Do tarantulas have brains?

Alicemolted · Nov 6, 2007

and if they do.. are they called something else? and if they dont.. how on earth do they function?
x

butch4skin · Nov 6, 2007

They have "coalesced ganglii" or something. Basically a crappy excuse for a brain, though I'd never say that in front of any of mine.

Stylopidae · Nov 6, 2007

There is a lot of information about how the nervous systems of invertebrates is set up here.

http://homepage.ntlworld.com/spydawebb/anatomy.html

They do have a brain and a nervous system with a higher degree of centralization than most invertebrates, but their nervous system most likely works in a similar fashion.

Their nervous systems are nowhere near as complex as ours are...they don't sleep, they don't feel pain, don't feel blue, etc.

They recieve information and react to it. There is very little information processing capability in their nervous system.

http://www.earthlife.net/chelicerata/s-anatomy.html

Merfolk · Nov 6, 2007

You can't claim for a total absence of intelligence, but it's limited.

They can recall spacial disposition of things and such...

Vietnamese510 · Nov 6, 2007

wow

i never knew that Ts dont sleep

Stylopidae · Nov 6, 2007

Merfolk said:
You can't claim for a total absence of intelligence, but it's limited.

They can recall spacial disposition of things and such...

They can also learn behaviors...one person reported his tarantulas learned to tap their waterdishes on the side of their enclosures.

Their cognative abilities are very limited. I don't like to use the word intelligence because the second I use that word, people start comparing them to cats, dogs and higher animals with much, much more complex nervous systems and start attributing abilities to tarantulas that are impossible for the tarantula to posess given the layout of it's nervous system.

Of course...when you ask a question like this, you're really asking two questions (whether or not you like/realize it).

First question...how is the term brain/intelligence defined?

Second question...does the animal/organ/behavior meet this definition?

The answer to the second question is dependant on the first and by manipulating the answer to the first question, you can come up with any answer to the second question you'd like.

The relevant definition of intelligence from Dictionary.com:

capacity for learning, reasoning, understanding, and similar forms of mental activity; aptitude in grasping truths, relationships, facts, meanings, etc.

Well, under this definition tarantulas and similar inverts posess no intelligence because this definition was formulated to compare and contrast the cognative abilities of different people and higher animals.

A tarantula can not understand, reason, grasp truths, understand most types of relationships (again...another definition I could fiddle with), facts nor meanings.

However, they can certianly learn to a certian degree.

So I prefer to stay away from loose terms like 'intelligence' and instead explain the nervous system and it's capabilities in a very long, drawn out explanation because short explanations often leave people with the wrong impressions.

UrbanJungles · Nov 6, 2007

Touch alone can determine whether or not something is a danger usually by smell. For example, if a T touches (smells) something unfamiliar it may be very cautious until it can determine the new thing is not a threat. If the "thing" keeps coming after them then there's no doubt it's a threat and a fight or flight response is initiated.

Code Monkey · Nov 6, 2007

butch4skin said:
Or better yet, how do we know that an animal can interpret stimuli through touch as dangerous, yet most likely cannot feel physical pain.

Easy, pain is a psychological phenomenon linked to unsafe stimuli. No nervous system complex enough to have such psychological phenomena means no pain. For example, you can reduce a cockroach (similar number of neurons, analogous physiology and anatomy) to basically the nerve trunk in a isotonic solution and it still responds as if the cockroach were whole, alive and "enjoying" a nice bit of PB&J dropped under the cabinet.

Stylopidae · Nov 6, 2007

butch4skin said:
Or better yet, how do we know that an animal can interpret stimuli through touch as dangerous, yet most likely cannot feel physical pain.

butch4skin said:
I've always wondered, what's the difference between being able to interpret stimuli by touch as dangerous(which Theraphosids are obviously capable of) and being able to feel pain?

That is all explained here in quite a bit of detail.

You need to know the physical processes that go on when you feel pain, as well as how and where that information is processed.

Then, compare and contrast.

If an animal lacks the opsins that respond to any sort of color, we can safely assume that animal is colorblind. Whether or not an animal feels pain works on similar logic.

One of my posts from that thread on the subject:

Cheshire said:
Again...this is based upon what?

400 year old research?

We didn't even know about bacteria in 1493, so anything done by Paracelsus is completely irrelevant in this conversation.

It's safe to say that every week that passes, we learn more about the human brain than we the entirety of what we knew in 1493.

If we were arguing about poriferans or cnidarians, this would be a much shorter post.

There have been tremendous advances in neuroscience since then. MRIs and PET scans that allow us to see exactly what is going on in the brain and by sticking pins and needles in the feet of poorly paid college students and even lesser paid terminally ill patients (and just plain old injury victims who are having a bad day and on top of it...aren't paid for their suffering), we can see what sections of the brain burst alive in reaction to any sort of stimulus.

By dissecting the encephalon of corpses, we can see how our brain is laid out, how the nerves are connected and exactly how those sections are set up.

The same goes for invertebrates to a certian extent. I've never put a tarantula through an MRI machine, but I can compare their loose clusters of ganglion to the tightly wound definitely seperate sections of the human brains and other vertebrate brains.

Hell...we know that the brain is the pretty much the epicenter of all activity in the body instead of the heart.

Back then in an age where the scientiffic method was just beginning to see the light of day, we knew nothing of the brain.

I'm not debating whether or not dogs can feel pain. Dogs are vertebrates and have complex brains.

I'm asking 4 questions.

1.) How is pain defined?

I am defining pain as the sensation you and I feel. As in...ouch, that hurts. The feeling you get when you burn your hand on a stove. Some sort of localized physical suffering associated with an injury or disease, or by physical discomfort.

This seems to imply a degree of complexity that I will tackle later.

2.) How is pain felt?

What I am doing in my posts is pointing out exactly how complex a feeling pain is. There are no less than 4 sections of the brain involved in processing this sensation in mamallian brains.

3.) What similar structures are in the invertebrate brain that would allow the creature to process this particular stimuli in a way similar to the definition of pain I listed above?

The vertebrate brain lacks every single one of the sections that are responsible for feeling pain in mammals, birds and any other higher life form. Therefore I can hypothesize that the sensation invertebrates feel as pain is very different than the sensation that you and I feel as pain.

Thus, vertebrates and humans would react differently when injured similarly.

4.) Are there any real life observations to support this hypothesis?

When a dog breaks or otherwise injures it's leg, the dog lifts it's leg off the ground and does not apply weight on it.

When you damage the tarsi of a roach, the roach acts as if the injury never happens.

A human will only amputate a limb if their life is in mortal danger (See Aron Ralston).

A tarantula will amputate a limb for reasons far less...if the limb is broken or otherwise doesn't work quite right.

Imagine cutting off your own broken leg out of boredom.

A willingness to amputate limbs by itself at will more than suggests that an overwhelming negative sensation is not felt by the animal combined with the effect that the animal doesn't favour the new stump.

The reaction of this mantis (which I have also observed in my own captive breeding of similar species) also supports my theory.

As JR47 pointed out earlier, there are extreme instances where vertebrates won't feel pain when faced with a massive injury due to traumatic shock, but the fact that a bug will live like this for days wheras a human will either die from this injury or feel pain (in other words, have visible symptoms such as the inability to move, favoring that area of the body (clutching stomach in an attempt to gate the pain) and not going about the normal routine for days on end) hours later (after first aid has been administered) negates this point.

So based on the reasons I've outlined above, there is no reason an invertebrate should feel pain as it is classically defined for us humans.

All of this information when taken into context pretty much proves that the sensation you and I feel and the sensation that you are anthromorphizing your animal to feel are quite different. Invertebrates simply do not have the capacity to feel any sort of localized physical suffering.

If you can find some decent proof otherwise (post anything by PETA and I will reach through the computer screen and slap you) from any sort of peer reviewed neuroscience journal or any site belonging to an instute of higher education, I'll gladly read through it.

Until then, I guess I'll have to keep spoonfeeding.

If you're actually interested in where I'm getting the information on exactly how the vertebrate and invertebrate brain works, I will happily refer you to two of my previous posts on the subject.

http://www.arachnoboards.com/ab/showpost.php?p=846373&postcount=45
http://www.arachnoboards.com/ab/showpost.php?p=845968&postcount=34

Travis K · Nov 6, 2007

to all the vegitarians

If it taste good eat it! Who cares what it feels. Personally i would love to go to asia and eat one of the many T's they have at some of the venders on the street, nad ship a live one off to the states. LOL, i have an uncle in Thai Land, i should ask him to ship me some T-kabobs, and maybe some live T's when the weather gets better.

Yeah i always thought it was funny when people say some things can feal pain and others not.

Stylopidae · Nov 6, 2007

Travis K said:
If it taste good eat it! Who cares what it feels. Personally i would love to go to asia and eat one of the many T's they have at some of the venders on the street, nad ship a live one off to the states. LOL, i have an uncle in Thai Land, i should ask him to ship me some T-kabobs, and maybe some live T's when the weather gets better.

Yeah i always thought it was funny when people say some things can feal pain and others not.

Nobody's come in preaching yet...hopefully it stays that way.

Don't encourage, don't provoke.

problemchildx · Nov 6, 2007

I like this thread, learned a lot already from you guys!

Stylopidae · Nov 6, 2007

Thanks for the compliment...and for overlooking a huge typo in a vital part of that post

butch4skin · Nov 6, 2007

I knew you meant invertebrates

Calucifer · Nov 6, 2007

Oh my god that thing...
about cockroaches, nerve trunks and isotonic solutions....
That just gave me the creeps

lucanidae · Nov 6, 2007

Ugh.....here we go on this no pain due to primitive nerve system stuff again. This time I'll just throw out my references first and let you decide for yourself, the author of this paper is Tom Eisner....father of chemical ecology. He's a very nice old professor I am currently taking a class from here. If you aren't familiar with his work....just do a quick google search.

Here's the paper I want all those who think no invertebrates feel pain to read:

Spider leg autotomy induced by prey venom injection: An adaptive
response to "pain"?

http://www.pnas.org/cgi/reprint/80/11/3382

It should be free for you to download from that page, please let me know if it isn't.

Here's a start:

Field observations showed orb-weaving spiders (Argiope spp.) to undergo leg autotomy if they are stung in a leg by venomous insect prey (Phymata fasciata). The response occurs within seconds, before the venom can take lethal action by spread to the body of the spiders. Autotomy is induced also by honeybee venom and wasp venom, as well as by several venom components (serotonin, histamine, phospholipase A2, melittin) known to be responsible for the pain characteristically elicited by venom injection in humans. The sensing mechanism by which spiders detect injected harmful chemicals such as venoms therefore may be fundamentally similar to the one in humans that is coupled with the perception of pain.

The paper is a very good read, and the author is one of the geniuses of entomology of our time. The discussion is probably the most important part to read.

lucanidae · Nov 6, 2007

Here then, try this on for size;

Another article all the no pain camp should read:
SENTIENCE AND PAIN IN INVERTEBRATES
http://66.102.1.104/scholar?hl=en&lr=&safe=off&q=cache:LU9NJSpLA6MJ:vkm.no/dav/0327284150.pdf+

Some food for thought from it: (This should also answer the original posters question. The number of threads that don't consider the literature and simply jumped to well established arachnoboards conclusions is very large....this reminds me of the 'spiders don't have pigments' rumor here)

The central nervous system of spiders has some resemblance to those of crustaceans and insects, but is even more concentrated (Brusca & Brusca 2002). The brain includes a protocerebrum and tritocerebrum connected to ventral nerves, while all the ganglia are more or less fused
with the brain. In scorpions the ventral nerve cord has seven ganglia.

As pointed out by Sherwin (2001), we may be mistaken in assuming that invertebrates have a reduced capacity to experience suffering. Suffering is a private experience, or a negative mental state that cannot be measured directly. The responses of invertebrates to noxious conditions are often strikingly similar to those of vertebrates. Several experimental studies have shown that invertebrates such as cockroaches, flies and slugs have short and long-term memory, have ability of spatial and social learning, perform appropriately on preference tests, and may exhibit behavioural and physiological responses indicative of pain. The similarity of these responses to those of vertebrates may indicate a level of consciousness or suffering that is normally not attributed to invertebrates

Opioid substances are also known from invertebrates. If their function is similar to that in vertebrates, this is an indication that invertebrates may feel pain, which is reduced by the opioids. At present no certain conclusion can be drawn, but opioids are interesting in considering the question of pain in invertebrates. Examples of the presence of opioids are known from different groups of invertebrates

Code Monkey · Nov 6, 2007

lucanidae said:
The paper is a very good read, and the author is one of the geniuses of entomology of our time. The discussion is probably the most important part to read.

The bolded part of your quote does not mean what you imply. It simply refers to a sensory feedback system where they are "aware" of the venom's presence prior to significant damage to the area of the sting. It would be more surprising if venoms that evolved prior to a bunch of spined wonders poking into bee hives for a sweet snack didn't elicit sophisticated responses in inverts. After all, they've had a lot longer to engage in their physiological selection warfare than those of us who go "OW!" or, even, "HOWL!".

Sensing and responding to damage, even if in a relatively sophisticated manner, does not imply a pyschological ability to suffer. Otherwise, this is all semantic masturbation where people try to define pain as something other than that (its most common and, for that matter, legal definition). If the ability to "feel pain" is defined as anything other than psychological suffering then, sure, go nuts with the inverts feel pain. So don't bacteria for that matter, which also show preferences and aversions in analogous tests, and they don't even have a nervous system.

But, if you accept the logical premise that awareness, sentience, and full blown self consciousness are an emergent phenomena based in the complexity of the animal's brain, then you've got to be crazy to assume that it's even possible that animals who have fewer neurons in their entire body by an order of several magnitudes than your average vertebrate has in their foot (or equivalent) is anything other than on the cusp of awareness and certainly nowhere near sentience and, therefore, the capability of suffering.

lucanidae · Nov 6, 2007

Is it this bold quote?

As pointed out by Sherwin (2001), we may be mistaken in assuming that invertebrates have a reduced capacity to experience suffering. Suffering is a private experience, or a negative mental state that cannot be measured directly. The responses of invertebrates to noxious conditions are often strikingly similar to those of vertebrates. Several experimental studies have shown that invertebrates such as cockroaches, flies and slugs have short and long-term memory, have ability of spatial and social learning, perform appropriately on preference tests, and may exhibit behavioural and physiological responses indicative of pain. The similarity of these responses to those of vertebrates may indicate a level of consciousness or suffering that is normally not attributed to invertebrates.

or the spider bold quote?

The spider bold quote wasn't supposed to be 'proof' of anything, just a stimulus to get people to read the paper and think for themselves about it. There seems to be this dominance of one side of the argument on these boards that comes from what seems to be years of no one fact checking on the side that maybe, possibly, and even enough of a question to test for years and years and years over....that these things might feel something like pain.

I didn't intend for these select quotes to be the end all of this argument on these boards, I of course expected literature counter references (which exist...I found them) and strong defense from many of the people who have called others incompetent on this subject thread after thread.

Nivek · Nov 6, 2007

I know one thing. If they can feel pain, they are nature's biggest bad a**es. Periodically popping out of their own skin and dropping appendages like a bad habit, lol. I don't have any relative information to add to the discussion, but I do have a question to throw out. Does anyone know which invertebrate has the most complex nervous system and such? I always assumed it would be a centipede for some reason.

Do tarantulas have brains?

Arachnopeon

Arachnoprince

Arachnoking

Arachnoprince

Arachnoknight

Arachnoking

Arachnoprince

Arachnoemperor

Arachnoking

TravIsGinger

Arachnoking

Arachnoprince

Arachnoking

Arachnoprince

Arachnosquire

Arachnoprince

Arachnoprince

Arachnoemperor

Arachnoprince

Arachnoknight