8 Adorable Animals That Are Surprisingly Violent

iStock
iStock

They're cute. They're cuddly. But beware: they're killers.

1. KOALAS

Young koala in a tree.
iStock

It may seem hard to believe, but the world's most cuddly animal has a dark side. Most of the time, these tree-huggers keep to themselves, adhering to a strict schedule of snacking and snoozing (up to 22 hours a day). But sometimes, a koala snaps. Koala-on-koala violence is generally pretty mild, but they have been known to go after dogs and even humans.

For example: In December 2014, Mary Anne Forster of South Australia found herself at the receiving end of a vicious bite after trying to protect her two dogs from an aggressive koala. The koala sank its teeth into Forster's leg and refused to let go, relenting only after she reached into its mouth and pried its jaws apart with her hands. Forster then walked her dogs more than a mile back to her house before going to the hospital for stitches, proving that the only thing tougher than Australian wildlife is an Australian.

2. BEAVERS

Beaver in water looking at camera.
iStock

They've got huge, razor-sharp teeth that never stop growing. They're fiercely territorial. They build complex underwater lodges with architectural precision. And, most importantly, they don't take crap from anybody. There was the fisherman in Belarus who died when a beaver bit through his femoral artery. There was the lake in an Alaskan dog park where angry beavers sent a half-dozen dogs to the emergency vet for stitches, prompting park officials to post signs reading "WARNING AGGRESSIVE BEAVERS ARE LIVING IN UNIVERSITY LAKE!"

And those are just the healthy, well-adjusted ones. Rabid beavers have gone after swimmers in Canada and the U.S., including an 83-year-old woman in Lake Barcroft, Virginia. "There is no way I will swim in that place again," she said after the incident.

3. COWS

Heck cattle and calf.
iStock

Not all cows. But some cows. And those cows are terrifying. They're called Heck cattle, also known—and we are not making this up—as "Nazi Super Cows."

In the 1920s and '30s, German zoologists (and brothers) Heinz and Lutz Heck each sought to recreate the extinct wild ox called the aurochs, which featured heavily in Teutonic mythology. Heinz Heck chose Spanish fighting cattle as a breeding strain for their prehistoric shape and aggression, and the Nazis used their fierce image in propaganda. Then, World War II happened. The Nazis fell, but the uber-cows survived.

Heck cattle still roam Bavaria to this day and are available for purchase by those with a death wish. Farmer and photographer Derek Gow brought a herd of Heck cattle to his UK farm in 2009 and successfully bred them before realizing he was in over his head. "They would try to kill anyone," he told The Guardian of the dozen or so he had to put down because of the danger they posed. "Dealing with that was not a lot of fun at all."

4. DOLPHINS

Dolphin smiling in a pool.
iStock

It sounds outrageous, but it's true: dolphins are actually pretty horrible.

Researchers have suspected as much since the 1990s, when the battered corpses of hundreds of porpoises and baby dolphins started washing up on both sides of the Atlantic. Eventually the researchers concluded that male dolphins were slaughtering other dolphins, including their own babies, just because they could [PDF].

This news was especially alarming to federal officials, who were concerned about human safety in the growing and unregulated industry of dolphin tourism. "It's a time bomb waiting to go off," said a spokeswoman for the National Marine Fisheries Service.

If that wasn't bad enough, dolphins have sexually assaulted divers and swimmers on numerous occasions, and have been known to play volleyball with helpless baby sharks.

5. PRAIRIE DOGS

Prairie dog eating in a field.
iStock

Move over, dolphins: you’ve got competition for Most Horrifying Murder Spree. And prairie dogs, as it turns out, do not take kindly to competition. Researchers say white-tailed prairie dogs routinely hunt and slaughter ground squirrels, with which they compete for resources.

The prairie dogs are plant-eaters, so once they've bitten the squirrels to death, they just drop the carcasses and stroll away. The first time prairie dog expert John Hoogland saw it happen, he was shocked. "It boggles the imagination that something like that was going on under our noses and we didn't notice," he told New Scientist (which—be warned—includes Hoogland's gruesome images of the carnage in its story).

Unlike the murder-happy dolphins, however, the prairie dogs have a clear motivation. Prairie dog serial killers (that is, those that just kept killing) tend to have more babies than non-killers, and they and their offspring are more likely to survive.

"It begs the question of whether it's going on in other species," Hoogland said.

6. SLOW LORISES

Slow loris hiding behind a tree.
iStock

After the dolphin, the slow loris looks like a saint. A shy, weird saint, with a mouth full of needle-like teeth and venomous elbows.

Yes, the slow loris has venomous elbows. When a loris feels threatened, it throws its arms over its head. This is adorable, but it's also strategic, giving the little primate an opportunity to lick the toxin-producing glands in its upper arms and fill its mouth with venom. While the venom itself is only strong enough to kill smaller animals, loris bites have sent humans—including one researcher—to the hospital in anaphylactic shock.

Some scientists argue that the loris's elbow grease isn't venom at all, and that its ability to kill is purely incidental. But … this is probably not much comfort to someone who's just been bitten.

7. SWANS

A swan swimming in green waters.
iStock

Like most cows, most swans are fine. Sure, they get a bit territorial during breeding season, but who doesn't? But the swans that are not fine are really, really not fine.

Take Hannibal, the swan who killed 15 other swans and injured dozens more on the grounds of Pembroke Castle in Wales. Hannibal bit his victims, beat them with his wings, broke their toes, and held their heads underwater until they drowned. After each brutal attack, Hannibal would parade in front of his kill, displaying the carnage for his wife—Mrs. Hannibal—and cygnet.

And then there's Mr. Asbo, the swan that terrorized rowers on the River Cam in Cambridge for years. Mr. Asbo (short for "Anti-Social Behaviour Orders") regularly attacked and even capsized small boats before turning his aggression on larger vessels. Eventually, even the Royal Society for the Prevention of Cruelty to Animals (RSPCA) agreed that Mr. Asbo was "out of control" and got a license to relocate him and his mate to another county. One year later, a young male swan appeared in the same spot and started threatening people. Locals named the cocky newcomer Asboy, after his father.

8. HIPPOPOTAMUSES

Hippopotamus standing in the water.
iStock

Each year, the humble hippopotamus kills more people than lions, tigers, or bears. Or sharks, for that matter. (In the hippo's defense, humans kill quite a lot of hippopotamuses. This is not cool.) They're intensely aggressive, which is a dangerous quality in an animal that can reach 17 feet long and 10,000 pounds. They're not slow, either: They can reach speeds of up to 30 miles per hour on land, outpacing even Olympian Usain Bolt. They go after each other, after humans, after crocodiles, and even after boats and cars, flipping the crafts and attacking the inhabitants. From time to time, someone will try to tame a hippo and keep it as a pet. This does not end well. Do not try this.

This story first ran in 2015.

Why Do Dogs Sniff Each Other's Butts?

Chloe Effron // Dogs: iStock
Chloe Effron // Dogs: iStock

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

We might giggle when we see dogs sniffing each other’s rear ends, but there’s a good reason why dogs stick their noses in private places. It lets them find out all kinds of things about each other to help them get along and survive. A butt sniff for dogs is like a handshake for humans.

Dogs’ amazing sense of smell is 10,000 to 100,000 times better than humans. They also have a special part of their noses called the Jacobson's organ that lets them ignore the smell of poop when they sniff another dog’s rear. Instead, the organ detects something more important. On the sides of a dog’s anus (AY-nuss)—the place where poop comes out—are special glands that release chemicals telling the body how to grow and work properly. This is what interests dogs the most about each other’s butts. 

The chemicals tell dogs a lot about each other. They help a dog to know if another dog is male or female, how old it is, what it eats, how healthy it is, and even what kind of mood they’re in. The chemicals also help it to know if other dogs are strangers or if they’ve met before. All of this helps dogs decide how they should behave. It's how dogs first get to know each other!

To sniff out more information about dogs and their noses (and their butts!), see this video by Reactions.

Do Lobsters Really Mate for Life?

iStock
iStock

It's a pop culture trope that mated lobsters stay together until they die. But is it true?

Nope. While plenty of animals practice long-term monogamy, lobsters are not among them. Lobsters actually mate by a weird system of serial monogamy. It's not exactly a one-night stand, but it's not a lifelong commitment either. Instead, a bunch of females take turns having a fling with the local dominant male that lasts a week or two and, if they're not happy with the amount of genetic material he's provided, then seek a little extra action.

It works like this: A female lobster who's ready to mate (which they can only do right after they've molted) hangs out near the den of the local dominant male and fans her pheromone-laced urine into his home. This relaxes the male, making him less aggressive and more receptive to mating. Then there's a brief courtship, and the male allows the female into his den.

Anywhere from a few hours to a few days later, the female slips into something a little more comfortable by shedding her exoskeleton. (Shacking up with the neighborhood tough guy guarantees her protection during this vulnerable time.) The pair mates, and the male deposits his sperm in the female. Once her new shell has hardened a week or two later, she takes off, and another female can have her turn. Often, the females in an area will stagger the timing of their molts to make their reproductive conga line more efficient. As soon as one female is done with the stud, the next one is already waiting to pee on his doorstep.

Sometimes, the male doesn't provide enough sperm to fully fertilize all of a female's eggs. In these cases, she'll leave before her new shell finishes forming to find and mate with another male (or males) until she collects enough sperm. Usually this requires just an extra dalliance or two, but as many as 10 have been reported.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER