ph0bia (Feb 21, 2009)

In my post I was discussing the definition of pain, and if by that we take it to mean "nervous stimulation of discomfort", then the answer is simple, yes, they feel pain as can be seen if you trap their legs (apparently).

Correct, memory is not required to feel pain, nor was I suggesting that a sense of scaling is necessary to feel pain, but people tend to take pain to mean emotional or physical suffering, which the spiders do not feel.

Though I don't want to draw this topic onto fish, what I was meaning there is that a fish on a hook swims directly AWAY from the line, tightening the hook into it. If the hook was hurting it, it would try different directions and eventually conclude that swimming towards the fisherman slackens the line and stops digging the hook in. Not saying they'd think it like that, more "Ow, this way hurts...", "Ow, so does this...", "Ah, that's better." 

Finally, as for references, I don't entirely recall where it all came from, but there was a fantastic article a few summers past (August/September 07) in New Scientist Magazine about spider behaviors, involving a test where a spider sat on one branch for an hour or two, then climbed down, up the next stick and knew the way (along a mazelike construction of branches). The article later went on to discuss standard arachnid 'thought processes'. As for the Y-Maze, spiders innately follow silk draglines; but whilst binary may be a bit basic, what I meant was that you can imagine them as a computer program.

They have a list of instructions and programmed responses, a spider will never plan ahead, second guessing your next move. They are very much reactionary creatures.


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## selina20 (May 28, 2008)

Surely a flinch even if its a response is a response in accordance with the pain so therefore must mean they can feel pain???? Maybe not in the same way as us but they do have a very complex nervous system?


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## GRB (Jan 24, 2008)

ph0bia said:


> In my post I was discussing the definition of pain, and if by that we take it to mean "nervous stimulation of discomfort", then the answer is simple, yes, they feel pain as can be seen if you trap their legs (apparently).
> 
> Correct, memory is not required to feel pain, nor was I suggesting that a sense of scaling is necessary to feel pain, but people tend to take pain to mean emotional or physical suffering, which the spiders do not feel.
> 
> ...


That concluding comment is far from true. Have you read of the genus _Portia? _

_Portia_ can alter hunting behaviour for specific prey items, adjust to local terrain and have been shown to alter their hunting stratagey if conditions change during the hunt. The interesting facet is that it appears they can forward plan, because stratagies involving orb weaver prey often involve heading in a completely opposite direction to the prey item before doubling back on higher vegetation in order to abseil down and snatch the prey from the web.

Other spiders such as Lycosids also "forward" plan when other competing predatory Lycosids are around by reducing dragline silk which contains pheromones that can identify them to other lycosids.


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## ph0bia (Feb 21, 2009)

GRB said:


> That concluding comment is far from true. Have you read of the genus _Portia? _
> 
> _Portia_ can alter hunting behaviour for specific prey items, adjust to local terrain and have been shown to alter their hunting stratagey if conditions change during the hunt. The interesting facet is that it appears they can forward plan, because stratagies involving orb weaver prey often involve heading in a completely opposite direction to the prey item before doubling back on higher vegetation in order to abseil down and snatch the prey from the web.
> 
> Other spiders such as Lycosids also "forward" plan when other competing predatory Lycosids are around by reducing dragline silk which contains pheromones that can identify them to other lycosids.


I think Portia was the species in question, but forgive me, when I said "spiders" in the above example, I meant tarantulas, which do not forward think like lycosids and other hunting spiders do. Also, I'm not stating the fish "knows" but it would soon discover it.



selina20 said:


> Surely a flinch even if its a response is a response in accordance with the pain so therefore must mean they can feel pain???? Maybe not in the same way as us but they do have a very complex nervous system?


We're doing the usual here, it seems... I've not stated they can't feel pain, as long as by 'pain' you mean the reaction to a dangerous stimulus. All I have stated is that they do not feel pain as we do, it is merely as a "This is not good" response, rather than our "It's not good, but I can cope" and "Okay, this hurts" and "Oh my god Oh my god Oh my god Oh my god...". 

Love the scientific terminology there 

Tarantulas do not have a very complex nervous system. They have incredibly complex sensory organs (their 'hairs' etc...) but not their nervous system as we do.

We can feel variations of heat - Tarantulas can also.
We can feel variations of pressure - I read somewhere that tarantulas cannot.
We can feel variations of piercing (ie, the difference between a hypodermic needle and a knife blade) - tarantulas can but on a much more subtle level.

Essentially, what I'm getting at is that a tarantula can:
"Sense and react to stimuli which are of harmful intent such as a trapped foot or a cricket bite"
However, I would not regard this as 'pain' which I personally believe to be defined as 'physical suffering'. It's a subtle difference, perhaps, but whilst I would feel incredibly sorry for the tarantula and bad with myself if I trapped its' leg in a door, I would not worry about the spider moping in it's burrow writing poetry and listening to My Chemical Romance. The spider senses the 'pain' and then very quickly "gets over it".

Humans don't. We ache or feel sore after.


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## Harbinger (Dec 20, 2008)

Cant be asked to read the previous comments but the way I see it if something can feel you touch it im guessing it can feel you hurt it.


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