Planet earth spider fact of the day

Their conclusion was that there are 25m tonnes of spiders around the world and that, collectively, these arachnids consume between 400m and 800m tonnes of animal prey every year. This puts spiders in the same predatory league as humans as a species, and whales as a group. Each of these consumes, on an annual basis, in the region of 400m tonnes of other animals.

Somewhere between 400m and 500m tonnes is also the total mass of human beings now alive on Earth.

Here is the Economist article.


One creepy thing about spiders is how they go through boom and bust cycles. About 15 years at the Lake Balboa park in the San Fernando Valley (not normally an insect-intensive place), the tall trees lining both sides of the Los Angeles River were completely encased in opaque spider webs for a hundred yards or so.

I was visiting George Mason university once and masses of spiders dropped from the ceiling in a classroom in the spring. I visited the same classroom years later, at about the same time, and masses of spiders dropped from the same room, the same spot, the same ceiling. I figured it was either a well-established student prank, or, more likely in today's PC environment, just a place where communal spiders of some sort (did they escape the Biology department?) must live and reproduce, and every year they come out in a swarm for reasons known only to them and biologists. True story. Watch your back if you have arachnophobia (a Greek word that means 'spider fear').

Bonus trivia: the Sydney funnel-web spider (Atrax robustus), found only in Sydney, is the most dangerous spider in the world, but they have antivenom and they are quite shy, as I was told when visiting. They are often mistaken for the less venomous but still dangerous Sydney brown trapdoor spider (Misgolas rapax).

Really, that's what 'arachnophobia' means? What does 'claustrophobia' mean? How about moussaka?

Potential therapy for stroke victims based upon funnel web venom:

Don't you think it's more likely that these were moth/caterpillar nests?

Thanks Tyler,

I was already having trouble sleeping tonight.

Save the planet - kill some spiders?

What would Peter Singer say about this and does it depend on how much the spider-victims suffer? (That's a serious question)

Outside cephalopods, arachnids are the most intelligent invertebrates. Jumping spiders out-perform primates on certain intelligence tests. In contrast the typical insect prey, like flies or beetles, are very stupid in comparison. And because spiders are so small it takes significantly fewer insects to support a spider mind than a mammalian insectivore.

Conclusion: There's no consistent and rational ethical axioms that accept anteaters, but not spiders.

And before any smart alec comes in, spider related human fatalities are virtually unknown in modern times. The vast majority of diagnosed spider bites come from other insects or infection.

"And before any smart alec comes in, spider related human fatalities are virtually unknown in modern times. The vast majority of diagnosed spider bites come from other insects or infection."

LOL, where do you live? Medical care keeps most spider bites from being fatal, but they are still far more hazardous to humans in my area than snakes are. Brown recluse spiders bite hundreds of people per year and the bites can result in serious injury if you don't get medical attention within a few hours.

And Spiders still manage to kill as many Americans every year as rattlesnakes, alligators and sharks combined. Roughly 7 per year. Granted, those are still low numbers for 300 million Americans, but saying that "spider related human fatalities are virtually unknown in modern times" seems a bit hyperbolic.

7 deaths per year. So they are on a par with Islamic terrorists deaths in the US.

I think we need a ban on people travelling to the US from countries known to have a lot of spiders.

Boonton wins the thread.

JWatts, do you have a citation on that? I found one unsourced Google link... and also a bunch of other links that suggest that there have been at most two or three spider bite deaths in the US over the past decade - forget 7 in a year. Wondering if the statistic is actually accurate.

"I think we need a ban on people travelling to the US from countries known to have a lot of spiders."

No, it's wiser to pursue the European approach to spiders and wait till they're killing people in airports and outside parliament to the extent that soldiers become familiar sights on the street before a ban is imposed.

Europe wouldn't have any problems at all if they banned immigration from Somalia but not Pakistan and made sure immigrants were not allowed to use laptops on their way but could use smart phones.

Sure, but why should we accept anteaters either? In a consistent Singerian world, do we not have a moral obligation to prevent cruelty on a planet-wide scale irrespective of species? Spiders are particularly cruel given the enormous number of thinking organisms they consume. Those organisms may not think very well but it would be speciest to privilege higher forms of life over bugs.

Therefore, to be consistent Singerians we should aim to reduce, painlessly, spider populations to the lowest possible number. Ideally, these predators should be confined to laboratories like smallpox - without, of course, being allowed to go extinct. And feed some sort of vegan insect substitute. After all, insects can and do suffer as far as we can tell. We have an obligation to reduce that suffering as much as possible. All animals have rights. If spiders violate other organisms' rights to life, liberty and happiness they need to be restrained.

The greatest happiness to the greatest number of organisms regardless of species demands no less.

Weighing organism well-being regardless of intelligence or some other measure of complexity devolves into a reductio ad absurdum. In almost every case the right answer would be to replace as much biomass as possible with bacteria. Orders of magnitude more bacteria can be sustained on the same resources as a single eukaryotic cell, let alone a large multicellular organism.

If we simply count up organisms, without distinguishing between them, the joy of a successful strep throat infection outweighs the tragedy of the holocaust.

We have yet to completely destroy smallpox. However counting bacteria might be a little hard. How do bacteria differ from their siblings in a way that the skin on my left hand differs from my right?

But by all means, let's consider their intelligence. Spiders are killing *a*lot* of insects. That is a small amount of intelligence over a very large number of organisms. What is more it is not really how clever they are that matters but how much they suffer. Do insects suffer? Well a human has just been convicted for boiling a lobster so the law clearly accepts they can and do - under the influence of Singer.

So the case seems strong. And of course if the argument is so easily reduced to absurdity it suggests the assumptions are not good ones.

Anteaters are relatively cuter and don't creep me out.

Why do philosophers get so nonsensical and abstract that my human emotion of being creeped out doesn't count because it's not "consistent or rational." It's why moral philosophy is so stupid.

Actually it is not that moral philosophy is stupid, it is that they are gutless.

This is simply a consequence of Spock's Law - every Star Trek episode has to have a human-alien hybrid because, basically, otherwise you support the Klan. When ST started doing human-alien hybrids, it was a commentary on the segregation of the US at the time. Love trumps hate, you see. Now if you suggest that perhaps this is implausible, it is virtually a hate-crime. This is especially odd because SF people are usually sensible on the idiocy of the 50s pulp covers that had an improbably clad girl menaced by a tentacled alien. Of course that alien is further away from humans than humans are from a squid and so is unlikely to lust for the human female form, but you can't mention that when it comes to Star Trek and their love of inter-species breeding.

This is taking a while but I am getting there - in the same way, you cannot raise disgust as a moral concept because the first place people will apply it is to homosexuality. And that is a Thought Crime. It may be no more or less valid to say that spiders creep you out than it is to say that male-on-male kissing or anal sex is, like, gross, but if you allow one you have to allow the other. So we are allowed neither.

So much wrong here, but I did get a chuckle out of it.

If you like jumping spiders and appreciate science fiction, you should read Children of Time.

We had an infestation of bedbugs a few years back. Nothing got rid of the god-awful pests until some daddy-long-legs spiders moved into the house from the garden. And then-- bedbugs all gone. I occasionally find one of these little carnivores in an odd corner of the house-- there are probably enough bugs of other kinds in the house for them to survive off of. As long as they stay out of my own space I leave them alone. In fact I'd pin a medal on them if I could.

From Wikipedia

Philosopher Peter Singer has argued that intervention in nature would be justified if one could be reasonably confident that this would greatly reduce wild animal suffering and death in the long run. In practice, however, Singer cautions against interfering with ecosystems because he fears that doing so would cause more harm than good

It is interesting to see Peter Singer acknowledge the limits of his information. Such modesty reflects well on him.

However it is interesting that these limits do not apply to his work on humans. Consider his interesting claim that we should donate all our money above subsistence to aid the Third World. He does not consider whether or not such aid does any good or if impoverishing the West wouldn't in fact impoverish the Third World even more. He wants to give some primates human rights without properly considering the unforeseen consequences of doing so. He wants to kill disabled children even though there is a clear slippery slope - Canada has started allowing doctors to kill organ donors for instance.

Why do these limits only apply to insects?

Is there a single historical example of a large economy 'impoverishing' itself due to excessive charitable giving?

Aw, let him go. SMFS is having so much fun crushing the easy target that is Singer.

Is there a single historical example of malevolent AI killing all of humanity?

There's your spectrum in a nutshell: excessive charitable giving is pretty much like malevolent humanity-destroying AI

Unforeseen consequences are largely unforeseen. But I would think so. Britain largely abandoned the Empire because they decided it was immoral. They then put up with the Communists using the Trades Unions to destroy large parts of the economy because they felt bad about The Ragged Trousered Philanthropist. And all of the West has been flirting with bankruptcy because they do not want to tell the feckless to get a job or single mothers to stop being sluts.

The West could have bases on Titan by now but we all decided to subsidize pathological life styles instead.

Keep it coming, more laughs!

Britain abandoned its empire for entirely rational reason: it was costing them money, not making money. The ethical reasons were just window dressing. If the empire had been a profit center rationalizations for keeping it would have been found.

Good work by the whales given their relatively small numbers compared to humans or spiders, although I suspect we're mostly talking about lame AF baleen whales slurping up plankton versus orcas and sperm whales massacring penguins and giant squid and the like.


What is striking to me is that a spider apparently eats 16x its body weight a year. Moreover, my naive guess is it is energy-rich food (bugs).

Compare to a human who is apparently (on average) eating 1x its body weight in prey, and I'd guess something like 7x its body weight in grain, fruit, and vegetables.

The striking thing to me is the human is warm-blooded and has a big brain and other features that would make me think it is much less energy efficient than the spider, but it seems to be more efficient. Perhaps this is the cost of spinning webs.

Humans dig minerals out of the ground to make our tools. Spiders transform food into directly into webs.

Indeed. For a spider, perhaps we should consider her web (if we could define it clearly) to be part of her "body" mass.

But then, we could say similar things about beavers and dams, and humans and their houses. Or farms.

No, we could not


"""The team isn’t sure how the graphene and carbon nanotubes end up in the silk. One possibility is that the carbon coats the outside of the strands, but Pugno thinks that would not be enough to account for the increase in strength. Instead, he believes the spiders mop up materials in their environment and incorporate them into the silk as they spin. This comes at a cost, however – four of the spiders died soon after being sprayed. At this early stage it’s not clear how such a material will be used, but one possibility is a giant net capable of catching falling aircraft, suggests Pugno."""

As a proportion of their body weight spiders contain much more "expensive tissue". E.g. spiders have much larger brains relative to their body size than any mammal. Being a large organism affords certain economies of scale when it comes to the nervous system, digestive tract, internal energy distribution, etc.

Humans are also endothermic, spiders exothermic.

Thank you I was not thinking about brain mass as a percentage of body mass; that is of course crucial.

In the entertaining & educational tradition of Ray Lopez: In Australia, only the spiders that dwell @ knee level & below are venomous.

Some spiders, eg the Huntsman, are your friend [pest control] :

In true Ray Lopez form, you would have ended with a comment about your teenage girlfriend. Average is over my friend.

I once had a Huntsman interrupt an intimate moment in a car with a girlfriend. Damn thing was on my shoulder. She was very calm about it though.

I don't fuck kids

Go Ray!
LOL +1 a thousand times over.

An interesting and active little spider has moved into my bathroom. I don't think that I'll deliberately disturb it.

Well, I expect to see soon in an sports team logo an athletic spider. We've fixated too long with vulnerable lions, tigers and other mammals than can't even endure humans living along them in Europe. Hornets, wasps and scorpions have taken all the status, it's time to acknowledge spider's resilience and intelligence.

South Australian cricket has named itself after the redback spider for years. (

It's better than being called a crow-eater.

Richmond University's sports teams are already called the Spiders. But it is interesting that there are many more teams called Hornets or Scorpions. Spiders are just creepier, probably because they are so smart.

Didn't see MWarhol's comment below.

What is the weight of spiders that humans swallow in their sleep?

Speaking of the cruelty of spiders, consider the unspeakable cruelty of the spider wasps (e.g. the mud dauber Sceliphron). The wasp paralyzes (but does not kill) its spider prey so that the spider does not spoil as it is slowly consumed by the wasp's larva.

The University of Richmond's sports teams are the Spiders. From Wikipedia:

"Richmond is the only university in the United States with the spider as its official nickname."

And in the 20 years I've lived here this is only the second time I've seen so many wasps hunting them. I spent half an hour this past weekend watching and recording it all in the backyard and thinking "nuke the wasps and get overrun by spiders or run the risk of getting stung 14 at once like the last time this happened?"

Kill them all. God will know his own.

Well my comment from earlier disappeared. To repeat: the importance of this post is that spiders can eat all of humanity in a year.

And vice versa!

This is not just a fact about spiders, but a fact about humans as well: apparently this part of our ecological footprint is not that large or unusual.

Once again, we have the conceit that we must do way more "damage" than other animals because ... well ... um ... just because.

For anyone who hasn't seen it, the Ricky and Morty episode "The Ricks Must be Crazy" (Season 2, Episode 6) addresses one potential upshot of our failure to address the spider menace.

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