Advertisement So this thread was brought about as I was in my car thinking about all the replies I have gotten from my first post that there was alot of disagreement on. That thread went into several directions from my main question so I'm expecting this one to do the same and am posting in chat. However, it says in the description of chat that it is fun and casual, Is personal inconclusive research fun? Casual? Debatable. Haha. I don't mind if it is moved by admin. I will lay out my thought pattern and the things I found online from sources such as books to scholarly articles of research and even the Encyclopedia Britannica online. This will be lengthy and I encourage people not to just hit the disagree button because I won't know which section you specifically disagree with or why. I cannot claim these sources are correct, because I am a skeptic not cynical, I am just gathering them and hoping correction to what I find will be made or clarified. So let's start from the beginning, I will put my thoughts about each thing I find and what lead me to other areas. And I hope I make it clear enough to follow. Some of these topics I have set aside for now to come to my ultimate question of the night which regards the title. So I was driving home and thought about stress to a Tarantula and if it was part of the nervous system or a higher response of emotion that most claim isn't possible, I refreshed my knowledge from the information on these forums on all the listed behaviors of a stressed tarantula and decided to start with looking where stress is derived in humans because Google loves giving information as it pertains to humans first. And in my finding from Harvard health, it says this about where the stress response comes from and what it activates, "After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands. These glands respond by pumping the hormone epinephrine (also known as adrenaline) into the bloodstream." Here's the link: https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response Okay Harvard, so it is the nervous system and tarantulas have one so they may have stress in a way humans relate to. Probably isn't some higher emotional thing but just nerve response. Okay so that leads me to think about the structures of anatomy for a tarantula, like they may truly have stress but how does their body process it? In my last thread it was quite a mass of opinions where one commenter said the tarantula does not have a brain but they have a ganglion and people agreed with them. Now I have looked on these forums and there's even posts from back in 2007 where commenters said a ganglion is a type of simplified brain in regards to if tarantulas have them. (Btw that topic lead to pain recognition and intelligence eventually, not staying on what a brain is) So in my first thread I was told I was really, let's say, ignorant. Which I never claimed to know any more than anyone, but I am willing to do the research for even the smallest things. Hense why we are here. So I decided to look up if spiders don't have brains then how their body process stress, like if they even have a hypothalamus or an adrenal gland or another structure that processes stress. I didnt find much, but I know the information may be out there but buried under Google ads and unrelated links. So I decided to instead look up if they had epinephrine, which if you remember Harvard said humans do, which would support more of a theory they have some kind of structure in their organs for stress response. And I came across this scholarly research article: MONOAMINES IN THE BRAIN OF TARANTULAS (APHONOPELMA HENTZI) (ARANEAE, THERAPHOSIDAE): DIFFERENCES ASSOCIATED WITH MALE AGONISTIC INTERACTIONS It was in PDF format so I don't have a link for it but you guys can Google it, it is interesting. This is the first part of the abstract: "Experiments were conducted to determine the effects of male-male agonistic encounters on changes in monoamine neurotransmitter concentrations in the supraesophageal ganglion (brain) of the tarantula, Aphonopelma hentzi." I read the entire study because it was interesting and one thing they did measure in their experiment was change in epinephrine. So it did conclude they for one have it. So okay that is cool, getting somewhere, but whoa, wait. Did they just say the ganglion was a brain? This is where that little skeptical part of me starts to fire. So obviously I got too distracted by that to continue to look into what exactly controls the stress response. Don't worry I will get back to that later in time because now I feel something isn't justified. And yeah all of this is a lead-on to the main topic (as title suggests) for people reading who are wanting me to get to the point, haha sorry, it's coming I swear! So now I look into is the ganglion technically a type of brain. To clarify I don't mean by measures of intelligence or anything the 2007 thread on these forums mentioned. I mean just as a tarantula has a leg, it may look very different from other legs and technically function differently, but it is still considered a leg. So I get to googling. And I find this from the Encyclopedia Britannica: "The nervous system of spiders, unlike that of other arachnids, is completely concentrated in the cephalothorax. The masses of nervous tissue (ganglia) are fused with a ganglion found under the esophagus and below and behind the brain. The shape of the brain, or epipharyngeal ganglion, somewhat reflects the habits of the spider;" here's the link: https://www.britannica.com/animal/spider-arachnid/Nervous-system-and-senses Okay so even the Encyclopedia Britannica suggests it is a type of brain, but feel that? It's my skeptical mind saying "but what if we can't trust the Encyclopedia Britannica?" Sigh okay we will look more, but first I'm going to finish reading this because it is also pretty interesting. And if you guys want to look through it, it has way more information like functions like nerve stimulation and even digestion. So as I look for more information about the ganglion I find this book: The Tarantula Keeper's Guide: Comprehensive Information on Care, Housing... By Stanley A. Schultz, Marguerite J. Schultz Here's a link to the preview of the book from Google: https://books.google.com/books?id=rIVAkA3IlHgC&pg=PA45&lpg=PA45&dq=tarantula+hypothalamus&source=bl&ots=YaszFeXUym&sig=3Y4_DknYQmnhl7F8aFap56DMJyU&hl=en&sa=X&ved=2ahUKEwisy-mKpP_dAhUQ0lMKHUCwBJEQ6AEwAHoECAAQAQ#v=onepage&q=tarantula hypothalamus&f=false So for the first thing I saw about this book was the part on the nervous system and hey it mentioned our hypothalamus! Sweet! It says they have a radiating array of nerve fibers originating from a brain and that it exists in two portions, a supraesophageal ganglion and a subesophageal ganglion. And it goes on to discuss the functions of both parts. Very informative but also says the structure is a brain. So I am scrolling through this book and it seems like a really neat book, even has emergency procedures a tarantula owner should take if they notice bad signs and how to recognize them. But then I come across a tiny section as I'm scanning through it, so let me painfully switch back and forth to type it out because this part may stir up some heat ->that I'm not going to argue here<- , but if you were on my first thread you may start shaking your head. Honestly I dont want to stir up because I know now it is SENSITIVE, but I've seen it from a professional source and I'm going to at least share and move on to the rest of tonight's findings with you guys. So here it is straight from the book and hold on to your britches, "Although several groups of spiders seem to be able to form images and derive useful information from their eyes, it is not known as to what extent tarantulas possess that capability. However, wild tarantulas, or those not accustomed to handling, do react to motions around them." It goes on to explain their fight and flight and what is known they can perceive. You may have missed what I read in this: "those not accustomed to handling". To me this seems like the authors are inferring that they believe some tarantulas are accustomed and some are not. WHOA LOWER THE WEAPONS. As a disclaimer, I do not encourage or condemn handling. I am just showing what I find. You, the reader, may understand why I'm tiptoeing through this if you read my last thread. Handling as a whole is strongly not recommended on these forums. Moving on! Okay the last part of the book I noticed that I found interesting was talking about the vernacular term for a baby spider or young spider spiderling, also known as sling, to not be an officially sanctioned term for a wee one. This may have changed because the book was published in 2009. But if you know you can share the knowledge. You may think, so what? Well this is part of my findings hang in there. So I think, okay the forums aren't going to like part of what I found there so maybe I need a more general ruling from so many sources that we have condensed in one place. Sound familiar? Yep heading to Wikipedia! Not everything in Wikipedia is going to be accurate, they try to moderate but there's always that guy(or gal) who thinks it's funny to change it or add unsupported things. But here we go! First let's Google ganglion. My first result was about ganglion cysts. Oh my! No no no no no. Not what I'm looking for. So let's go to brain wiki first scan it, and then to the ganglion one. And again here you are: https://en.m.wikipedia.org/wiki/Brain And what do we see? A big beautiful heap of information! So let's scroll down and I'll point some things out: "Except for a few primitive organisms such as sponges (which have no nervous system) and cnidarians (which have a nervous system consisting of a diffuse nerve net), all living multicellular animals are bilaterians, meaning animals with a bilaterally symmetric body shape" okay why did I post this? Because you may not know what a bilaterial is. So they go on to say: "At a schematic level, that basic worm-shape continues to be reflected in the body and nervous system architecture of all modern bilaterians, including vertebrates. The fundamental bilateral body form is a tube with a hollow gut cavity running from the mouth to the anus, and a nerve cord with an enlargement (a ganglion) for each body segment, with an especially large ganglion at the front, called the brain. The brain is small and simple in some species, such as nematode worms; in other species, including vertebrates, it is the most complex organ in the body." So that says all bilaterals have certain structures in common, but a strong note is they note a ganglion as being a brain. And to scroll a bit further to see what they regard as exceptions "There are a few types of existing bilaterians that lack a recognizable brain, including echinoderms and tunicates. It has not been definitively established whether the existence of these brainless species indicates that the earliest bilaterians lacked a brain, or whether their ancestors evolved in a way that led to the disappearance of a previously existing brain structure." Okay well spiders aren't in those. And here is the last section I will look at for now on this page: "Two groups of invertebrates have notably complex brains: arthropods (insects, crustaceans, arachnids, and others), and cephalopods (octopuses, squids, and similar molluscs). The brains of arthropods and cephalopods arise from twin parallel nerve cords that extend through the body of the animal. Arthropods have a central brain, the supraesophageal ganglion, with three divisions and large optical lobesbehind each eye for visual processing." And that concludes that wikipedia considers tarantula ganglion as a form of a brain. But just real quick I'll click the link for ganglion and bring this up, "Ganglia provide relay points and intermediary connections between different neurological structures in the body, such as the peripheral and central nervous systems". Okay so the ganglia kind of functions like a most condensed basic form of a brain. Alright. So if you made it this far look how long that took? I can assure you I've been on this for over 7 hours. So why did I do all this? Because I have no life? Hey be nice! Shhh. Well I did it because I got conflicting information. I want to be overly detailed because I dont want anyone to think some of the things I have found is baseless arguing. So if you made it this far, can we as a community agree that they do have a brain even if it is a different form? Or can I influence people to agree that it is an acceptable vernacular term? I mentioned earlier how the slings vernacular term would be relevant so here it is now, even though sling is not an officially sanctioned term, this community does not seem opposed to using it to regard a spiderling. So is brain an acceptable vernacular term for the ganglion the tarantula has? Please don't just hit the disagree button because I won't know which part you are disagreeing with. I would much prefer a comment and maybe information that is hopefully linked to look further into. So I did all this to be more correct with a vernacular term? Uh.... >.> ... yes.