When science gets it really wrong...

[boina]

On an unrelated search I came across this little gem: Tarantulas secrete silk from their feet.
It was published in a peer reviewed and respected journal. Nevertheless it's of course a load of unmentionable things from a bull and I was ROTFLMAO reading it.

I just put it here for entertainment and to give a fantastic example of why people shouldn't believe things just because a scientific paper said so, not even a peer reviewed on. People on here tend to say: "It was scientifically published, therefor it must be true" much too often. A scientific result is only valid if it has been repeated a few times by independent researchers. And if scientists publish an opinion there's even less reason to 'believe' them. I mean this recent Avicularia revision put Heteroscodra in subfamily Aviculariinae and there's no way I'll buy that.

That publication above gave Dr. Perez-Miles on the other hand the opportunity to publish this neat refutation (in the same journal...)

 

[JoshDM020]

I mean this recent Avicularia revision put Heteroscodra in subfamily Aviculariinae and there's no way I'll buy that.

Im just asking so i can learn something today, other than the fact that im secretly sexist because my memory failed me once ( ) : Why dont you buy that? Is it because its an old world genus thats been stuck in a primarily new world subfamily, ooorrr?

 

[boina]

Im just asking so i can learn something today, other than the fact that im secretly sexist because my memory failed me once ( ) : Why dont you buy that? Is it because its an old world genus thats been stuck in a primarily new world subfamily, ooorrr?

Because the reasoning was rather weak. I don't remember all of it but it was about the shape of the scopulae and that does seem like a trait that can easily evolve twice as an adaptation to their arboreal environment.

Other traits however, like venom composition for example, put Heteroscodra firmly among other African tarantulas. It's venom does, however, differ vastly from Avicularia venom. Then there are urticating hairs, a trait that's ubiquitous in NW species, but completely missing in Heteroscodra. Why would you put scopula shape over these presumably much less environmentally influenced traits? It doesn't make sense.

And yes, taxonomic groups should be monophyletic, meaning all members are supposed to sit on the same evolutionary branch. So for Avicularia and Heteroscodra to belong to the same subfamily, this subfamily with all its defining traits must have existed before Africa and America split up. While that's not impossible I would require much stronger evidence to go for that hypothesis.

 

[miss moxie]

On an unrelated search I came across this little gem: Tarantulas secrete silk from their feet.
It was published in a peer reviewed and respected journal. Nevertheless it's of course a load of unmentionable things from a bull and I was ROTFLMAO reading it.

I just put it here for entertainment and to give a fantastic example of why people shouldn't believe things just because a scientific paper said so, not even a peer reviewed on. People on here tend to say: "It was scientifically published, therefor it must be true" much too often. A scientific result is only valid if it has been repeated a few times by independent researchers. And if scientists publish an opinion there's even less reason to 'believe' them. I mean this recent Avicularia revision put Heteroscodra in subfamily Aviculariinae and there's no way I'll buy that.

That publication above gave Dr. Perez-Miles on the other hand the opportunity to publish this neat refutation (in the same journal...)

We nerds have the strangest sense of humor to anyone on the outside looking in, I am 99.985% sure.

 

[sasker]

That publication above gave Dr. Perez-Miles on the other hand the opportunity to publish this neat refutation (in the same journal...)

That over-fed Grammostola mollicoma in one of the pictures is way too high above the surface. She could easily fall and rupture her abdomen. Don't these researchers ever visit Arachnoboards and participate in heated debates about handling?! What if someone new to keeping tarantulas saw these pictures and starts to think this is the right way to handle tarantulas? Bunch of pseudo-scientists!

 

[Ungoliant]

On an unrelated search I came across this little gem: Tarantulas secrete silk from their feet.

public domain art

 

[Michel Heytens]

On an unrelated search I came across this little gem: Tarantulas secrete silk from their feet.
It was published in a peer reviewed and respected journal. Nevertheless it's of course a load of unmentionable things from a bull and I was ROTFLMAO reading it.

I just put it here for entertainment and to give a fantastic example of why people shouldn't believe things just because a scientific paper said so, not even a peer reviewed on. People on here tend to say: "It was scientifically published, therefor it must be true" much too often. A scientific result is only valid if it has been repeated a few times by independent researchers. And if scientists publish an opinion there's even less reason to 'believe' them. I mean this recent Avicularia revision put Heteroscodra in subfamily Aviculariinae and there's no way I'll buy that.

That publication above gave Dr. Perez-Miles on the other hand the opportunity to publish this neat refutation (in the same journal...)

I saw that theres not much information over here about the Grammostola Mollicoma, Im from Uruguay, they are called "Arañas Pollito" translated it would be "Chicken Spider" I really dont know why they are called this way, anyway, if anyome is thinking about getting one, here are some facts from an uruguayan itself, first, they are extremely docile, you can go, catch a wild one, get her in the enclosure, give her a couple days to get comfortable and they are really easy to handle, even when messed around with, they are 90% pretty chill, their bite is kinda lame, a bee gave me more swelling and pain than the G. Mollicoma, they are black, after molting they'll have a dark brown color, wich will eventually turn black, they are pretty good eaters, I had one as my first T, a wild one that i captured myself, and the only time i got bitten was because i dropped some leaves over her while trying to fill his water container, and she bit me in my finger, no big deal, they can be handled, and dont tend to move a lot, so if a quicky sneaky T is a concern for you, dont worry, I would personally recommend them as beginner Ts, and they seem pretty "normal" the dont have bright colors, or weird shapes, but the more days she spends with you, the more you like them, if you have any doubts just ask, and if its withing my knowledge I will answer. Cheers.

Heres a Link to a quick review about spiders that live in uruguay, nothing crazy, but if you like to see them, here they are, its a photo gallery with a short description:http://cdf.montevideo.gub.uy/exposicion/aracnidos-del-uruguay

 

[Andrea82]

I saw that theres not much information over here about the Grammostola Mollicoma, Im from Uruguay, they are called "Arañas Pollito" translated it would be "Chicken Spider" I really dont know why they are called this way, anyway, if anyome is thinking about getting one, here are some facts from an uruguayan itself, first, they are extremely docile, you can go, catch a wild one, get her in the enclosure, give her a couple days to get comfortable and they are really easy to handle, even when messed around with, they are 90% pretty chill, their bite is kinda lame, a bee gave me more swelling and pain than the G. Mollicoma, they are black, after molting they'll have a dark brown color, wich will eventually turn black, they are pretty good eaters, I had one as my first T, a wild one that i captured myself, and the only time i got bitten was because i dropped some leaves over her while trying to fill his water container, and she bit me in my finger, no big deal, they can be handled, and dont tend to move a lot, so if a quicky sneaky T is a concern for you, dont worry, I would personally recommend them as beginner Ts, and they seem pretty "normal" the dont have bright colors, or weird shapes, but the more days she spends with you, the more you like them, if you have any doubts just ask, and if its withing my knowledge I will answer. Cheers.

Heres a Link to a quick review about spiders that live in uruguay, nothing crazy, but if you like to see them, here they are, its a photo gallery with a short description:http://cdf.montevideo.gub.uy/exposicion/aracnidos-del-uruguay

that's curious, i think i saw the 'chicken spider' being referred to as one from the Pamphobeteus genus. But it's Grammostola?

 

[cold blood]

I wish I had the face palm emoji

 

[Andrea82]

that's curious, i think i saw the 'chicken spider' being referred to as one from the Pamphobeteus genus. But it's Grammostola?

@Michel Heytens
here's the thread:
http://arachnoboards.com/threads/arana-polita-chicken-spider-diary.173405/

 

[EulersK]

On an unrelated search I came across this little gem: Tarantulas secrete silk from their feet.

There was actually a study by Foelix, Erb, and Rast that investigated what was seen - "Alleged silk spigots on tarantula feet: Electron microscopy reveals sensory innervation, no silk"

In short, the initial study saw strands coming from the spider's feet and assumed it was silk. The latter study actually took a closer look with an electron microscope and found that the strands were actually made of hemolymph. Turns out that there are chemoreceptors on the tarantulas feet with exposed nerves, and a result of that is hemolymph that constantly leaks.

 

[boina]

There was actually a study by Foelix, Erb, and Rast that investigated what was seen - "Alleged silk spigots on tarantula feet: Electron microscopy reveals sensory innervation, no silk"

In short, the initial study saw strands coming from the spider's feet and assumed it was silk. The latter study actually took a closer look with an electron microscope and found that the strands were actually made of hemolymph. Turns out that there are chemoreceptors on the tarantulas feet with exposed nerves, and a result of that is hemolymph that constantly leaks.

What? Hemolymph is leaking?? I can't get the full article, only the abstract, but that doesn't indicate any leaking of hemolymph, neither does it say anything about exposed nerves. It is just describing a sensory hair and so are the attached pictures. Are you really sure you didn't misunderstand something?

 

[EulersK]

What? Hemolymph is leaking?? I can't get the full article, only the abstract, but that doesn't indicate any leaking of hemolymph, neither does it say anything about exposed nerves. It is just describing a sensory hair and so are the attached pictures. Are you really sure you didn't misunderstand something?

Yeah, I've got access to the full article. I'm on my phone at the moment, but when I get home I'll quote the specific part that I'm referencing. If I forget, then feel free to tag me

 

[Sergic]

Not to intentionally steal @EulersK thunder, but I have access to the full text and am able to grab quotes now. Here is the relevant bit:

"However, although there is no secretion of silk, some other kind of secretion seems to exude from the “ribbed hairs”, which forms delicate short “trails” rather than threads (Peattie et al., 2011). Nothing is known about the chemical composition or the function of this substance, but it has been suggested that it may be receptor lymph oozing out of the tip of a “ribbed hair” (Foelix et al., 2012a). This is still an open question and needs further study. Considering the small quantities of these trails and the fact that they snap when the tarsus is lifted off the substrate, it is highly unlikely that they play any role in adhesion (Peattie et al., 2011)."

So not hemolymph, but there is some substance exuded from the "ribbed hairs".

 

[boina]

Not to intentionally steal @EulersK thunder, but I have access to the full text and am able to grab quotes now. Here is the relevant bit:

"However, although there is no secretion of silk, some other kind of secretion seems to exude from the “ribbed hairs”, which forms delicate short “trails” rather than threads (Peattie et al., 2011). Nothing is known about the chemical composition or the function of this substance, but it has been suggested that it may be receptor lymph oozing out of the tip of a “ribbed hair” (Foelix et al., 2012a). This is still an open question and needs further study. Considering the small quantities of these trails and the fact that they snap when the tarsus is lifted off the substrate, it is highly unlikely that they play any role in adhesion (Peattie et al., 2011)."

So not hemolymph, but there is some substance exuded from the "ribbed hairs".

So there's really something coming out of these receptors that may be hemolymph!! That's fascinating.

My appologies to @EulersK for disbelieving you and questioning your understanding - you were absolutely right.

 

[Andrea82]

Not to intentionally steal @EulersK thunder, but I have access to the full text and am able to grab quotes now. Here is the relevant bit:

"However, although there is no secretion of silk, some other kind of secretion seems to exude from the “ribbed hairs”, which forms delicate short “trails” rather than threads (Peattie et al., 2011). Nothing is known about the chemical composition or the function of this substance, but it has been suggested that it may be receptor lymph oozing out of the tip of a “ribbed hair” (Foelix et al., 2012a). This is still an open question and needs further study. Considering the small quantities of these trails and the fact that they snap when the tarsus is lifted off the substrate, it is highly unlikely that they play any role in adhesion (Peattie et al., 2011)."

So not hemolymph, but there is some substance exuded from the "ribbed hairs".

awesome! thanks for posting

 

[Sergic]

awesome! thanks for posting

Thanks. But @EulersK deserves the thanks for this. He found, read, and mentioned the paper. I just have access to journal articles and had enough free time to read the paper after seeing he mentioned it.

 

[Andrea82]

Thanks. But @EulersK deserves the thanks for this. He found, read, and mentioned the paper. I just have access to journal articles and had enough free time to read the paper after seeing he mentioned it.

woops, sorry about that @EulersK
thank you

 

[efmp1987]

So there's really something coming out of these receptors that may be hemolymph!! That's fascinating.

My appologies to @EulersK for disbelieving you and questioning your understanding - you were absolutely right.

Possible it exerts a negative pressure creating some kind of vacuum against a surface?

 

[efmp1987]

I found that article before and thought it was ridiculous. Chitinous / Keratinous layers like hair/setae have practically zero circulation and thus cannot sustain some form of anatomical organ or structure.

If a peer review can get it wrong, more so practices (example: ICU ) not backed by anything at all. I still choose to be somewhat unorthodox as to what is right and what is not.