Mosquitos Have Little Trouble Flying in the Rain 186
sciencehabit writes with an interesting article about the (surprisingly not well studied) effects of rain on flying insects. From the article: "When a raindrop hits a mosquito, it's the equivalent of one of us being slammed into by a bus. And yet the bug will survive and keep flying. That's the conclusion of a team of engineers and biologists, which used a combination of real-time video and sophisticated math to demonstrate that the light insect's rugged construction allows the mosquito to shrug off the onslaught of even the largest raindrop. The findings offer little aid in controlling the pest but could help engineers improve the design of tiny flying robots."
Bats, unfortunately, aren't so lucky: "...these furry fliers need about twice as much energy to power through the rain compared with dry conditions."
Impact energy not the same for small objects (Score:4, Interesting)
Re:Impact energy not the same for small objects (Score:5, Interesting)
On Being the Right Size J. B. S. Haldane in 1928
Re:Impact energy not the same for small objects (Score:5, Informative)
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The total force, yes, but unless I'm thinking about the problem wrong, that force is spread out across a surface area that is somewhere on the order of 3 square inches versus about 12.5-15 square feet (by my very crude estimates), so operating under your assumptions, any given part of the horse's anatomy would experience a force that is only about 30-36 times the force
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Re:Impact energy not the same for small objects (Score:5, Informative)
No, your two main assumptions are badly wrong.
(1) The terminal velocities of larger objects is larger, and the effect is significant [wikipedia.org]. The mouse hits the ground at a much lower speed than the horse.
(2) The mouse and horse are not even remotely point particles so you should be considering pressure instead of force. You'd have to divide your 22000 number by the ratio of whatever bits land on the horse at once to the same for the mouse; this would be a fairly large number.
To illustrate very approximately why larger objects have larger terminal velocities, consider two falling spheres of equal density, one of small radius and one of large radius. An object reaches terminal velocity when the energy it gains from gravity is perfectly canceled by the energy it has to give up to move air molecules out of the way. Let's compute each.
Basic physics gives the first line of the following. Constant density and the definition of velocity gives the second, and the formula for the volume of a sphere gives the third.
(energy gained from gravity)
= (gravity constant) * (mass of object) * (distance it fell in a given time)
= (different constants) * (volume of sphere) * (velocity of sphere)
= (different constants) * (cube of radius) * (velocity of sphere)
The other half is more approximate. The first line is pretty much trivial from the setup. The second line is from the formula for the surface area of a sphere and from the basic physics fact that the energy of an object is proportional to the square of its velocity. The rest is algebra.
(energy lost to moving air out of the way)
= (constants) * (amount of air moved per unit time) * (energy imparted to each molecule of air)
= (constants) * [(surface area exposed) * (distance it fell in a given time)] * (velocity of sphere squared)
= (constants) * [(radius squared) * (velocity)] * (velocity squared)
= (constants) * (radius squared) * (velocity cubed)
At terminal velocity, these two are equal. Simple algebra gives the answer from here.
(constants) * (cube of radius) * (terminal velocity) = (constants) * (square of radius) * (cube of terminal velocity)
(constants) * (radius) = (square of terminal velocity)
(terminal velocity) = (constants) * sqrt(radius)
The large sphere has large radius, so large terminal velocity. Incidentally this is the formula from the Wikipedia page I linked, though my assumptions were very, very approximate and are probably different from the ones used to derive it.
Re:Impact energy not the same for small objects (Score:5, Funny)
Okay, there's only one way to settle this once and for all. BRB
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Simplify the experiment.
F=M*A
Given two objects of equal velocity, the more massive imparts more force.
The determining factor in the bounce vs. splash is how much energy is required to destroy the cellular bonds.
Assume both objects are spherical with the same composition and density, and no outside forces such as gravity or air resistence, etc. This also allows us to assume the same amount of force applied to a given surface area upon impact.
If the velocity is low enough, neither object will impact with enou
Re:Impact energy not the same for small objects (Score:5, Funny)
A man, a horse, and a mouse walk into a bar...
"Barkeep," the man says "I need 3 pints of beer and access to your roof."
"Here you are," the barkeep says as he gives him the beer and keys to to roof.
Then he looks at the horse and asks "Why the long face?"
The horse pondered for a moment and then replied
"Well, basic physics gives the first line of the following.
Constant density and the definition of velocity gives the second, and the formula for the volume of a sphere gives the third.
(energy gained from gravity)
= (gravity constant) * (mass of object) * (distance it fell in a given time)
= (different constants) * (volume of sphere) * (velocity of sphere)
= (different constants) * (cube of radius) * (velocity of sphere)
The other half is more approximate. The first line is pretty much trivial from the setup. The second line is from the formula for the surface area of a sphere and from the basic physics fact that the energy of an object is proportional to the square of its velocity. The rest is algebra.
(energy lost to moving air out of the way)
= (constants) * (amount of air moved per unit time) * (energy imparted to each molecule of air)
= (constants) * [(surface area exposed) * (distance it fell in a given time)] * (velocity of sphere squared)
= (constants) * [(radius squared) * (velocity)] * (velocity squared)
= (constants) * (radius squared) * (velocity cubed)
At terminal velocity, these two are equal. Simple algebra gives the answer from here.
(constants) * (cube of radius) * (terminal velocity) = (constants) * (square of radius) * (cube of terminal velocity)
(constants) * (radius) = (square of terminal velocity)
(terminal velocity) = (constants) * sqrt(radius)
The large sphere has large radius, so large terminal velocity. Incidentally this is the formula from the Wikipedia page I linked, though my assumptions were very, very approximate and are probably different from the ones used to derive it.
In summary, this asshole is going to shove me off a roof just to prove a point, physics says they'll both survive, but I'm fucked."
Re:Impact energy not the same for small objects (Score:5, Funny)
Force = dP / dt
P = mass * velocity
A mouse weights around ~20g , a horse around ~450kg. If we assume that both of them have the same velocity when touching the floor, the horse will experience a force that is ~22000 times higher. Easily explains the splashing... ( I could go more and calculate an approximation of the value force itself, but I think this is enough )
Yes. But the real question is: What would happen to a bag filled with 22,500 mice (weighing a total of 450kg)?
Would the mouse-bag make a splash like the horse? Or would each individual mouse walk away with a slight shock?
Re:Impact energy not the same for small objects (Score:5, Interesting)
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Not necessarily true. We are talking about a value well under Avogadro's number. Even if we had enough mice, the inter-particle interactions would be highly non-newtonian. For 22500 mice, I would still model them as solid particles (it can be done, and is not quite as hard as you might think). The effects on individual mice would be quite interesting, in my estimation. Individuals on the leading surface of the bag would be expected to bear the brunt of the impact, while his/her compatriots at the rear
Re:Impact energy not the same for small objects (Score:5, Insightful)
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Re:Impact energy not the same for small objects (Score:4, Funny)
Excellent, so I can toss mice off the top of my building all day long and not have to worry about killing them.
Suck it PETA. Throwing these mice is intrinsic to testing the catacopter.
Re:Impact energy not the same for small objects (Score:5, Insightful)
AIUI, you assume wrong.
I am aware of that, but I didn't want to complicate things, in case the reader was not a physicist. Sometimes simple assumptions can still give you a clear indication of what is going on.
Re:Impact energy not the same for small objects (Score:5, Insightful)
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I wish this was reddit so I could upvote all of zero.kalvin's posts. He deserves a lot more credit in this thread than techno-vampire's minor-nitpick sniping, and I think that would play out in a democratic voting scheme, but here on slashdot the best we can hope for is that the ones with mod points are smart enough to read the entire thread and make sure zero.kalvin gets more karma than techno-vampire.
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Reddit moderation is feel-good, idiotitc group think. Not that Slashdot moderation doesn't have its problems, but it wouldn't be better served by following the reddit model.
Re:Impact energy not the same for small objects (Score:5, Informative)
The simplified answer was actually the next two sentences in the essay:
'You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only to a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force."
You are debating a single sentence of an essay that is an amazing read to say the least. I highly recommend reading it: http://irl.cs.ucla.edu/papers/right-size.html [ucla.edu]
Re:Impact energy not the same for small objects (Score:5, Funny)
The whole point was to show, that the difference between a mouse and horse isn't small, but rather gigantic.
Thank you, sir! This would never have occurred to me if you hadn't brought it up. Now I better understand why my parents would never give me a horse as a child; it wouldn't fit in the cage with the mice, and it would splash if I accidentally dropped it.
Re:Impact energy not the same for small objects (Score:5, Funny)
Give me a break, I wanted to write that comment that was as short, as quick, and as simple as possible.
You didn't even take relativistic affects into account. What if the horse and mouse are being dropped near a large mountain? And what about the possibility of quantum tunneling?
You're just lazy and sloppy, that's all.
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I take it, then, that you don't understand the cube/square law. [wikipedia.org] If you did, you'd understand why a mouse offers more wind resistance and has a lower terminal velocity than a horse. It's not really about physics, it has to do with the way the ratio of volume to area changes as an object scales up.
Ah, so in other words, it's about physics.
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You can call it that if it makes you happy, but it's really a matter of geometry, which is, of course, math.
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His explanation was correct, just not complete. Dynamics becomes quite a bit more complicated when you include air resistance. In this case, unnecessarily complicated. He made a simplification that illustrates the point, gets the right answer, and greatly simplifies the problem. A simplification just like your spherical horse. So stop being pedantic.
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Re:Impact energy not the same for small objects (Score:5, Funny)
What about a spherical horse in a vacuum?
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"In the time of war, the value of sin(x) may reach 2." -- attributed to military department.
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Re:Impact energy not the same for small objects (Score:5, Funny)
AIUI, you assume wrong. The horse's terminal velocity is considerably higer (and considerably more terminal) than that of the mouse.
and thus you strengthen his point. The mouse wins with conservative estimates. The mouse wins by more when you take into account more detailed explanations.
Maybe he should have said "even if you assume..."
This is called the principle of conservation of mice.
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You owe me a new keyboard.
Re:Impact energy not the same for small objects (Score:5, Funny)
But your mouse remains safe, as predicted.
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Ah, so *that's* where all that vacuum comes from - they mine it!
Re:Impact energy not the same for small objects (Score:5, Funny)
Dropping a bus on a horse, a human or mouse at the bottom of a thousand-yard mine shaft will still wreck the bus. Wouldn't be good for the creatures either (probably kill the mosquito too).
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On Being the Right Size J. B. S. Haldane in 1928
Sextus Empiricus could have told us that 1750 years sooner if he had a mouse, a rat, a spare horse and a thousand-yard mine shaft.
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I know a guy who as a child "saved" his guinea pig from an incoming dog by throwing it out the balcony.
It didn't survived.
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On Being the Right Size J. B. S. Haldane in 1928
to be fair, the world has changed since 1928. These days, a man splashes.
Re:Impact energy not the same for small objects (Score:5, Interesting)
Aside: This is only tangentially relevant to TFA, but I hope it gets a pass from the moderators and not modded down as OffTopic:
Preface: Bats are kind of like mice with flappable wings. One would expect that they would have that knack of flying, pretty much instinctively. One would not expect them to thwart Darwin's Law, survival of the fittest, by doing 'stupid' things while flying, but ...
True Story: I was driving home from work one night and was only a block away from home in a residential neighborhood, when something fell out of the sky and loudly hit the hood of my car. I stopped, engine still running and headlights on, to get out and see what had happened. A bat, with it's wings wrapped around something or other, had fallen out of the sky. As I was contemplating retrieving the combo windshield squeegee / ice scraper from the trunk to brush this poor dead creature off my hood, it separated from what it fell from the sky with and flew away. Almost immediately, a second bat roused itself and flew from the hood in presumed pursuit of the first bat. The only thing that I could figure is that those 2 bats were copulating in mid-air, lost control, and plummeted down to earth and landed on my car's hood.
I'm not a biologist, nor have I ever played one on TV, but it would seem that the act of 2 small mammals copulating in mid-air would violate the base instinct of survival that falling out of the sky might negate. Unless ... unless they routinely know that such a fall is non-lethal, and other base instincts kick into play. Kids. You let them out to run around without supervision in the evening after a big supper (of bugs), and the next thing you know, they're getting into trouble. And yes, there was a full moon that night.
Question: (Directed to anyone who might actually know): Was I fortunate to see a common occurrence, something that very few people have an opportunity to see, or were those bats engaged in very risky behavior that they managed to survive?
Inquiring minds want to know, and Bing has so few good answers.
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Were there any overhead power lines nearby? I've seen pairs of birds fall onto the road then get up again a short time later (or a single bird... although normally they don't get up again) after they touch wings when on different wires.
The fact that your bats were wrapped around each other probably means it wasn't an electric shock though... and maybe they were too small to spread across a pair of power line?
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There were power lines at the edge of the road in the easement, but I don't believe that the power lines were a factor.
The coupled bats fell straight down onto the hood of my car. It may have been my imagination, but I could have sworn that I saw them just before they hit the car, seen as a dark blob, which then bounced slightly and remained motionless until they 'revived' as I previously narrated. My headlights were on, I was driving slowly (~20 mph), and there was a full moon & clear night sky.
Of co
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I had a quick look through some journals and this is the closest thing I could find:
Mating Behavior as a Possible Cause of Bat Fatalities at Wind Turbines, Paul M. Cryan, The Journal of Wildlife Management, Vol. 72, No. 3 (Apr., 2008), pp. 845-849, Allen Press
Article Stable URL: http://www.jstor.org/stable/25097617 [jstor.org]
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While I know this isn't what you were answering, but it turns out that lung damage is a major factor in bat deaths near turbines.
http://www.cell.com/current-biology/retrieve/pii/S0960982208007513 [cell.com]
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by doing 'stupid' things while flying, but ...
Humans due stupid stuff while flying too, it's called "the mile high club"... or do you really believe that only passengers join "the club"?
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Re:Impact energy not the same for small objects (Score:4, Informative)
A mouse could fall off a building and walk away. People, not so much. The smaller you are, the more resistant you are to long falls.
Close.... the lower your mass to surface volume density; the more resistance you are to long falls.
The most resistant objects to long falls are very large organisms that have very little mass, and therefore a higher ratio of surface volume to mass.
The larger the object's horizontal cross-section w.r.t the ground, the greater the air resistance, the lower the velocity while falling.
The lower the velocity towards the ground while falling, the lower the change of momentum at the point of impact.
The lower the mass of the object, the lower the change of momentum at the point of impact with the ground.
The lower the change of momentum at the point of impact with the ground, the lower the upward force that is exerted upon the object in the collission.
The difference in damage between the two objects then depends on what the two different objects were constructed from. Different materials have different strengths; a titanium skeleton will probably fair better than something made out of fired clay.
Figures. (Score:5, Funny)
You have to work your ass off to keep the things you like alive/going (plants, cars, house, etc), yet pests like mosquitoes, bankers, and politicians you just can't get rid of no matter how hard you try.
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No he didn't.
Lawyers clearly are not alive, since they possess no soul. They are the undead.
This is new? (Score:2)
I thought anyone who has ever been fishing already knew that?
Fishing in light to medium rain still ends up getting you rather bitten at dusk and dawn during mosquito season.
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Yup. Rain doesn't stop the little buggers at all. To add further insult, it washes off the insect repellent too.
/. editors: Too many games, not enough reality (Score:2)
You know that's not true. A bus is solid, a raindrop is liquid.
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Surface tension is a rather interesting study of fluids.
Re:/. editors: Too many games, not enough reality (Score:5, Interesting)
So, it's more like phasing through the front of an oncoming bus, landing comfortably in one of the seats, then escaping out the rear before the bus plows into a concrete wall.
Re:/. editors: Too many games, not enough reality (Score:5, Funny)
*sigh* I don't understand these bus analogies. Can someone please give me a car analogy instead?
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Just substitute bus by Ford F150 or Hummer, that's all
Re:/. editors: Too many games, not enough reality (Score:5, Funny)
But the bus analogy is still wrong, because the entire point of the article is that the mosquito is not smashed by the raindrop. Instead the mosquito simply merges into and falls with the drop, then escapes before the raindrop hits the ground.
So, it's more like phasing through the front of an oncoming bus, landing comfortably in one of the seats, then escaping out the rear before the bus plows into a concrete wall.
*sigh* I don't understand these bus analogies. Can someone please give me a car analogy instead?
It's like a raindrop that hits a Yugo. The raindrop merges into the Yugo. The Yugo stops because the electricity fails. You get out, a little wet because of the leaking roof, but still OK.
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Well, the mosquito would probably survive (the impact, not the drowning) when the drop it is in hits the ground, too. I often hit when I swat at flies (which are bigger and heavier than mosquitos), and they simply butt into the wall (with, relatively, quite some force), shake their head, curse at me and simply continue buzzing about.
These little things are built like tanks, I tell you.
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Yes, but a mosquito is solid and a human, in this scenario, is liquid.
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Physics doesn't scale by size either. Strength is related in different ways to length and to cross section, which is length (or breadth) squared. Mass is proportional to length (or breadth) cubed. That's not even remotely the same. Dropping a bug a meter is not like dropping an elephant a hundred meters.
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True, the analogy is wrong.
They should calculate how much water that would be , and what the effect would be on human beings.
One thing to take into account is the position of the body and area of impact : I have a feeling that if you put the amount of water on someone head while standing up, it would be harder to withstand than if you were crouched down , and the water is put on your back.
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Why don't they? (Score:2)
Well that leads to the obvious question then, why don't they? They seem to disappear quite quickly when it starts raining.
Re:Why don't they? (Score:5, Funny)
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Because when it's raining, they're off to the puddles to make sweet, sweet love and deposit thousands upon thousands of eggs, I suspect.
Also, I may well be able to survive a good batting with a foam LART, but that doesn't mean I like it.
I for one... (Score:2)
The findings offer little aid in controlling the pest but could help engineers improve the design of tiny flying robots.
I, for one, welcome our new insect overlords.
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Finally we may beat the mosquitoes by fighting them with tiny anti-mosquito UCAVs.
The Wooden Wonder (Score:5, Funny)
Yes, Mosquitos could fly in the rain. However they would have trouble dropping their bombs accurately and obviously the recon version wouldn't get good photos.
The night fighter version would fare better with its radar, if there were any German bombers up there to intercept.
But of course sometimes they had to fly in bad weather, such as just before D-Day.
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Mosquito's secret weapon (Score:3)
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Just after reading the headline i half expected that they were going to say the erratic way they fly provided a bonus against ever hitting a raindrop.
Oh well, sustaining the impact is cool, too.
Here's the video for it ... (Score:4, Informative)
Cheers.
Matter of chance (Score:4, Insightful)
Re:Matter of chance (Score:5, Funny)
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Explain the Pegasus then.
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Now why their body structure is like that is a question that somebody else have to answer.
Because if it weren't like that, the mosquito wouldn't be able to live where it does.
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Tiny Flying Robots? (Score:4, Insightful)
The findings offer little aid in controlling the pest but could help engineers improve the design of tiny flying robots.
Great! Because I was just thinking to myself, "we really need more tiny flying robots. If I have to wait 20 years for the CIA to solve the raindrop problem and weaponize these things, I'll die of boredom before videos of them assassinating people with them show up on YouTube."
Too heavy on the sarcasm? Fortunately I don't say stuff like this out loud.
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The findings offer little aid in controlling the pest but could help engineers improve the design of tiny flying robots.
Great! Because I was just thinking to myself, "we really need more tiny flying robots. If I have to wait 20 years for the CIA to solve the raindrop problem and weaponize these things, I'll die of boredom before videos of them assassinating people with them show up on YouTube."
Too heavy on the sarcasm? Fortunately I don't say stuff like this out loud.
FWIW (not much), it would probably be easy to weaponise actual mosquito's than to try and reproduce them as robots. Make a few billion sterile females, load them up with some form or malaria or plague that can't possibly be transmitted by regular mosquito's, and drop them on the enemy. What could possibly go wrong?[1]
[1] For the humour impaired, that's a rhetorical question. I'm well aware of what could go wrong
Water Spritzer (Score:2)
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Effect of Rain on Mosquito Behaviour (Score:5, Funny)
In Winnipeg, it isn't that mosquitoes can't fly in the rain, they just don't like it very much. Usually, your basic Winnipeg mosquitoes just jack a car and drive to their next victim. If the driver's lucky, the mosquitoes will let him go instead of keeping him for an en route snack. If there's a dog or cat in the car...don't ask. It won't be seen again.
speed of an ant (Score:2)
There are a lot of such phenomena in the wild life world. It is one more reason to protect biodiversity, so that these species do not disappear and could be studied by engineers in the future.
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If a man were the size of an ant, he'd be able to run the same speed. The "feats" of insects aren't due to incredible adaptations, they're due to you extrapolating using the wrong function.
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I listened to a radio show on this topic at http://itc.conversationsnetwork.org/ [conversationsnetwork.org] . It is being studied already, but engineers cannot get it how it works so far. They say this threatened lizard should be definitely preserved for studying by smarter engineers in the future.
Still my claim hold, it was: If a man could cover the same number
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There ARE incredible adaptations out there, it's just that the "if a $YOUR_CHOICE_OF_SMALL_INSECT were the size of a man it could $AMAZING_FEAT_HERE" stuff isn't. It's simply a meaningless linear extrapolation when the proper function is quadratic or cubic (or higher).
Yes, if a man could cover the same number of lengths of his body as an ant in the same amount of time, he might be running 1500 km/h. So? If the Empire State building could cover the same number of lengths of it's height as I can when runni
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Another interesting observation about insects is that the intelligence of their movement is imbedded, hardwired, into the mechanical structure of their body. They think very little by brain when they move with large number of legs.
And ants communicate with smells. They emit molecules which transmit meaning for them. Sometimes they even connect antennas, as if creating one organism from several ones, to discuss faster.
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Mosquito in itself is not dangerous, but parasites which it carries and distributes are (mostly from 00h00 till 04h00). Perhaps, good screens on windows and an UV-electric mosquito cleaner indoors will do?
Terrible analogy (Score:4, Insightful)
When a raindrop hits a mosquito, it's the equivalent of one of us being slammed into by a bus. And yet the bug will survive and keep flying.
In other words, it's definitely not the equivalent being slammed by a bus.
Seen the video (Score:2)
Still can't believe the mosquito survived without its wing being ripped off.
Oh come on... (Score:2)
You mean the summary couldn't give us even a tiny hint about how the mosquito can fly through rain?
If I wanted to go read articles, I'd be reading articles right now instead of being on /. with a mouthful of bagel.
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I feel your pain, brother. This post [slashdot.org] seems to be the most comprehensive, quoting a good bus analogy by someone claiming to have RTFA. ;o)
Old news. (Score:3)
The Hellstrom Chronicle (Score:2)
I'm not sure if this is buried in a comment elsewhere, but I wanted to forego modding to point out an Oscar-winning "documentary" that (sort of) examines this question:
The Hellstrom Chronicle [youtube.com]
This scene is filmed in slow motion demonstrating what happens when water drops hit insects.
Sadly, this title is not available on DVD or Blu-Ray.
I routinely get smashed by giant bodies of water (Score:4, Funny)
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can carry a hundred times their body weight and I can carry thousands of ants.
I wouldn't recommend it. They have a mean bite.
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I see some Troll Science potential here...
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