Researchers from the Georgia Institute of Technology in Atlanta found that the average time most mammals take to urinate is 21 seconds long.
David Hu, assistant professor from the Georgia Institute of Technology, gathered video footage of different animals while they emptied their bladders. Hu and his team went to the Atlanta Zoo to film, and also supplemented their data with videos from the Internet. The team additionally collected urine samples from 16 animals when they visited the zoo.
After analyzing their data and watching 28 videos of animals peeing, the team discovered that animals weighing 6.6 pounds or less do not urinate in a continuous stream. These small animals such as bats, rats, and others, pee in a series of drops. Large animals such as gorillas, goats, and big dogs pee in jets and usually spend 21 seconds relieving themselves. The researchers were surprised to find out that an elephant would take as much time to pee as a smaller animal, such as a cat.
"It's like emptying a swimming pool [and] a bathtub in the same time," Hu told LiveScience in an email.
The researchers concluded that the key element explaining variations in pee time was the length of the animals' urethra. As the animal's body size grows bigger, the length of its urethra also becomes longer. Hu explained that all the animals they studied had the same ration of body size to length of urethra.
A longer urethra, combined with the increased effect of gravity, enabled the larger animals to pee as fast as their smaller counterparts.
The team was hoping that their findings could be used by engineers in developing more efficient designs for better reservoirs and water tanks.
"We realized that this phenomenon had no size limit," Hu added. "Animals use it for 5-mL or 18-L bladders, but there is no reason that it could not be extended to larger systems like swimming pools."
Findings of the study were published in the Proceedings of the National Academy of Sciences.