15 Things You Might Not Know About Rhinos

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iStock.com/johan63

The rhinoceros is the second largest land mammal on Earth, next to the elephant. It's also one of the most aggressive. But despite its reputation as the bully on the playground, rhinos are vulnerable when it comes to one great danger: humans. Their ranks have drastically dwindled over the past century due to poaching and habitat loss, and conservationists are now trying to save them from extinction. In recognition of Save the Rhinos Day on May 1, here are 15 important facts about nature's knight in armor.

1. They're Greek—at least in name.

Rhinoceros in a field with a pond
iStock.com/davidevison

The word rhinoceros stems from the Greek words rhino (nose) and keras (horn). So when you shorten the word to "rhino," you're really just saying "nose."

2. A group of rhinos is called a "crash."

Three rhinos drinking water
iStock.com/Theo_Theron

Crash of Rhinos also happens to be an emo band from Derby, England.

3. They used to be 16 feet tall.

older rhino walking with two younger rhinos
iStock.com/CoreyFord

The paraceratherium, a hornless species of ancient rhinoceros that roamed the Earth 30 million years ago, stood over 16 feet tall. Modern rhinos are significantly smaller, of course, but scientists don't really know how they evolved. The white rhino, which grows up to 6 feet tall, is the largest of the five species that exist today. Measuring under 5 feet in height, the smallest is the Sumatran rhino, which is the only hairy species as well as the closest living relative of the extinct woolly rhinoceros.

4. White rhinos and black rhinos are actually the same color.

two rhinos standing in grass
iStock.com/fishcat007

They're both essentially grayish-brown. One widely spread rumor suggests that white rhinos were originally called wijd (wide) by Dutch settlers in Africa, referring to the animal's wide mouth, which was then mistranslated into English as "white." However, rhino expert Kees Rookmaaker has stated that there is no linguistic evidence to support that tale. It remains a mystery how the white rhino got its name.

5. Rhinos say mmwonk when they're happy.

Indian rhinos are known to make at least 10 distinct sounds, including honks (used during head-to-head fights), bleats (signaling submission), and moo-grunts (used between mothers and calves). Black rhinos use grunts as a greeting and make a mmwonk sound when they're content.

6. They have a complicated relationship with the oxpecker bird.

Oxpecker bird sits on the head of a rhino
iStock.com/Wolfgang_Steiner

Rhinos are often seen with oxpeckers hitching a ride on their backs, but the benefit of these birds is currently debated. The traditional argument is that they snack on bugs and ticks that crawl on the rhino's skin, but in 2000, research on cattle failed to find a consistent benefit to having oxpeckers, while a 2004 study on captive (and tick-free) rhinos found that rather than being helpful, oxpeckers spent much of their time picking at wounds and feasting on the rhino’s blood [PDF]. Meanwhile, other researchers argue that the birds actually do eat ticks and the like. The birds may give the rhinos one additional benefit though: A 2010 experiment found that without oxpeckers, black rhinos were able to detect a person walking up to a rhino 23 percent of the time. With the oxpeckers present that shot up to 97 percent, perhaps explaining why in Swahili, the oxpecker is referred to as the "rhino's guard."

7. They're long-distance sprayers.

rhino spray urinating
iStock.com/Marti Malet

In a show of dominance, alpha male Indian rhinos can spray urine a distance of over 16 feet. This is typically done in the presence of other males or breeding-age females. Other rhinos also spray urine: For males this is typically for marking territory, while female Sumatran rhinos [PDF] have been observed spray urinating 69 times in a 12 hour period before giving birth, and continued this behavior even after the calf was weaned, likely to mask the scent of the calf.

8. They communicate through poop.

rhino sniffing poop
iStock.com/krichie

White rhino droppings are unique identifiers, meaning that a rhino can take one whiff of a dung heap and instantly know the animal's age, sex, and reproductive status, according to one study. All white rhinos in a particular area head to the same spot to defecate, called a midden, which is essentially a communal dumping ground.

"We think of dung as just a waste product, but it's really a good way for animals to communicate," Courtney Marneweck, the head of the study, told National Geographic. "There's a lot of information there that we haven't taken advantage of."

9. Their farts smell like sulfur.

rhino sniffing another rhino's butt
iStock.com/1Photodiva

Rhinos are notorious for passing particularly noxious gas, according to the book Does It Fart? The Definitive Field Guide to Animal Flatulence:

"Rhino farts also smell really bad, so much so that they have even given rise to a piece of brewing terminology; when the yeast used to make alcohol through fermentation produces hydrogen sulfide it gives off a horrible sulfur smell, known as a rhino fart."

10. The males can get aggressive.

two male rhinos fighting with their horns
iStock.com/TonyBaggett

Rhinos aren't afraid to use their horns when it comes to matters of the heart. Male black rhinos are particularly aggressive in their pursuit of a mate, and the rate of "mortal combat" among these horned lovers is higher than any other mammal on the planet. About half of males and 30 percent of females die from injuries sustained while fighting.

11. They're related to zebras.

rhinos gathering with zebras
iStock.com/1001slide

The closest living relatives to rhinos are not elephants or hippos, but rather horses, tapirs, and zebras, all of which are classified as odd-toed ungulates. Rhinos and tapirs walk on three toes, while horses walk on one (which we know as a hoof).

12. They have sensitive feet.

rhino's feet
iStock.com/Kantapatp

Speaking of toes, rhinos do have one weak spot. Rhinos typically put most of their weight on their toenails when they walk to avoid wearing out their sensitive feet. This is easy to do in the wild, where marshes and mushy wetlands abound, but when they're brought to zoos, their toenails tend to wear down on hard surfaces like concrete and asphalt. This can lead to swollen, sore, and cracked feet, making them more susceptible to infection. To tackle this issue, one zoo glued modified horseshoes onto a rhino's toes, which you can read about in the book The Rhino With Glue-On Shoes.

13. They're wallowers.

But not because they're depressed. For a rhino, a nice mud bath is like a day at the spa. It not only helps the animals cool down in hot weather, but it's also great for their skin, helping to ward off pesky insects. Although the animals have a pretty thick dermis, they're surprisingly vulnerable when it comes to bug bites and sunburn.

14. Their horns are made of the same protein found in human fingernails.

close-up on a rhino's horns
iStock.com/alaincouillaud

Rhino horns are made up of nothing but keratin, but that doesn't stop poachers from killing thousands of the animals each year and selling their horns on the black market. The horns are fashioned into jewelry and figurines, and in some parts of Asia they're believed to hold healing properties (they don't).

15. They risk extinction.

man with binoculars in the wild
iStock.com/Peopleimages

Just a century ago, there were more than half a million rhinos around the world. Now, around 30,000 survive in the wild, largely due to poaching. All five species of rhino are in danger, but three are considered critically endangered: Sumatran, Javan, and black rhinos. Today, there are about 60 remaining Javan rhinos, fewer than 100 Sumatran rhinos, and about 5500 black rhinos.

There is some good news, though. Thanks to conservation efforts, black and white rhino numbers have increased in recent years, with the white rhino having been "brought back from the brink of extinction," according to the World Wildlife Fund. The organization Save the Rhinos is taking a multi-pronged approach to the issue, working to deploy more field rangers to protect the animals, reduce demand in Asia, and breed rhinos that are currently in captivity.

This story was republished in 2019.

Plano, Texas Is Home to a Dog-Friendly Movie Theater That Serves Bottomless Wine or Whiskey

K9 Cinemas
K9 Cinemas

For dog owners in Plano, Texas, movie night with Fido no longer just means cuddling on the couch and browsing Netflix. The recently opened K9 Cinemas invites moviegoers—both human and canine—to watch classic films on the big screen. And the best part for the human members of this couple? Your $15 ticket includes bottomless wine or whiskey (or soft drinks if you're under 21).

The theater operates as a pop-up (or perhaps pup-up?) in a private event space near Custer Road and 15th Street in Plano. Snacks—both the pet and people kind—are available for $2 apiece. Dogs are limited to two per person, and just 25 human seats are sold per showing to leave room for the furry guests.

Pet owners are asked follow a few rules in order to take advantage of what the theater has to offer. Dogs must be up-to-date on all their shots, and owners can submit veterinary records online or bring a hard copy to the theater to verify their pooch's health status. Once inside, owners are responsible for taking their dog out for potty breaks and cleaning up after any accidents that happen (thankfully the floors are concrete and easy to wipe down).

While many of the movies shown are canine-themed—a recent screening of A Dog's Journey included branded bandanas with every ticket purchase—they also hold special events, like a Game of Thrones finale watch party (no word on how the puppers in attendance responded to Jon Snow finally acknowledging what a good boy Ghost is).

13 Fascinating Facts About Bees

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iStock.com/florintt

Sure, you know that bees pollinate our crops and give us honey. But there's so much more to these buzzing insects than that.

1. Bee stings have some benefits.

A toxin in bee venom called melittin may prevent HIV. Melittin can kill HIV by poking holes into the virus's protective envelope. (Meanwhile, when melittin hitches a ride on certain nanoparticles, it will just bounce off normal cells and leave them unharmed.) Scientists at Washington University in St. Louis hope the toxin can be used in preventative gels.

Bee stings may also ease pain caused by rheumatoid arthritis. Researchers at the University of Sao Paulo found that molecules in bee venom increase your body's level of glucocorticoid, an anti-inflammatory hormone.

2. Bees work harder than you do.

During chillier seasons, worker bees can live for nine months. But in the summer, they rarely last longer than six weeks—they literally work themselves to death.

3. When bees change jobs, they change their brain chemistry.

bees flying to a hive
iStock/bo1982

Bees are hardwired to do certain jobs. Scout bees, which search for new sources of food, are wired for adventure. Soldier bees, discovered in 2012, work as security guards their whole life. One percent of all middle-aged bees become undertakers—a genetic brain pattern compels them to remove dead bees from the hive. But most amazingly, regular honeybees—which perform multiple jobs in their lifetime—will change their brain chemistry before taking up a new gig.

4. Their brains defy time.

When aging bees do jobs usually reserved for younger members, their brain stops aging. In fact, their brain ages in reverse. (Imagine if riding a tricycle didn't just make you feel young—it actually made your brain tick like a younger person's.) Scientists at Arizona State University believe the discovery can help us slow the onset of dementia.

5. Bees are changing medicine.

To reinforce their hives, bees use a resin from poplar and evergreen trees called propolis. It's basically beehive glue. Although bees use it as caulk, humans use it to fight off bacteria, viruses, and fungi. Research shows that propolis taken from a beehive may relieve cold sores, canker sores, herpes, sore throat, cavities, and even eczema.

6. Bees can recognize human faces.

Honeybees make out faces the same way we do. They take parts—like eyebrows, lips, and ears—and cobble them together to make out the whole face. It’s called "configural processing," and it might help computer scientists improve face recognition technology, The New York Times reports.

7. Bees have personalities

Even in beehives, there are workers and shirkers. Researchers at the University of Illinois found that not all bees are interchangeable drones. Some bees are thrill-seekers. Others are a bit more timid. A 2011 study even found that agitated honeybees can be pessimistic, showing that, to some extent, bees might have feelings.

8. They get buzzed from caffeine and cocaine.

bumblebee on a flower
iStock/Whiteway

Nature didn't intend for caffeine to be relegated to your morning pot of coffee. It's actually a plant defense chemical that shoos harmful insects away and lures pollinators in. Scientists at Newcastle University found that nectar laced with caffeine helps bees remember where the flower is, increasing the chances of a return visit.

While caffeine makes bees work better, cocaine turns them into big fat liars. Bees "dance" to communicate—a way of giving fellow bees directions to good food. But high honeybees exaggerate their moves and overemphasize the food's quality. They even exhibit withdrawal symptoms, helping scientists understand the nuances of addiction.

9. Bees have Viking-like navigation techniques.

Bees use the Sun as a compass. But when it's cloudy, there's a backup—they navigate by polarized light, using special photoreceptors to find the Sun's place in the sky. The Vikings may have used a similar system: On sunny days, they navigated with sundials, but on cloudy days, sunstones—chunks of calcite that act like a Polaroid filter—helped them stay on course.

10. Bees can solve hairy mathematical problems.

Pretend it's the weekend, and it's time to do errands. You have to visit six stores and they're all at six separate locations. What's the shortest distance you can travel while visiting all six? Mathematicians call this the "traveling salesman problem," and it can even stump some computers. But for bumblebees, it's a snap. Researchers at Royal Holloway University in London found that bumblebees fly the shortest route possible between flowers. So far, they're the only animals known to solve the problem.

11. Bees are nature's most economical builders.

In 36 BCE, Marcus Terentius Varro argued that honeycombs were the most practical structures around. Centuries later, Greek mathematician Pappus solidified the "honeycomb conjecture" by making the same claim. Almost 2000 years later, American mathematician Thomas Hales wrote a mathematical proof showing that, of all the possible structures, honeycombs use the least amount of wax. And not only are honeycombs the most efficient structures in nature—the walls meet at a precise 120-degree angle, a perfect hexagon.

12. Bees can help us catch serial killers.

Serial killers behave like bees. They commit their crimes close to home, but far enough away that the neighbors don't get suspicious. Similarly, bees collect pollen near their hive, but far enough that predators can't find the hive. To understand how this "buffer zone" works, scientists studied bee behavior and wrote up a few algorithms. Their findings improved computer models police use to find felons.

13. Bees are job creators.

beekeeper working with bees
iStock/Milan_Jovic

The average American consumes roughly 1.51 pounds of honey each year. On top of that, the U.S. Department of Agriculture estimates that honeybees pollinate up to 80 percent of the country's insect crops—meaning bees pollinate over $15 billion worth of crops each year.

This article was updated and republished in 2019.

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