Do Larger Animals Take Longer to Pee?


A rhinoceros has a bigger bladder than a dog, and generates urine by the bucketful. So which animal spends more time peeing? Scientists from Georgia Tech figured that, in general, larger animals would pee for longer. To test their hypothesis, they set up high-speed cameras to record Zoo Atlanta animals as they “did their business,” and supplemented that footage with videos from YouTube. Altogether, they analyzed the urination of 32 different animals ranging in size from mice to jaguars, gorillas, and elephants. 

Surprisingly, it turned out that mammals which weigh more than 6 pounds urinate for roughly the same length of time, regardless of their size. That is, they pee for 21 seconds on average, give or take 13 seconds. “This invariance is noteworthy,” the scientists write in the study, which was published in Proceedings of the National Academy of Science, “considering that an elephant’s bladder, at 18 liters, is nearly 3600 times larger in volume than a cat’s bladder at five milliliters.”

The reason that an elephant can release the equivalent of nine large soda bottles worth of urine in the same amount of time that it takes a cat to lose a spoonful of urine boils down to flow rates. An elephant pees faster than a cat because its urethra—the tube that delivers urine from the bladder and out of the body—is wider. The elephant’s urethra is also longer, allowing the force of gravity to act more strongly on fluid flowing through it.  

Mice and rats and other animals weighing under 6 pounds don’t fit the 21-second rule, however. That’s because their urinary tracts are so small that they have to battle capillary action, which is the tendency for a fluid’s molecules to stick to themselves and to the walls of a container and flow upwards. The pee is more viscous, and moves so slowly that smaller animals can’t generate a jet of urine. Instead, the urine falls out in tiny droplets.

For the rest of the mammals, it’s not clear why the 21-second rule holds across animals with widely varying sizes. The researchers suggest that it is a matter of physics rather than evolutionary adaptation. 

The scientists say their research could be helpful in diagnosing urinary problems in animals. For instance, if a zookeeper notices a gorilla is peeing for a lot more or a lot less than 21 seconds, it could indicate that something is wrong.   

Oddly enough, this weird area of research could also have implications for infrastructure. From the paper:

[B]y providing a water-tight pipe to direct urine downward, the urethra increases the gravitational force acting on urine and therefore, the rate at which urine is expelled from the body.… Engineers may apply this result to design a system of pipes and reservoirs for which the drainage time does not depend on system size. This concept of a scalable hydrodynamic system may be used in the design of portable reservoirs, such as water towers, water backpacks, and storage tanks. 

Who knows, perhaps this research will pave the way for a “bladder” future. 

This Is the Age When Puppies Reach 'Peak Cuteness'

All puppies are cute, but at some point in a young dog's life, it goes from "It's so cute I could squeeze it to death" to merely regular cute. But when? According to one recent study in the journal Anthrozoös, peak cuteness hits between 6 and 8 weeks old for many dogs, The Washington Post reports.

Finding out when puppies reach their peak attractiveness to humans may give us insights into how domestic dogs evolved. Researchers from the University of Florida asked 51 students at the school to look at 39 black-and-white images of dogs, who belonged to three different breeds and whose ages ranged from birth to 8 months. The viewers then rated them on a sliding scale of squishability.

The results will sound familiar to dog lovers. Puppies aren't entirely adorable immediately after they're born—they can look a little rat-like—and the participants rated them accordingly. As dogs get older, as much as we might love them, their squee-worthy cuteness declines, as the attractiveness scores reflected. The sweet spot, it turns out, is right around when puppies are being weaned, or between 6 and 8 weeks old.

The participants tended to rate dogs as most attractive when the pups were within the first 10 weeks of their lives. According to the results, Cane Corsos were at their cutest around 6.3 weeks old, Jack Russell terriers at 7.7 weeks old, and white shepherds at 8.3 weeks.

The study only used still photos of a few breeds, and it's possible that with a more diverse sample, the time of peak cuteness might vary a bit. Certain puppies might be cuter at an older age, and certain puppies might be cuter when they're even younger. But weaning age happens to coincide with the time when puppies are no longer getting as much support from their mothers, and are thus at a high risk of mortality. By evolving to attract human support at a time when they're most vulnerable, puppies might have boosted their chance at survival until they were old enough to completely take care of themselves.

[h/t The Washington Post]

Martin Wittfooth
The Cat Art Show Is Coming Back to Los Angeles in June
Martin Wittfooth
Martin Wittfooth

After dazzling cat and art lovers alike in 2014 and again in 2016, the Cat Art Show is ready to land in Los Angeles for a third time. The June exhibition, dubbed Cat Art Show 3: The Sequel Returns Again, will feature feline-centric works from such artists as Mark Ryden, Ellen von Unwerth, and Marion Peck.

Like past shows, this one will explore cats through a variety of themes and media. “The enigmatic feline has been a source of artistic inspiration for thousands of years,” the show's creator and curator Susan Michals said in a press release. “One moment they can be a best friend, the next, an antagonist. They are the perfect subject matter, and works of art, all by themselves.”

While some artists have chosen straightforward interpretations of the starring subject, others are using cats as a springboard into topics like gender, politics, and social media. The sculpture, paintings, and photographs on display will be available to purchase, with prices ranging from $300 to $150,000.

Over 9000 visitors are expected to stop into the Think Tank Gallery in Los Angeles during the show's run from June 14 to June 24. Tickets to the show normally cost $5, with a portion of the proceeds benefiting a cat charity, and admission will be free for everyone on Wednesday, June 20. Check out a few of the works below.

Man in Garfield mask holding cat.
Tiffany Sage

Painting of kitten.
Brandi Milne

Art work of cat in tree.
Kathy Taselitz

Painting of white cat.
Rose Freymuth-Frazier

A cat with no eyes.
Rich Hardcastle

Painting of a cat on a stool.
Vanessa Stockard

Sculpture of pink cat.
Scott Hove

Painting of cat.
Yael Hoenig


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