
Arachnids eat as much animal food as all humans - mhb
http://www.economist.com/news/science-and-technology/21718858-arachnids-eat-much-animal-food-all-humans-earth-ecological
======
danaliv
When I was little my dad would always treat spiders with care and respect. I'm
glad he did, because now as a grown-up I find them sort of adorable. Don't get
me wrong, I don't want them in my bed, but when I see one at home my first
instinct is to protect it from my cat. :) They're good to have around—they eat
the bad bugs!

~~~
hellbanner
Maybe he learned about
[https://en.wikipedia.org/wiki/Portia_(genus)](https://en.wikipedia.org/wiki/Portia_\(genus\))
, which are known to hunt "intelligently" (They plot their route instead of
acting only by reaction)

~~~
anotherevan
Oh man, I just finished reading Children of Time[1] which involves sentient
spiders. One of the main characters was named Portia.

[1] [https://www.goodreads.com/book/show/29776274-children-of-
tim...](https://www.goodreads.com/book/show/29776274-children-of-time)

~~~
ccozan
thank you so much! I've read this book some while ago, I wanted to re-read it,
but I forgot the name and couldn't remember it at all!

OT: is there a place in internet where you can describe a book and someone
maybe tells you the name author?

~~~
ErrantX
If it's Sci-Fi or Fantasy, StackExchange generally works:
[http://scifi.stackexchange.com/](http://scifi.stackexchange.com/)

------
Groxx
> _... arachnids consume between 400m and 800m tonnes of animal prey every
> year. ...

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

I'm unreasonably amused that the (sub)title "Arachnids eat as much animal food
as all humans" can be read with multiple interpretations.

~~~
ajuc
I interpreted it the other way initially, it seemed more natural (but I'm not
native English speaker maybe that's why).

------
awinter-py
And some small spiders have 80% of their body cavity taken up by the brain &
nervous system.

More evidence the world is just a giant datacenter.

~~~
wyldfire
> the world is just a giant datacenter.

The mice paid Magrathea for Earth in order to help work out the Ultimate
Question. I'm pretty sure it's something like "what is six times seven?"

~~~
jnicholasp
Have you considered, "How many roads must a man walk down?"?

Seriously, though, it's not unthinkable to me that the simulation argument is
right, and that one of the reasons why simulations might be created is to
explore questions that the parent civilization is curious about and needs
minds of a certain character or experiential background to examine.

We're basically doing that right now, after all, with things like AlphaGo
being created to 'understand' the game of Go at a level we don't. At some
point, the quotes around 'understand' will not be apt, and AlphaGo++ will be
able to put its understanding into terms that will be useful to us.

~~~
mmjaa
Its "whats God's phone number?" you filthy casual ..

~~~
jnicholasp
I don't recall that being in the books, though maybe it was in the movie or
radio show or something.

But "How many roads must a man walk down?" is the 'Question' that the pan-
dimensional mice who commissioned the Earth decided to run with to save their
careers and possibly lives, after the Earth was destroyed 5 minutes before
outputting the final result of its multi-million year computation to determine
what the actual Question of life, the universe, and everything, was.

In short: come at me, noob ;-)

~~~
mmjaa
>>"You just let the machines get on with the adding up," warned Majikthise,
"and we'll take care of the eternal verities thank you very much. You want to
check your legal position you do mate. Under law the Quest for Ultimate Truth
is quite clearly the inalienable prerogative of your working thinkers. Any
bloody machine goes and actually finds it and we're straight out of a job
aren't we? I mean what's the use of our sitting up half the night arguing that
there may or may not be a God if this machine only goes and gives us his
bleeding phone number the next morning?"

------
RangerScience
Hey wait - if whales are also in this category (eating kind of a lot of animal
mass), but have a relatively low population (compared to humans and
spiders)... what kind of ecological impact does a feeding whale have? (Or,
really, the lack thereof)

~~~
delhanty
Surely it means that humans and (baleen) whales will increasingly be
competitors for food such as krill?

[https://risweb.st-
andrews.ac.uk/portal/en/researchoutput/bio...](https://risweb.st-
andrews.ac.uk/portal/en/researchoutput/biomass-and-energy-transfer-to-baleen-
whales-in-the-south-atlantic-sector-of-the-southern-
ocean\(c1a55335-dc3d-4ba4-8984-19125d6e7511\).html)

> Abstract ... Although this only represents 4–6% of the estimated krill
> biomass in the region (and probably less than this percentage of the total
> annual krill production), the depleted numbers of baleen whales resulting
> from past or current whaling activities should be taken into account when
> setting quotas for the commercial exploitation of krill if there is to be a
> recovery to pre-exploitation biomass levels of baleen whales.

------
flippyhead
Slightly off topic but I always wondered why at least some spiders never
developed wings/flight. They do so much other crazy stuff!

~~~
twic
Oh god what if centipedes developed flight. A dozen sets of wings all down the
body. Aaargh.

~~~
steffan
Any Latin speakers? Centiala? Centialae?

~~~
nandemo
Centiptero sounds better. Ptero as in pterodactylus.

(Yes, it's mixed Latin-Greek, but so are _metadata_ , _hypervisor_ and
_hexadecimal_.)

------
psherman
> Each of these consumes, on an annual basis, in the region of 400m tonnes of
> other animals.

The amount of food consumed by spiders is certainly impressive, but limiting
the comparison to the tonnage of animals consumed must just be for clickbait.

While a cursory search failed to find total food consumption, this NPR article
[0] uses USDA data to outline average American food consumption. While these
numbers are obviously inflated compared to average human food consumption
worldwide, the percentage breakdown can shine some more light on the issue.

* Dairy - 630 lbs (32.7%)

* Meat - 185 lbs (9.6%)

* Grain - 197 lbs (10.2%)

* Fruit - 273 lbs (14.2%)

* Vegetables - 415 lbs (21.5%)

* Sugars - 141 lbs (7.3%)

* Fats - 85 lbs (4.4%)

(There was a missing 70 lbs from their provided total of 1996 lbs, so I just
summed the included values)

Even if "of other animals" included dairy products, that is only 42.3% of food
consumption. Pretending we could accurately extrapolate those numbers
worldwide, that would lead to a real total food consumption of ~950 million
tonnes. If "tonnes of other animals" is exclusively meat, that would mean
total human food consumption is more in the ballpark of ~4.2 billion tonnes.

[0]
[http://www.npr.org/sections/thesalt/2011/12/31/144478009/the...](http://www.npr.org/sections/thesalt/2011/12/31/144478009/the-
average-american-ate-literally-a-ton-this-year)

~~~
pvg
_must just be for clickbait._

Why exactly is that clickbait? It's not suggesting spiders are cattle rustling
or too lazy to farm.

~~~
tzakrajs
It's suggesting that arachnids eating as much animal food is even an important
statistic to care about. I think that is the bait.

Edit: I don't know if I know what click bait means.

~~~
vacri
> _I don 't know if I know what click bait means._

Clickbait is over-sensationalising a title to bring more traffic to the
article page, where ads and other monetising things can be served.

HN has been going bonkers over complaining about clickbait titles recently...
it seems our denizens have somehow developed a highly-tuned sense of what
clickbait looks like... but for some reason still can't resist clicking on it
when they see it.

~~~
konceptz
I don't think this is recent but I'm glad people do it. If I read a title that
seem shocking, I'm more likely to see that's it's true or have one of the
first comments call it out upon quick glance.

------
averagewall
The title comparison is entirely meaningless. They arbitrarily chose a 1 year
period. If they chose 1 month, they wouldn't be eating as much. If they chose
100 years, plenty of other animals would do the same. For any carnivore, you
can make the same claim by choosing a suitable time period.

~~~
trattsvamp
I think you misinterpreted the title and probably didn't even read the
article? The spiders each as much animal food as humans regardless of time
period.

> 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.

------
emilong
Looks like the actual article only mentions spiders rather than all arachnids,
but I wonder what the total would be if they tallied mites' consumption as
well?

------
pebblexe
I've always thought that without spiders vertebrates would never have had a
chance to become dominant.

~~~
pavel_lishin
How come?

~~~
civilian
Assumedly because we'd all be drowning in ants and flies.

However, there would have been _some_ animal that came along to fill the niche
that spiders/arachnids do. There's plenty of insects that prey on other
insects. (Here's a quick listicle:
[http://listverse.com/2010/08/09/10-formidable-predatory-
inse...](http://listverse.com/2010/08/09/10-formidable-predatory-insects/) )

~~~
dmix
The "Robber Fly" is easily the most interesting of the predatory flies:
[https://www.wikiwand.com/en/Asilidae](https://www.wikiwand.com/en/Asilidae)

It's being researched at Cambridge University for applications for drones and
other flying robots:
[https://www.youtube.com/watch?v=ukiTGsvFP1Y](https://www.youtube.com/watch?v=ukiTGsvFP1Y)

They also have these large unique round compound eyes, unlike other flies
which are typically flatter. They are very high resolution for such a small
fly and have hundreds of mini lenses. Another longer video explaining the
research into it's vision and hunting behaviour:
[https://www.youtube.com/watch?v=6X8UunUY6U8](https://www.youtube.com/watch?v=6X8UunUY6U8)

They catch the insects in mid-flight, instead of waiting until they land. They
have this amazing ability to fly extremely fast then stopping to turn
midflight to land properly on the fly.

> The fly attacks its prey by stabbing it with its short, strong proboscis
> injecting the victim with saliva containing neurotoxic and proteolytic
> enzymes which very rapidly paralyze the victim and soon digest the insides;
> the fly then sucks the liquefied material through the proboscis.

They also can kill other top insect predators that are far larger and more
powerful with no problem:

> various Asilidae prey on formidable species including stinging Hymenoptera,
> powerful grasshoppers, dragonflies and even other Asilidae, in fact
> practically anything of a suitable size.

------
intrasight
I read that last week and of everything I read in that issue, that statement
was the most interesting and memorable. And I thought that humans were the
ultimate consumers!

------
ClassyJacket
Not sure if it's considered acceptable here or not, but I can't view this
article as it's behind a paywall.

~~~
dmix
I can access it free from Canada, otherwise there is the "Web" button below
the article link to bypass paywalls via google. Which makes them acceptable.

It's short anyway, here you go:

> ARACHNOPHOBIA is a common and powerful fear. Spiders sit high in the
> pantheon of species that have an outsized terror-to-danger ratio. But,
> unsettling though they may be, the eight-legged do excel at keeping six-
> limbed pests in check. They prey upon insects in vast quantities, while, for
> the most part, leaving people alone. Indeed, in 1957 William Bristowe, a
> British arachnologist, wondered whether British spiders might kill prey
> equivalent in mass to all of the people then living in Britain.

> In research published this week in the Science of Nature, Martin Nyffeler of
> the University of Basel, in Switzerland, and Klaus Birkhofer of Lund
> University, in Sweden, attempt to put some numbers on spiders’ dining
> habits. Starting with the available data on the mass of spiders found per
> square metre in Earth’s main habitat types—forests, grasslands, fields of
> crops and so on, they calculated the amount of prey required in each habitat
> to support the weight of spiders there, based on spiders’ known food
> requirements per unit of body weight. That done, they extrapolated their
> habitat-based results to the whole planet, in light of what is known about
> the total areas of such habitats.

> 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. Approximately speaking, then, Bristowe was right.
> Arachnophobes, meanwhile, should consider this: without spiders, there would
> be an awful lot more other creepy-crawlies around.

------
ocschwar
Don't tell Jonah Jameson.

------
miguelrochefort
I don't think this is true.

~~~
CydeWeys
It's important to realize that this is consumption per year, not biomass at
any one time. At any given instant, the vast majority of the terrestrial
biomass is made up of humans, our pets, and our livestock (estimates go as
high as 98%). Most of that is cattle. However, it takes awhile to rear a cow,
whereas insect lifetimes can be in the spans of days. So there's much more
turn-over in the insect realm, which is how the accumulated number across the
entire year grows so large, while still being much smaller than the total
human & livestock biomass at any given time.

~~~
dredmorbius
My understanding is that humans + livestock are 98% of terrestrial
_vertebrate_ biomass. I've seen this from both Daniel Dennett and Paul
Chefurka. Hrm, xkcd, now that I think of it.

I've not run across a good number for _invertebrate_ biomass, though your
point of _total annual cycle_ vs. _instantaneous_ is worth considering.

OK, I've just tracked down a Wikipedia page which gives ants + termites
biomass as _less_ than that of humans + cattle combined, roughly 850 GT vs.
750 GT, taking high-range estimates. Beatles are another highly-abundant
insect phyle which might ... tip the scales.

[https://en.m.wikipedia.org/wiki/Biomass_(ecology)](https://en.m.wikipedia.org/wiki/Biomass_\(ecology\))

~~~
CydeWeys
Thanks for the clarification. If invertebrate terrestrial biomass is of
roughly the same order of magnitude as vertebrate terrestrial biomass, then
the linked article starts making a lot more sense.

