- Researchers say 20 seconds is optimum time to avoid predators
- Urethra sized developed to allow any sized animal to empty its bladder in 20 seconds
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Twenty seconds to relief: researchers found animals all take the same amount of time to urinate
Animals all take exactly 20 seconds to urinate, researchers have found.
They studied 32 species – and found each took the same time to relieve themselves, despite the fact an elephant’s bladder is 3,600 times larger than a cat’s (18 liters vs. 5 milliliters).
The researchers say the strange finding could actually be useful – by teaching engineers how nature uses gravity to regulate flows of liquid.
In fact, all animals that weigh more than 3 kilograms (6.6 pounds) urinate in that same time span, the team said.
‘It’s possible because larger animals have longer urethras,†said David Hu, the Georgia Tech assistant professor who led the study.
‘The weight of the fluid in the urethra is pushing the fluid out.
‘And because the urethra is long, flow rate is increased.’
For example, an elephant’s urethra is one meter in length.
The pressure of fluid in it is the same at the bottom of a swimming pool three feet deep.
An elephant urinates four meters per second, or the same volume per second as five showerheads.
‘If its urethra were shorter, the elephant would urinate for a longer time and be more susceptible to predators,’ Hu explained.
The findings conflict with studies that indicate urinary flow is controlled on bladder pressure generated by muscular contraction.
The study has just been published in the Proceedings of the National Academy of Sciences (PNAS).
Hu and graduate student Patricia Yang noticed that gravity allows larger animals to empty their bladders in jets or sheets of urine.Â
Scroll down for video
The Georgia Institute of Technology team recreates the effect using bottles with different sized tubes attached.
HOW THEY DO IT
The key is the length of the urethra.
An elephant’s urethra is one meter in length.
The pressure of fluid in it is the same at the bottom of a swimming pool three feet deep.
An elephant urinates four meters per second, or the same volume per second as five showerheads.
‘If its urethra were shorter, the elephant would urinate for a longer time and be more susceptible topredators,’ the team say.
Gravity’s effect on small animals is minimal.
‘They urinate in small drops because of high viscous and capillary forces. It’s like peeing in space,’ said Yang, who is pursuing her doctoral degree in the George Woodruff School of Mechanical Engineering.
‘Mice and rats go in less than two seconds.
‘Bats are done in a fraction of a second.’
The research team went to a zoo to watch 16 animals relieve themselves, then watched 28 YouTube videos.
They saw cows, horses, dogs and more.
The more they watched, the more they realized their findings could help engineers.
‘It turns out that you don’t need external pressure to get rid of fluids quickly,’ said Hu.
‘Nature has designed a way to use gravity instead of wasting the animal’s energy.’
Hu envisions systems for water tanks, backpacks and fire hoses that can be built for more efficiency.
As an example, he and his students have created a demonstration that empties a teacup, quart and gallon of water in the same duration using varying lengths of connected tubes.
In a second experiment, the team fills three cups with the same amount of water, then watches them empty at differing rates.
The longer the tube, the faster it empties.
‘Nature has shown us that no matter how big the fire truck, water can still come out in the same time as a tiny truck,’ Hu added.
The trick is gravity. Newton would be proud.
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The comments below have not been moderated.
Steven,
Hartlepool, United Kingdom,
moments ago
Well that was a gross read.
Ray,
Sydney,
35 minutes ago
took me 22 seconds, always knew I wasn’t normal.
regiex758,
essington, United Kingdom,
1 hour ago
Somebody was actually paid money to do this study
Kernkrafty,
Winchester, United Kingdom,
1 hour ago
There is a female researches who comes around once in a while to measure my private parts and do some experiment on them. At least that’s what she says. I wonder whether the study will ever get published.
AmberPanda,
West Country, United Kingdom,
1 hour ago
Thanks for showing the containers with urine in them, didn’t know what it looked like.
Pepper Sanchez,
Palo Seco, Costa Rica,
2 hours ago
My wife alone could drag the average time up to 10 minutes.
Nooms,
St Albans, United Kingdom,
2 hours ago
Just timed it, didnt really need to go, 14 seconds to finish 10 seconds to shake
ImdaPrincesse,
Horsens, Denmark,
2 hours ago
I’m going to put an inexpensive stopwatch in our bathroom and ask all my friends family to use it and make note on a whiteboard (yes, I’ll also spend the big bucks on one of those!). Should make for hours of socially rewarding fun!
jazz2012,
llanelli, United Kingdom,
2 hours ago
My Labrador needs a tap so I can turn him off !
IN-A-WORLD-OF-MY-OWN,
TENERIFE. The Last Resort….., Spain,
2 hours ago
ANOTHER RE-CYCLED DM STORY
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