Vegetarian spider... what the hell?

[Rosinbio]

This is just to weird. How does something like this happen?

Although this quote:


Contradicts this one:

Which would mean the spider is an omnivore and not a vegetarian, it still is very weird to me. How does a spiders fangs adapt to eat fruit?

I have been surfing the Internet In a , so far unsuccessful attempt, to find Meehan's e-mail address, in order to request a PDF of the just published article in the October issue of Current Biology, about this sensational "vegetarian" spider. (Never mind. One way, or another, I shall eventually find Meehan's e-mail in the online information I regularly receive from the journal. The information provides free summaries, as well as e-mails of the corresponding authors. But, so far I only have the online information about the September issue.)

What I have found, instead, is that the Internet is now full of information about this sensational story, and reading some of it helped me clarify for myself some confusion I had in my mind about this story.

Turns out that the "new" story is not new, and the "buds" the spider is reported to feed on, are not buds, the way the term is used in botany. The "buds" are special growths that the plant produce at the tips (!) of its leaves. They feed the ants that maintain a very long known symbiosis with the plant. The spider has also been observed to feed on nectar, that is apparently produced near the "buds", and is eaten by the ants.

What is new about the story is that, although exactly the same species of spider, had originally been discovered feeding (not very often) on the "buds" in Costa-Rica (in 2001) there is some new information about the species.
It has by now been discovered that the spider feeds almost exclusively on the "buds" and nectar (produced by the special acacia-bushes) in Mexico, and that such feeding is common mostly during the dry season (when, I imagine, the spiders may need more water). The new information is further bolstered by biochemical tests, which show that substances found in the spider's tissue resemble much more closely substances found in the tissues of the ants (that feed on the "buds" and nectar), than substances found in the tissues of other spiders.

The biochemical tests on their own, cannot of course, exclude the possibility that the spider, that also feeds ( though more rarely) on the ant's larvae, could obtain those substances indirectly from the ants, that feed on the "buds". There appear to be some problems about how the spider eats the buds which contain much more material that it cannot liquefy (compared to animal prey).

At this point I am, therefore very much interested in seeing the new publication in Current Biology.

 

[EHocking]

I have been surfing the Internet In a , so far unsuccessful attempt, to find Meehan's e-mail address, in order to request a PDF of the just published article in the October issue of Current Biology,(Never mind. One way, or another, I shall eventually find Meehan's e-mail in the online information I regularly receive from the journal. The information provides free summaries, as well as e-mails of the corresponding authors. But, so far I only have the online information about the September issue.)

Your powers of observation are obviously lacking.
There is a link to his email right next to his name on the online summary of the paper at the Current Biology site...(that would be the Oct 13 link I provided earlier)

...reading some of it helped me clarify for myself some confusion I had in my mind about this story.

Turns out that the "new" story is not new,

This is a discovery for you? This information was in a post of mine that you just responded to...

...What is new about the story is that, although exactly the same species of spider, had originally been discovered feeding (not very often) on the "buds" in Costa-Rica (in 2001) there is some new information about the species.

You misunderstand the information on the Costa Rica spiders. They are found on less than 5% of acacia trees there, but there diet consist of 60% beltian bodies...

It has by now been discovered that the spider feeds almost exclusively on the "buds" and nectar (produced by the special acacia-bushes) in Mexico, and that such feeding is common mostly during the dry season (when, I imagine, the spiders may need more water).

Again, your reading of the paper is in error.

"spider occupancy was higher in wet season than dry season sampling"

"[on diet]...Especially during the dry season they also occasionally cannibalize other B. kiplingi. "

The new information is further bolstered by biochemical tests, which show that substances found in the spider's tissue resemble much more closely substances found in the tissues of the ants (that feed on the "buds" and nectar), than substances found in the tissues of other spiders.

The biochemical tests on their own, cannot of course, exclude the possibility that the spider, that also feeds ( though more rarely) on the ant's larvae, could obtain those substances indirectly from the ants, that feed on the "buds".

Cite?
"Meehan confirmed his results by analysing the chemical make-up of the spiders' bodies....Meehan also considered the ratio of two carbon isotopes, C-13 and C-12. Meehan found that the vegetarian spider and the Beltian bodies had virtually identical ratios, as is usually the case between an animal and its food. "

There appear to be some problems about how the spider eats the buds which contain much more material that it cannot liquefy (compared to animal prey).

Meehan conjectures that a bacteria that aids vegetable digestion in the ants is taken up by the spiders when they prey on these ants. He is yet to determine if this bacteria is passed on to the spider's offspring, or if the offspring has to acquire the bacteria by eating larvae themselves.

 

[Humanzee]

"Meehan conjectures that a bacteria that aids vegetable digestion in the ants is taken up by the spiders when they prey on these ants. He is yet to determine if this bacteria is passed on to the spider's offspring, or if the offspring has to acquire the bacteria by eating larvae themselves. "

Neat! I was wondering how the spiders could efficiently eat "the vegan way". Very interesting.

 

[davefoc]

I thought this was a very interesting story also.

True bugs (Hemiptera) can be either carnivorous or vegan depending on the species. These are sucking insects that seem to eat in a way similar to spiders in that everything they eat is liquid.

It has surprised me a bit that there weren't any spiders, (which is a pretty diverse group that have existed for a very long time) that had evolved to be vegan.

The difficulty for spiders I guess is that their digestive juices have very specifically evolved to target animals and not plants. In this case the target food has evolved to be a source of ant sustenance. And ants probably prefer foods that are a ready source of nutritious liquids to fill their crops with. So maybe the digestive juices of the spider in question aren't particularly effective at digesting the beltian bodies but they already can provide nutrition to a spider in a form that it can suck up without being predigested by digestive juices pumped into it the way a spider pumps its digestive juices into its prey.

 

[EHocking]

I thought this was a very interesting story also.

True bugs (Hemiptera) can be either carnivorous or vegan depending on the species. These are sucking insects that seem to eat in a way similar to spiders in that everything they eat is liquid.

It has surprised me a bit that there weren't any spiders, (which is a pretty diverse group that have existed for a very long time) that had evolved to be vegan.

The difficulty for spiders I guess is that their digestive juices have very specifically evolved to target animals and not plants. In this case the target food has evolved to be a source of ant sustenance. And ants probably prefer foods that are a ready source of nutritious liquids to fill their crops with. So maybe the digestive juices of the spider in question aren't particularly effective at digesting the beltian bodies but they already can provide nutrition to a spider in a form that it can suck up without being predigested by digestive juices pumped into it the way a spider pumps its digestive juices into its prey.

From what I can gather from the articles that I have found, the spiders actually eat i.e. chew, swallow, digest, the Beltian bodies, rather than feed like other, carnivorous, spiders i.e. inject, liquify, suck.

From the Scientific American article,
It is noted that Beltian bodies are 80% fibre, and Meehan notes that,
" it is the digestion process that has the researchers tied up in knots "
...
"the peculiar food choice may have gotten started as these arachnids fed on the ant larvae, which are, themselves, fed primarily Beltian bodies. Researchers are now looking for bacteria in these ant larvae that would help the spiders digest the plant material. They also hope to establish whether such bacteria are now passed along to spider offspring or if they must be acquired individually by eating the ant larvae. "

So the current line of research is not just to discover just how the spiders are able to digest an herbivorous diet, it seems that they have yet to establish the digestion process of the ants (larvae).

 

[davefoc]

Thanks for the response Ehocking.

The original paper is now available only for a fee. I think I'll read it the next time I go to the college library near me.

Your comment about the possibility that the spider could chew led me to read more about spider anatomy. I was under the impression that spiders could only drink fluids. That was wrong. Apparently it is true for cobweb spiders (the group that includes the widow spiders (Latrodectus)). But for most spiders it is not. Most spiders can use their chelicerae to shred and mash food before ingesting it.
http://www.uky.edu/Ag/CritterFiles/casefile/spiders/anatomy/spideranatomy.htm

While this may be the only vegetarian spider, there are vegetarian arachnids like the spider mites. There are even carnivorous butterflies.
http://ngm.nationalgeographic.com/ngm/0306/feature6/index.html

 

[Rosinbio]

Your powers of observation are obviously lacking.
There is a link to his email right next to his name on the online summary of the paper at the Current Biology site...(that would be the Oct 13 link I provided earlier)This is a discovery for you? This information was in a post of mine that you just responded to...You misunderstand the information on the Costa Rica spiders. They are found on less than 5% of acacia trees there, but there diet consist of 60% beltian bodies...
Again, your reading of the paper is in error.

"spider occupancy was higher in wet season than dry season sampling"

"[on diet]...Especially during the dry season they also occasionally cannibalize other B. kiplingi. "
Cite?
"Meehan confirmed his results by analysing the chemical make-up of the spiders' bodies....Meehan also considered the ratio of two carbon isotopes, C-13 and C-12. Meehan found that the vegetarian spider and the Beltian bodies had virtually identical ratios, as is usually the case between an animal and its food. "
Meehan conjectures that a bacteria that aids vegetable digestion in the ants is taken up by the spiders when they prey on these ants. He is yet to determine if this bacteria is passed on to the spider's offspring, or if the offspring has to acquire the bacteria by eating larvae themselves.

Thanks for reminding me that you provided a link to the 2009 publication by Meehan et al. in Current Biology, which I had clean forgotten (by the time I checked the latest information from the journal in my inbox, found that it provides free summaries, with e-mails of corresponding authors, but did not yet have the information about the October issue, surfed the Internet searching for Meehan's e-mail, but was able to find the correct Meehan only after googling "Meehan and spiders", which led me to a big fanfare all over the Internet about his new discovery, but remembering that the discovery of spiders of this species feeding on acacia "buds" had already been made in 2001, by someone else, who might, or might not, have published it then).

I have now searched your link, found it, opened it, found Meehan's e-mail and requested a PDF. I found out long ago that instead of purchasing scientific article not available for free, you can simply request a PDF from the corresponding author, but you need his e-mail address. Authors usually acceed to such requests.

In view of the way I had to roam through material about this scientific news item that is completely new to me (while being constantly bombarded with almost endless scientific news items about various other matters that interest me), I am not only quite pleased with my observation powers, but am often amazed to find I still retain them. It appears that the only error I might have made concerns the effects of the season, I'm however, not going to recheck all the posts in this thread, to find out what exactly they say about these effects, but wait to see the PDF of the 2009 publication, which I hope Meehan will be kind enough to e-mail to me. Should I receive it, I wonder whether posting a copy to this thread, for the benefit of others, would be considered breaking copyright rules, or not.

 

[jasonpatterson]

Should I receive it, I wonder whether posting a copy to this thread, for the benefit of others, would be considered breaking copyright rules, or not.

Yes, it would.

 

[EHocking]

...but remembering that the discovery of spiders of this species feeding on acacia "buds" had already been made in 2001,

You mean remembering that you had read it here, a number times, but whatever....

by someone else,

Eric Olson, the co-author of the paper in Current Biology (name was right next to Meehan's name, shouldn't have been that hard to miss since he's mentioned in EVERY article on the subject...

who might, or might not, have published it then).

Well, unlike yourself, I'm not in the academic world, but it was a simple task to find his CV. You'll love the irony that his initial paper on the subject was rejected in 2005 by Nature. Email him to get a preview - he may have submitted it to Ecology since then, or decided to co-author with Meehan instead.

It appears that the only error I might have made concerns the effects of the season,

.....
Oh, I just couldn't be bothered any more.<snip>

 

[EHocking]

Reading on, Olson DIDN'T make the discovery in 2001 - his research assistants did.

Here's an article in Costa Rica Times where he 'fesses up to being badgered into observing the spider on the acacia trees.

A classic tale of how scientific discoveries are made.

It reminds me of the seemingly forgotten influence that John Gould played in Darwin's formulation his famous theory, when Gould pointed out the differences in the finches from the Galapagos that Darwin had presented to the Museum of Zoological Society.

 

[Rosinbio]

You mean remembering that you had read it here, a number times, but whatever....Eric Olson, the co-author of the paper in Current Biology (name was right next to Meehan's name, shouldn't have been that hard to miss since he's mentioned in EVERY article on the subject...Well, unlike yourself, I'm not in the academic world, but it was a simple task to find his CV. You'll love the irony that his initial paper on the subject was rejected in 2005 by Nature. Email him to get a preview - he may have submitted it to Ecology since then, or decided to co-author with Meehan instead......
Oh, I just couldn't be bothered any more.<snip>

So now you are trying to control how I budget my time? Don't even think about it!

 

[Floyt]

So now you are trying to control how I budget my time? Don't even think about it!

It would be pointless anyway - what with

Obsessing About The Bee Dance Conspiracy - 50%
Massaging Your Ego - 50%

you don't actually have any wiggle room left...

 

[Rosinbio]

It would be pointless anyway - what with

Obsessing About The Bee Dance Conspiracy - 50%
Massaging Your Ego - 50%

you don't actually have any wiggle room left...

Had I bothered to remember your user's name, I would have been able to identify you long ago as one of those arrogant little "control-freaks" and "put-down artists", that seem to inhabit almost every website.

I don't bother with your kind of bullies!

 

[Rosinbio]

Yes, it would.

Are you quite sure?

I discovered long ago that the interests of the publisher and the author clash here. The publisher is interested in making as much money as he only can out of his publication. But the author is interested in having as many people as possible read his publication. He is, therefore, allowed to send a full-text PDF, to any one who requests it, and would usually be pleased to do so for anyone who wants to read the work, but would not spend money to purchase a copy from the publisher, or schlep to a special library which has a subscription, and which he is also free to use.

This is permissible to the author, because it is covered by what is known as "fair use". I, therefore, assume that the author would be free to post a PDF to this Forum, if he chose to do so. Why shouldn't I be free to post here a copy of a PDF that the author e-mails me? To simplify matters, I could even ask his permission!

The publisher should be satisfied to earn a profit from individuals, as well as libraries and institutions, that subscribe to the journal! I, therefore, wonder where exactly does "fair use" end and "copyright law" kick in.

 

[davefoc]

Are you quite sure?

I discovered long ago that the interests of the publisher and the author clash here. The publisher is interested in making as much money as he only can out of his publication. But the author is interested in having as many people as possible read his publication. He is, therefore, allowed to send a full-text PDF, to any one who requests it, and would usually be pleased to do so for anyone who wants to read the work, but would not spend money to purchase a copy from the publisher, or schlep to a special library which has a subscription, and which he is also free to use.

This is permissible to the author, because it is covered by what is known as "fair use". I, therefore, assume that the author would be free to post a PDF to this Forum, if he chose to do so. Why shouldn't I be free to post here a copy of a PDF that the author e-mails me? To simplify matters, I could even ask his permission!

The publisher should be satisfied to earn a profit from individuals, as well as libraries and institutions, that subscribe to the journal! I, therefore, wonder where exactly does "fair use" end and "copyright law" kick in.

I am not part of the JREF management but I think it is very likely that jasonpatterson is right with regard to this. If one were to put something like this on JREF one would need at a minimum to get a sign off from the copyright holder and then convince one of the forum gods, possibly Darat himself, that the sign off was legitimate. You might be right about the interests of the various parties but this is not the same as a sign off by the copyright holder.

 

[EHocking]

Are you quite sure?

.. are you sure?

...I, therefore, wonder where exactly does "fair use" end and "copyright law" kick in.

It doesn't appear that you are...

But, being ever the helpful Forumite that I am,

Copyright clauses - articles in Current Biology.
Upon acceptance of an article, authors will be asked to transfer copyright. .... After transfer of copyright, authors retain rights as discussed below.

Authors’ rights



As an author you (or your employer or institution) may do the following:

• make copies (print or electronic) of the article for your own personal use, including for your own classroom teaching use;
• make copies and distribute such copies (including through e-mail) of the article to known research colleagues, for the personal use by such colleagues (but not for commercial purposes as described below)
• ....

 

[jasonpatterson]

The publisher should be satisfied to earn a profit from individuals, as well as libraries and institutions, that subscribe to the journal! I, therefore, wonder where exactly does "fair use" end and "copyright law" kick in.

The idea of fair use is part of copyright law. In that case of something factual like this, the rules are fairly loose (that is, they allow for quite a bit of use.) They also aren't clearly written out anywhere for people to go down a checklist and say, "Yep, that's legal."

You would be perfectly safe in posting excerpts from the article to back up an argument you had made or in receiving a copy of the article from the author (assuming the author agreed that your intent fit the requirements that he/she agreed to when transferring the copyright to the publisher.)

What we do here doesn't qualify as educational or research use, so the rules that publishers follow regarding fair use are more restrictive as well, but again there is no clear rule about it. For educational purposes, publishers and educators have agreed to allow a teacher at an educational institution, you can take a legally obtained copy of the article and make copies for your students, for example (with some restrictions concerning the length, purpose, and frequency of use.) They are not allowed to take those copies and further distribute them, however.

You would not be safe in posting the whole article here because it's only purpose in being posted here would be to circumvent the fee system set up by Current Biology. In that you would be no different than someone who illegally posted a legally obtained mp3 for free distribution (suppose it's on a music theory forum so that the comparison is valid.) You would not be safe in going to a library and copying the work from the Current Biology issue and posting it here either (that is, from the copyright holder.)

Finally, copyright law exists so that the copyright holder can make money from intellectual labor. If you want to debate whether that is the best system to use, that's fine, but that's the way the law is, so at the moment your opinion about how Current Biology should be making money is irrelevant.

 

[Kotatsu]

Are you quite sure?

Depending on the publisher of the journal, there are differences in degree of how adamant they are in pursuing people who, essentially, republish things without the publisher's permission. While you can often find PDF copies of a certain author's publications on his own webpage, and places like scratchpads.eu host literature lists with PDFs on a variety of groups (1), I have heard of cases where people doing so have received, at least, stern letters from their publisher, advising them to stop doing so. The Scratchpad crew, as I understand it, allows it as long as they are not informed about it, so that they can cite plausible deniability in case publishers get nasty...

Nevertheless, those, I would say, are cases where it might be reasonable to assume that posting a PDF should be allowed (even if it is not), albeit perhaps with some delay. This is an entirely different situation.

---
(1) If you haven't looked at it: do so! It is an excellent taxonomy and biodiversity data page!

 

[Kotatsu]

I have now read the Current Biology article, and some other papers referred to therein, and it seems we can put Rosinbio's fears of the authors being mistaken to rest. Apart from close observations, and "high definition videography", there is also extensive and convincing evidence from stable-isotope analysis of the ants, the plants, the spiders, and other spiders in the area:

Stable-isotope analysis confirmed B. kiplingi herbivory [...] [T]issues of herbivores tend to have lower ¹⁵N:¹⁴N ratios (expressed as δ¹⁵N) relative to carnivores, whereas consumers tend to match ¹³C:¹² ratios (δ¹³C] of their foods. Mexican B. kiplingi specimens had δ¹⁵N profiles averaging 4.8% lower than those of other jumping spiders from surrounding vegetation, but only 2.1% and 2.9% higher than ant workers and Beltian bodies, respectively. B. kiplingi spiders and ant workers had δ¹³C signatures virtually identical to those of Beltian bodies, whereas other spiders exhibited δ¹³C values that did not match those of the Beltian bodies.

They continue by noting that 89 +/- 13.2% of the C and N comes directly from the plants, and 8 +/- 7.9% comes indirectly from the plant-eating ants, giving the diet of the spider a heavy vegetarian slant. This was established by methods unfamiliar to me, but which can be found in the supplementary material, which I have not yet read. They continue:

Individuals of all age-sex classes had similar diets, suggesting that spiders in this population are near-total vegetarians throughout their lives.

But note that Costa Rican populations had a larger proportion of animal prey in their diet.

There is no end of interesting stuff in this article, though. They note, further, that the range of this species "coincides with that of ant-acacia systems throughout Mesoamerica", and that they are almost exclusively found on these plants. They speculate that, as the ants keep most other insects away from the acacias -- including, presumably, ones that might feed on the spiders -- the spiders may have "achieved herbivory by exploiting plant goods exchanged for animal services", which sort of makes sense. They can't eat too many of the ants, because then the acacia-ant system would be disrupted, and predators on the spiders would be introduced into the system. But they still need to feed on something, and the Beltian bodies are available.

Th article refers to two other cases of omnivory among spiders, though in neither case are these as elaborate as in Bagheera kiplingi. I have not yet read these articles (references below), but apparently some juvenile orb-weavers eat pollen which collect on their nets (Smith & Mommsen, 1984), though Meehan et al. suggests that this is more or less an accident, as they ingest them only when recycling their nets. Jckson et al. reported that 31 of 90 studied species of jumping spiders supplemented their diet with nectar, and apparently (from the abstract) did so to get sucrose, rather than water.

In all, a very interesting field, and the presence and wide spread of nectarvory in the Salticidae could certainly make the transition to herbivory more plausible, if there were already species that supplemented their diet with non-animalian food.

---
Jackson, Pollard, Nelson, Edwards & Barrion (2001): Jumping spiders (Araneae: Salticidae) that feed on nectar. Journal of Zoology 255, 25-29.

Meehan, Olson, Reudink, Kyser, Curry (2009): Herbivory in a spider through exploitation of an ant-plant mutualism. Current Biology 19, R892-R893.

Smith & Mommsen (1984): Pollen Feeding in an orb-weaving spider. Science 226, 1330-1332.

 

[EHocking]

So now you are trying to control how I budget my time? Don't even think about it!

How ungrateful of you.

The information I supplied on Olson was in response to this post by you,

...about his new discovery, but remembering that the discovery of spiders of this species feeding on acacia "buds" had already been made in 2001, by someone else, who might, or might not, have published it then).

I was providing help on where you could source information regarding the original discovery, since you seemed unable to do the search for your self.