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Of Webs And Weed: Why NASA Drugged Spiders, And What We Learnt

Posted on 2 February 2023

Our story begins in the zoology department of Tübingen University in Germany. It’s 1948, and the zoologists of Tübingen have a humble ambition: to film spiders spinning their intricate webs for an educational documentary. 

The spiders are not playing ball.

For several days in a row, the scientists had stayed up past their bedtimes to film the arachnids building their traps. Each night they had fallen asleep, waking only to find that the spiders had constructed their webs off-camera. If only the spiders could somehow be made to weave their webs a little earlier in the night. It was then that the zoologists had an idea: drug the spiders. 

They decided to hit up their pharmacologist buddy, Peter N. Witt, to see if he had anything that could make the spiders follow a more civilised work schedule. Witt was studying various psychoactive drugs at the time, including marijuana and mescaline, and was happy to lend them some. Witt wasn’t sure whether the drugs would have the intended effects on the spiders, but that wasn’t really what he was interested in. Sure enough, the zoologists returned to him disappointed and sleep-deprived. None of the drugs they used had made the spiders start weaving their webs any earlier. However, the drugs did seem to have another effect: the webs created by spiders receiving different drugs looked rather different from each other.

The web of a spider under the influence of an unnamed sleep-inducing drug. Witt noted that these spiders were more likely to omit the longest threads.
Spider Webs and Drugs, Peter Witt,

This outcome intrigued Witt greatly, so much so that he decided to transfer his research from humans to spiders immediately. Why was Witt so interested in the spiders? The human nervous system was extremely complex, but also variable between different individuals, as was human behaviour. This made the effects of different drugs on human behaviour difficult to interpret. Some would experience fantastic dreams, others a wide range of powerful emotions from the same drug without rhyme or reason. Spiders, on the other hand, were much simpler organisms. If the effects of different drugs translated to consistent, clearly observable change in behaviour (in this case manifesting as a change in the appearance of the web) then spiders could provide an important insight into what made each drug different. Spiders might even be useful for identifying small quantities of unknown drugs, such as in cases of poisoning. 

Witt got to work, and soon found that different drugs did indeed affect the spiders differently. For example, the stimulant benzedrine caused spiders to zigzag unsteadily while building the spiral part of the web, making it uneven. The stoned spiders, on the other hand, were able to spiral just fine, but would omit the first part of the spiral, only ever completing the central part of the web. Witt would publish his findings, but the relevance of the results was ultimately uncertain. As Witt was unable to interview the spiders, he could not be sure how the effects of the drug related to the human experience, and presumed that we would never know.

Spiders given benzedrine tended to produce more uneven spirals, while spiders given marijuana left more empty spaces within the framework.
Spider Webs and Drugs, Peter Witt,

Witt’s studies continued (you can find a list of all his papers here). In the 50s, scientists witnessed the first known arachnid acid trip when spiders were fed small flies loaded with LSD. These spiders reportedly seemed ’unaware of outside influences and concentrated on the job’, and produced ‘more perfect webs than when in a ‘normal’ state’. Spiders on depressants, on the other hand, ‘forgot’ to finish their webs.

Webs of spiders given mescaline (left, middle) and LSD (right). Photographing spider webs was hard back then, but the LSD web is not missing its spiral. Webs had to be sprayed with a chemical to make them easier to photograph, but even then many details were hard to capture.

Once again, aside from the obvious parallels with human behaviour, no firm conclusions were drawn about human relevance. For the record, even though it may have legitimate medical applications, we don’t advise using LSD for productivity purposes.  

Witt’s interest in spiders and their response to various drugs continued throughout his life, but it wasn’t until the 1990s that a truly big name in science got involved. If you’ve ever heard of this kind of spider research before, it’s probably in the context of this experiment. In 1995, NASA scientists published a study in which marijuana, benzedrine, caffeine or chloral hydrate (a sedative and hypnotic drug) were given to spiders, and the effects on their webs observed. What reason did NASA have for such an experiment? The article in which the results were published (found in an issue of NASA Tech Briefs) doesn’t go into detail about exactly how, if at all, the experiment related to space flight. However, unlike previous studies, NASA was able to apply modern computing and statistical methods. They digitised the web structures, and found that the structure of the web correlated with the toxicity of the substance being tested. Specifically, the more toxic the substance, the fewer sides of each web ‘cell’ the spiders completed. See if you can guess which is which.

Webs spun by spiders exposed to different drugs (drug names removed for suspense).
Using Spider-Web Patterns To Determine Toxicity

And here are the answers:

Using Spider-Web Patterns To Determine Toxicity

Did you guess right? Some may be surprised by the placement of one of the drugs here: caffeine. While marijuana and benzedrine – both highly controlled substances in most countries – clearly impair the spiders’ web forming abilities, the webs of spiders on caffeine are utterly hopeless. However, the spiders don’t lie – caffeine is at the very least quite a bit more toxic than marijuana (for benzedrine, the comparison is a bit harder to make due to lack of data). 

While we don’t know the exact dose of THC (the main active component of marijuana) needed to kill a human, we know that a rat needs to eat up to two grams of pure THC per kg of body weight to result in a 50% chance of death. For caffeine, it only takes 370 milligrams per kg to achieve the same effect. It doesn’t appear that the spiders were given pure THC either, so it no longer seems all that surprising that the spiders were more affected by the caffeine. Incidentally, it takes around 10 grams of oral caffeine to put most humans in danger of death (though this obviously varies based on factors like body weight), meaning you would need to drink anywhere between 50 and 100 cups of coffee in quick succession in order to receive a fatal dose.

Anyway, back to the spiders. NASA was interested in using them to test the toxicity of other chemicals, since testing them on higher animals was much more expensive and ethically questionable. However, the spiders clearly weren’t deemed to be useful enough, as they still aren’t a common feature of toxicology labs so far as I can tell (except maybe when it’s their venom being tested).

So, some seven decades on from Witt’s original experiment, did we learn anything useful at all? In science, all data is useful. To me, this story is a nice demonstration of how, when scientists talk to other scientists from different fields and follow their interests, their research can lead to interesting places. It’s just that sometimes, that place is an acid-tripping spider.

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    Title photo by Bence Balla-Schottner, Unsplash

    Spider Webs and Drugs:


    Using Spider-Web Patterns To Determine Toxicity:

    Toxicological Properties of Δ9-tetrahydrocannabinol and Cannabidiol:

    The acute lethal dose 50 (LD50) of caffeine in albino rats:

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