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Why Don't Octopuses Get Stuck to Themselves?

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Life can't be easy for octopuses. Sure, they're universally loved for changing color, opening jars from the inside, and predicting the winners of World Cup games. But they have eight very flexible arms to keep track of, which aren't even under their full control. Each arm is fairly autonomous, and a lot of the motor control happens in the neural circuitry of the arms themselves instead of the brain.

Forget about the left hand not knowing what the right hand is doing. At any given moment, not a single octopus tentacle knows what the other seven are up to—and neither does the octopus.

Not only are these eight arms writhing around unhindered by elbows, wrists, or a central control system, but each one is also covered in hundreds of suckers that that will reflexively stick to just about anything. You would think that this would lead to octopuses getting tangled up in themselves pretty regularly, but it doesn't.

A new paper shows why: The one thing that the suckers don't stick to is the octopus' own skin.

For about an hour after amputation, an octopus arm pretty much acts as if it were still attached. It moves similarly, while the suckers grasp and stick to things they touch. In what must have looked like a darkly surreal experiment to anyone who stumbled upon it, a team of Israeli and American scientists observed what these flailing arms would and wouldn't grab.

In more than 30 trials, the researchers found that the suckers wouldn't attach to another octopus arm, whether it came from the same animal or a different one. Nor would they latch on to a petri dish that was covered in octopus skin.

They would grab another arm if it had been skinned, though. And if a petri dish was only partially covered, the suckers held the exposed plastic but avoided the skin.

It was starting to look like the skin made all the difference, so the researchers coated petri dishes in a gel that was soaked in dissolved chemicals extracted from the octopus skin. When they offered these to the amputated arms, the suckers grabbed them, but with 10 to 20 times less force than they did the regular, uncoated ones.

This confirmed that some chemical in the skin hinders the attachment reflex, thereby preventing the suckers from sticking. For the octopus, this means that each arm keeps the others from grabbing hold of it without the octopus having to worry about the details.

Interestingly, live octopuses have the ability to override the sucker-stopping signal when they want to. In another experiment, live animals showed they could grab amputated arms, but were less likely to do so if the arm had been one of their own. This suggests that they can tell their own limbs from another's. Furthermore, it's possible that their skin-recognition trick might involve the brain, and isn't limited to skin-sucker interactions.

Still, it's unclear which specific chemical prevents sucker attachment. Researchers think the mystery chemical probably acts on the chemical receptors in the individual suckers.

However it works, the self-avoidance system, the researchers say, is a "striking addition to the list of surprises" in the octopus' body. It not only keeps octopuses from tying themselves in knots, but also frees them up to do all the cool things we love them for.

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Authorities Want This Roadside Bear Statue in Wales Removed Before It Causes More Accidents
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There are no real bears in the British Isles for residents to worry about, but a statue of one in the small Welsh town of Llanwrtyd Wells has become a cause of concern. As The Telegraph reports, the statue is so convincing that it's scaring drivers, causing at least one motorist to crash her car. Now road safety officials are demanding it be removed.

The 10-foot wooden statue has been a fixture on the roadside for at least 15 years. It made headlines in May of 2018 when a woman driving her car saw the landmark and took it to be the real thing. She was so startled that she veered off the road and into a street sign.

After the incident, she complained about the bear to highways officials who agreed that it poses a safety threat and should be removed. But the small town isn't giving in to the Welsh government's demands so quickly.

Wooden bear statue.

The bear statue was originally erected on the site of a now-defunct wool mill. Even though the mill has since closed, locals still see the statue as an important landmark. Llanwrtyd Wells councilor Peter James called it an "iconic gateway of the town," according to The Telegraph.

Another town resident, who wished to remain anonymous, told The Telegraph that the woman who crashed her car had been a tourist from Canada where bears are common. Bear were hunted to extinction in Britain about 1000 years ago, so local drivers have no reason to look out for the real animals on the side of the road.

The statue remains in its old spot, but Welsh government officials plan to remove it themselves if the town doesn't cooperate. For now, temporary traffic lights have been set up around the site of the accident to prevent any similar incidents.

[h/t The Telegraph]

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10 Scientific Benefits of Being a Dog Owner
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The bickering between cat people and dog people is ongoing and vicious, but in the end, we're all better off for loving a pet. But if anyone tries to poo-poo your pooch, know that there are some scientific reasons that they're man's best friend.

1. YOU GET SICK LESS OFTEN.

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If cleaning commercials are to be believed, humanity is in the midst of a war against germs—and we shouldn't stop until every single one is dead. In reality, the amount of disinfecting we do is making us sicker; since our bodies are exposed to a less diverse mix of germs, our entire microbiome is messed up. Fortunately, dogs are covered in germs! Having a dog in the house means more diverse bacteria enters the home and gets inside the occupants (one study found "dog-related biodiversity" is especially high on pillowcases). In turn, people with dogs seem to get ill less frequently and less severely than people—especially children—with cats or no pets.

2. YOU'RE MORE RESISTANT TO ALLERGIES.

Child and mother playing with a dog on a bed.
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While dog dander can be a trigger for people with allergies, growing up in a house with a dog makes children less likely to develop allergies over the course of their lives. And the benefits can start during gestation; a 2017 study published in the journal Microbiome found that a bacterial exchange happened between women who lived with pets (largely dogs) during pregnancy and their children, regardless of type of birth or whether the child was breastfed, and even if the pet was not in the home after the birth of the child. Those children tested had two bacteria, Ruminococcus and Oscillospira, that reduce the risk of common allergies, asthma, and obesity, and they were less likely to develop eczema.

3. YOU'LL HAVE BETTER HEART HEALTH.

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Everything about owning a dog seems to lend itself to better heart health. Just the act of petting a dog lowers heart rate and blood pressure. A 2017 Chinese study found a link between dog ownership and reduced risk of coronary artery disease, while other studies show pet owners have slightly lower cholesterol and are more likely to survive a heart attack.

4. YOU GET MORE EXERCISE.

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While other pets have positive effects on your health as well, dogs have the added benefit of needing to be walked and played with numerous times a day. This means that many dog owners are getting 30 minutes of exercise a day, lowering their risk of cardiovascular disease.

5. YOU'LL BE HAPPIER.

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Dog owners are less likely to suffer from depression than non-pet owners. Even for those people who are clinically depressed, having a pet to take care of can help them out of a depressive episode. Since taking care of a dog requires a routine and forces you to stay at least a little active, dog owners are more likely to interact with others and have an increased sense of well-being while tending to their pet. The interaction with and love received from a dog can also help people stay positive. Even the mere act of looking at your pet increases the amount of oxytocin, the "feel good" chemical, in the brain.

6. YOU HAVE A MORE ACTIVE SOCIAL LIFE.

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Not only does dog ownership indirectly tell others that you're trustworthy, your trusty companion can help facilitate friendships and social networks. A 2015 study published in PLOS One found that dogs can be both the catalyst for sparking new relationships and also the means for keeping social networks thriving. One study even showed that those with dogs also had closer and more supportive relationships with the people in their lives.

7. YOUR DOG MIGHT BE A CANCER DETECTOR.

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Your dog could save your life one day: It seems that our canine friends have the ability to smell cancer in the human body. Stories abound of owners whose dogs kept sniffing or licking a mole or lump on their body so they got it checked out, discovering it was cancerous. The anecdotal evidence has been backed up by scientific studies, and some dogs are now trained to detect cancer.

8. YOU'LL BE LESS STRESSED AT WORK.

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The benefits of bringing a dog to work are so increasingly obvious that more companies are catching on. Studies show that people who interact with a pet while working have lower stress levels throughout the day, while people who do not bring a pet see their stress levels increase over time. Dogs in the office also lead to people taking more breaks, to play with or walk the dog, which makes them more energized when they return to work. This, in turn, has been shown to lead to much greater productivity and job satisfaction.

9. YOU CAN FIND OUT MORE ABOUT YOUR PERSONALITY.

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The kind of dog you have says a lot about your personality. A study in England found a very clear correlation between people's personalities and what type of dogs they owned; for example, people who owned toy dogs tended to be more intelligent, while owners of utility dogs like Dalmatians and bulldogs were the most conscientious. Other studies have found that dog owners in general are more outgoing and friendly than cat owners.

10. YOUR KIDS WILL BE MORE EMPATHETIC.

A young boy having fun with his dog.
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Though one 2003 study found that there was no link between pet ownership and empathy in a group of children, a 2017 study of 1000 7- to 12-year-olds found that pet attachment of any kind encouraged compassion and positive attitudes toward animals, which promoted better well-being for both the child and the pet. Children with dogs scored the highest for pet attachment, and the study notes that "dogs may help children to regulate their emotions because they can trigger and respond to a child's attachment related behavior." And, of course, only one pet will happily play fetch with a toddler.

A version of this story originally ran in 2015.

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