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Rebecca O'Connell (istock)
Rebecca O'Connell (istock)

8 Adorable Animals That Are Surprisingly Violent

Rebecca O'Connell (istock)
Rebecca O'Connell (istock)

They’re cute. They’re cuddly. They’re killers. 

1. Koala 

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. Beaver 

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 Bancroft, Virginia. “There is no way I will swim in that place again,” she said. 

3. Cow 

Magret Bunzel-Drüke CC BY-SA 3.0 (Cow) // iStock (Nunchucks) 

Not all cows. But some cows. And those cows are terrifying. They’re called Heck cattle, also known—and I am not making this up—as “Nazi Super Cows.”

In the 1920s and '30s, German brother zoologists Heinz and Lutz Heck sought to recreate the extinct wild ox called the aurochs, which featured heavily in Teutonic mythology. They chose Spanish fighting cattle for their prehistoric shape and aggression, and envisioned a world where they could hunt these enormous, angry cows. Then, you know, World War II. The Nazis fell.

The uber-cows survived. They survive to this day, and available for purchase by those with a death wish. Farmer/photographer Derek Gow brought a herd of Heck cattle to his U.K. farm in 2009 and even successfully bred them before realizing he was in over his head. “They would try to kill anyone,” he told The Guardian. “Dealing with that was not a lot of fun at all.” 

4. Dolphin

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’s not 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 Dog

Devon Pike via Wikimedia Commons // Public Domain

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 Loris 

iStock

After the dolphin, the slow loris looks like a saint. A shy, weird, Cute Overload-worthy 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. This is probably not much comfort to someone who’s just been bitten.

7. Swan 


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 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 RSPCA agreed that Mr. Asbo was “out of control” and got a license to relocate the pair 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. Hippopotamus 


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 animals 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 Usain Bolt. They go after each other, after humans, after crocodiles, and even after boats and jeeps, flipping the crafts and attacking the inhabitants. From time to time, some guy will decide that Hippo Rules (i.e. Hippos Are Not for Hugging) don’t apply to him. This never ends well. Don’t be that guy. 

Remember: Wild animals are not for snuggling. Of all the species mentioned above, the most dangerous by far is Homo sapiens.

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Ted Cranford
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science
Scientists Use a CT Scanner to Give Whales a Hearing Test
Ted Cranford
Ted Cranford

It's hard to study how whales hear. You can't just give the largest animals in the world a standard hearing test. But it's important to know, because noise pollution is a huge problem underwater. Loud sounds generated by human activity like shipping and drilling now permeate the ocean, subjecting animals like whales and dolphins to an unnatural din that interferes with their ability to sense and communicate.

New research presented at the 2018 Experimental Biology meeting in San Diego, California suggests that the answer lies in a CT scanner designed to image rockets. Scientists in San Diego recently used a CT scanner to scan an entire minke whale, allowing them to model how it and other whales hear.

Many whales rely on their hearing more than any other sense. Whales use sonar to detect the environment around them. Sound travels fast underwater and can carry across long distances, and it allows whales to sense both predators and potential prey over the vast territories these animals inhabit. It’s key to communicating with other whales, too.

A CT scan of two halves of a dead whale
Ted Cranford, San Diego State University

Human technology, meanwhile, has made the ocean a noisy place. The propellers and engines of commercial ships create chronic, low-frequency noise that’s within the hearing range of many marine species, including baleen whales like the minke. The oil and gas industry is a major contributor, not only because of offshore drilling, but due to seismic testing for potential drilling sites, which involves blasting air at the ocean floor and measuring the (loud) sound that comes back. Military sonar operations can also have a profound impact; so much so that several years ago, environmental groups filed lawsuits against the U.S. Navy over its sonar testing off the coasts of California and Hawaii. (The environmentalists won, but the new rules may not be much better.)

Using the CT scans and computer modeling, San Diego State University biologist Ted Cranford predicted the ranges of audible sounds for the fin whale and the minke. To do so, he and his team scanned the body of an 11-foot-long minke whale calf (euthanized after being stranded on a Maryland beach in 2012 and preserved) with a CT scanner built to detect flaws in solid-fuel rocket engines. Cranford and his colleague Peter Krysl had previously used the same technique to scan the heads of a Cuvier’s beaked whale and a sperm whale to generate computer simulations of their auditory systems [PDF].

To save time scanning the minke calf, Cranford and the team ended up cutting the whale in half and scanning both parts. Then they digitally reconstructed it for the purposes of the model.

The scans, which assessed tissue density and elasticity, helped them visualize how sound waves vibrate through the skull and soft tissue of a whale’s head. According to models created with that data, minke whales’ hearing is sensitive to a larger range of sound frequencies than previously thought. The whales are sensitive to higher frequencies beyond those of each other’s vocalizations, leading the researchers to believe that they may be trying to hear the higher-frequency sounds of orcas, one of their main predators. (Toothed whales and dolphins communicate at higher frequencies than baleen whales do.)

Knowing the exact frequencies whales can hear is an important part of figuring out just how much human-created noise pollution affects them. By some estimates, according to Cranford, the low-frequency noise underwater created by human activity has doubled every 10 years for the past half-century. "Understanding how various marine vertebrates receive and process low-frequency sound is crucial for assessing the potential impacts" of that noise, he said in a press statement.

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Scientific Reports, Fernando Ramirez Rozzi
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Stones, Bones, and Wrecks
Humans Might Have Practiced Brain Surgery on Cows 5000 Years Ago
Scientific Reports, Fernando Ramirez Rozzi
Scientific Reports, Fernando Ramirez Rozzi

In the 1970s, archaeologists discovered a site in France containing hundreds of cow skeletons dating back 5000 to 5400 years. The sheer number wasn't surprising—human agriculture in that part of the world was booming by 3000 BCE. What perplexed scientists was something uncovered there a few decades later: a cow skull bearing a thoughtfully drilled hole. Now, a team of researchers has released evidence that suggests the hole is an early example of animal brain surgery.

Fernando Ramírez Rozzi, a paleontologist with the French National Center for Scientific Research, and Alain Froment, an anthropologist at the Museum of Mankind in Paris, published their findings in the journal Nature Scientific Reports. After comparing the opening to the holes chiseled into the skulls of humans from the same era, they found the bones bore some striking similarities. They didn't show any signs of fracturing from blunt force trauma; rather, the hole in the cow skull, like those in the human skulls, seemed to have been carved out carefully using a tool made for exactly that purpose. That suggests that the hole is evidence of the earliest known veterinary surgery performed by humans.

Trepanation, or the practice of boring holes into human skulls, is one of the oldest forms of surgery. Experts are still unsure why ancient humans did this, but the level of care that went into the procedures suggests that the surgery was likely used to treat sick patients while they were still alive. Why a person would perform this same surgery on a cow, however, is harder to explain.

The authors present a few theories, the first being that these ancient brain surgeons were treating a sick cow the same way they might treat a sick human. If a cow was suffering from a neural disease like epilepsy, perhaps they though that cutting a hole in its head would relieve whatever was agitating the brain. The cow would have needed to be pretty special to warrant such an effort when there were hundreds of healthy cows living on the same plot of land, as evidenced by the skeletons it was found with.

Another possible explanation was that whoever operated on the cow did so as practice to prepare them for drilling into the heads of live humans one day. "Cranial surgery requires great manual dexterity and a complete knowledge of the anatomy of the brain and vessel distribution," the authors write in the study. "It is possible that the mastery of techniques in cranial surgery shown in the Mesolithic and Neolithic periods was acquired through experimentation on animals."

Either way, the bovine patient didn't live to see the results of the procedure: The bone around the hole hadn't healed at all, which suggests the cow either died during surgery or wasn't alive to begin with.

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