The zoo whose animals produce sparkly poop, and why.
It’s said that unicorn poop is rainbow-colored, although of course nobody has ever set eyes on an authentic sample from one of these highly elusive creatures.
Certainly here at uBiome, we’ve certainly never been given a unicorn poop sample to process.
What’s less rare, however, is the rather odd practice of deliberately creating a situation where animal droppings are turned a specific color. Or even made glittery.
Read on, all will be revealed.
We begin at the Saint Louis Zoo in Missouri, which runs a sophisticated endocrinology lab.
Now, endocrinology is the study of hormones, hormones being internal chemical messengers that regulate physiology and behavior.
At the St Louis Zoo, researchers determine hormone levels by what one might label, uh, diving into dung.
You see, each year more than 6,000 animal poop samples are gathered up around the zoo, to be processed by the endocrinology lab, whose research is regarded as a great and non-intrusive way to assess hormone levels.
By testing feces, rather than saliva, blood, hair, or urine, they avoid procedures that might put animals under unnecessary stress, or even require anesthesia.
So what kinds of animals does the lab investigate, and what does it look for in poop?
Well, in terms of species, you name it, and the zoo has probably probed its poop.
Some of the most common are giraffes, lions, tigers, and zebras. Some of the less common have included pygmy hippos, tree kangaroos, and wombats.
Fascinatingly, a veterinary endocrinologist can tell a great deal from an animal’s poop.
By monitoring hormone levels and sex steroids such as estrogen and testosterone, for example, it’s possible to determine if a female is pregnant, or having healthy reproductive cycles – or if a male has reached puberty.
Just imagine the advantages of detecting a lioness’s pregnancy by testing her droppings.
Getting a lioness to pee on a stick?
Frankly, it ain’t gonna happen.
But what about that concept of colored poop?
How does this factor into the equation?
Well, if you have an enclosure that houses several animals, nearly always the case in zoos, you need a way to know whose poop is who’s.
After all, we’re told that one piece of zebra dung looks, well, remarkably like another.
Smart zookeepers have therefore found a way to “tag” individual creatures’ poop by placing additives into a particular animal’s food, and colored glitter is a favorite at the Saint Louis Zoo.
Non-toxic plastic glitter is safe for animals to eat, and after passing intact through the gut, it ends up sparkling in a creature’s dung.
Other additives include small plastic beads placed in the meat balls consumed by carnivores, or food coloring injected into fruit or fish before they’re fed to animals.
Fish dyed in this way have proved very useful as food for penguins, for example, when researchers wanted to learn whether they were getting stressed as a result of behind-the-scenes guest tours at the zoo.
You see another biomarker that can be picked up from poop is cortisol, often regarded as the “stress hormone.”
So, how new is color coding animal poop?
Well, not that new, actually.
Back in 2002, Dr. Brenda Griffin, an adjunct associate professor at the University of Florida’s College of Veterinary Medicine, published a fascinating piece of in-depth research describing her work to individualize the poop produced by a clowder of cats, sharing one litter tray in a laboratory.
Reporting on this is almost worth it just to use the word “clowder,” the collective noun for a group of cats. Now we know.
Dr. Griffin experimented with glitter, and also with a concentrated food coloring known as bakers’ pastes, used in professional baking, and far more potent than the food colorings found in grocery stores.
One challenge reported by Dr. Griffin in her paper, is that bakers’ pastes have an incredibly bitter taste, so she needed to experiment with various ingredients to produce food that would tempt the cats while also masking this unpleasant taste.
You’ll no doubt be intrigued to learn that Dr. G and her colleagues did indeed eat their own cat food, depending on their human sense of taste to work out which recipes were most palatable.
Although there were some odd color changes (blue bakers’ paste sometimes produced black or green poop) the result of the research was a firmly-established color palette consisting of black, white, pink, violet, red, and – in a nod to interior design sensibilities – teal, and seafoam green.
Finally, although this research was squarely aimed at doodie differentiation in a laboratory setting, we loved that Dr. Griffin ended her entirely sober scientific paper with the suggestion that her techniques might also have value in more domestic settings.
“In addition,” she concluded, “this methodology has clinical application in identifying the offender in a multi-cat household when elimination problems are present.”
We’re watching you, seafoam-green-pooping kitty.