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A new study investigating how quickly animals urinate, found that no matter how large or small, most mammals urinate in the same time span. 

The study considered 32 animals and found that even though elephant's bladder is 3,600 times larger than a cat's, both animals relieve themselves in about 20 seconds. They also concluded that all animals weighing 3 kilograms or more urinate in the that same time span. 

"It's possible because larger animals have longer urethras," said David Hu, the Georgia Tech assistant professor who led the study, in the press release. "The weight of the fluid in the urethra is pushing the fluid out. And because the urethra is long, flow rate is increased."

"If its urethra were shorter, the elephant would urinate for a longer time and be more susceptible to predators," Hu explained.

The new study is contrasting with another study that indicated urinary flow is controlled on bladder pressure generated by muscular contraction. 

"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, according to the press release. "Mice and rats go in less than two seconds. Bats are done in a fraction of a second."

The more researchers observed the more they realized that 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."

The study has been published in the Proceedings of the National Academy of Sciences (PNAS).