7 Science-Approved Tips for Walking Across Ice

iStock
iStock

Unless you live in a warm climate year-round where the only ice you experience involves cubes that tumble from your refrigerator door, the issue of slipping on the slick surface presents a serious concern. After all, news segments talk of treacherous conditions where people unable to gain traction slide themselves into oblivion just crossing the street. On the work front, the Bureau of Labor Statistics reports that in 2014, ice, snow, or sleet caused more than 42,000 injuries and illnesses.

And of course, there will always be viral ice-slipping videos floating around, like the one of the man who slid along the entire length of his driveway.

The very act of walking is a balancing act we take for granted. "Walking is like falling and catching yourself over and over," says Kayla Lewis, Ph.D., an assistant professor of physics at New Jersey's Monmouth University. "You lean forward and fall forward, catching yourself with your leading leg to prepare for the next step. But it's the friction between the ground and your shoes that enables you to save yourself this way; it prevents your front shoe from sliding forward and your back shoe from sliding backward."

All of this begs the question: What's the best way to walk on ice to minimize the risk of falling? To safely sashay over ice, follow the experts' advice below. Don't let their words of wisdom, you know, slip away from you.

1. MOVE SLOWLY AND STEADILY.

Clearly, instinct and common sense kicks in the moment you approach the slick surface, telling us it's virtually impossible (and not really wise) to sprint across an ice-covered driveway. Slow and easy wins the proverbial race, right?

Yes. According to Philip E. Martin, Ph.D., professor and chair of the Department of Kinesiology at Iowa State University, minimizing forward and backward force is indeed essential when walking on ice. "What's key is trying to keep force applied to the ground more vertically so there's less force forward and backward—because that's the part that requires friction," he tells Mental Floss.

2. TAKE SHORTER STEPS.

What does reducing forward-and-backward force mean practically? Taking shorter steps. When we do so, the forces applied against the ground in forward and backwards directions are reduced. Therefore, Martin says, we're not pushing as hard and are "adapting our gait to work with the reduced friction that's available to us."

3. AVOID MELTING ICE.

Mark Fahnestock, a glaciologist and research professor at the University of Alaska Fairbanks, has been studying glaciers and ice sheets for the last couple of decades, and during that time has experienced conditions at -40°F in Alaska. He says that how slippery ice becomes can vary by temperatureso being aware of temperatures can help you figure out how easy or challenging it may be to cross ice. "It's easier to walk on ice at 0°F or -20°F," he tells Mental Floss. "Ice is much slipperier when it's really melting."

Chalk that up to a film of molecules on the surface that behaves like water, he says, which "becomes more pronounced" in warmer temperatures. However, this isn't to say you won't ever slip on ice the colder the temperature gets; he emphasizes, "It's not that it's not slippery, it's just that it's not as slippery as when it's warmer."

4. GO AROUND SLOPES AND STAIRS WHEN YOU CAN.

You should also be mindful of the surface you're about to set foot on. A flat surface is one thing, but Fahnestock says that "if it's slanted where your foot meets a driveway, for example, it's not holding your weight—rather, it's your weight that's causing your foot to move."

"Gravity is going to do its thing whether you like it or not," Martin says, especially if there's an icy slope that's in a significantly downhill direction. Unfortunately, in this circumstance, you probably won't be able to adapt your gait to prevent slipping, so it's likely it'll be a score of Ice 1, Human 0.

ice caution sign next to person who slipped on ice
iStock

Stairs can make navigating ice even more treacherous, but we know it's not always possible to avoid them. According to helpful hints for walking on ice from Iowa State University, when dealing with icy steps, be sure to use handrails, keeping your hands out of your pockets, and continue to move slowly.

5. KEEP AN EYE OUT FOR CHANGING SURFACES.

Then there are circumstances where the surface characteristics can change without us realizing it. But Martin says not to fret if you're walking on a straight, dry surface and suddenly encounter an icy patch you weren't expecting. Maximum friction force is reduced when you encounter this abrupt change, causing you to quickly alter your gait. Sure, you may slip a little since it initially throws you off guard, but "humans are pretty adaptable and recognize challenges quickly," Martin says. We pay closer attention to surface characteristics than we may consciously realize, and we adjust our stride patterns automatically.

6. WEAR THE RIGHT SHOES.

And don't forget the benefits of appropriate footwear. Martin encourages people to consider a shoe's material properties, noting that a rigid leather sole is far from ideal as it offers a significantly weaker grip compared to a rubber sole. Of course, traction-improving treads, cleats, or spikes can help too.

Scientists are studying how traction varies among consumer boots. A team of researchers at iDAPT, the research arm of the Toronto Rehabilitation Institute—University Health Network, has tested and rated the slip resistance of nearly 100 boots and spikes in their WinterLab, where they study slips and falls on a floor composed entirely of ice. Testers secured into safety harnesses walk back and forth across the ice as the researchers slowly increase the angle of the floor until the tester slips. The angle at which they slip is called the "maximum achievable angle": The higher the angle, the better the slip resistance.

More than 80 percent of the boots they've tested failed to score high enough on the MAA to earn a single "snowflake" on iDAPT's three-snowflake scale, including those from popular brands like Timberland, Sorel, and Terra. The top ranked, with three snowflakes, are all Stabil spikes, which attach to your regular shoes or boot.

7. WHEN ALL ELSE FAILS, WADDLE.

Consider taking an ice-walking cue from those waddling tuxedoed ice pros: Walk like a penguin. Fahnestock says shuffling helps keep your weight in a straight-down stance, allowing your feet to carry your weight carefully and minimize slipping.

Could Gigantic Coconut Crabs Have Played a Part in Amelia Earhart’s Mysterious Disappearance? At Least One Scientist Thinks So

Getty Images
Getty Images

Amelia Earhart's disappearance during her attempt to fly around the world has captivated historians and conspiracy theorists for more than 80 years. One organization is now suggesting that her fate may have been sealed by giant crabs.

The International Group for Historic Aircraft Recovery (TIGHAR) believes that Amelia Earhart and navigator Fred Noonan may have landed their plane on Nikumaroro Island when they couldn't find their target, Howland Island, and that Nikumaroro's endemic crustaceans may have played a part in the ensuing mystery.

According to National Geographic, there are several clues supporting TIGHAR's theory. The large reef that hugs Nikumaroro’s coast makes it conducive to emergency aircraft landings. In 1940—just three years after Earhart’s disappearance—British colonists found 13 human bones beneath a ren tree on the island and shipped them to Fiji, where they were lost. The colony's administrator, Gerald Gallagher, sent a telegram back to England positing that it was Earhart’s skeleton. Then, in 2001, researchers uncovered U.S.-made artifacts around the ren tree including a jackknife, a woman’s compact, a zipper, and glass jars. The plot thickened even further in 2017, when four forensic bone-sniffing dogs all indicated that a human had indeed died at the site, though excavators failed to dig up any more evidence.

If those 13 bones beneath the ren tree did belong to the unfortunate castaway, where are the rest of her remains? Tom King, TIGHAR’s former chief archaeologist, thinks that coconut crabs can answer that question.

Nikumaroro is home to thousands of the colossal creatures, which can grow to a terrifying 3 feet across and weigh 9 pounds. They’re sometimes called robber crabs because of their penchant for absconding with objects that smell like food, and they’ll eat practically anything—coconuts, fruit, birds, rodents, other crabs, their own discarded body parts, and carrion.

It’s not unreasonable, then, to think that coconut crabs may have feasted on Earhart’s corpse and then taken her bones home with them. In one experiment to test the theory, TIGHAR researchers deposited a pig carcass on the island and filmed the aftermath. With the help of small strawberry hermit crabs, coconut crabs stripped the pig down to the bone in two weeks. After a year, some of the bones had been dragged 60 feet from the carcass’s original location, and some were never recovered at all.

King believes Earhart’s missing 193 bones could be hidden in the burrows of various coconut crabs. As in the pig experiment, crabs may have scattered some of Earhart’s bones dozens of feet away, but maybe not all of them—after all, the forensic dogs smelled bones near the ren tree that haven’t yet been located. Right now, TIGHAR is working with the Canine Forensics Foundation to further explore the area.

While we wait for more answers, dive into these other theories about Earhart’s disappearance.

[h/t National Geographic]

10 Juicy Facts About Leeches

Ian Cook
Ian Cook

Leeches get a bad rap, but they’re actually pretty cool once you get to know them—and we're finding out more about them, even today. Recently, a team led by Anna Phillips, curator of parasitic worms at the Smithsonian National Museum of Natural History, discovered a new species of medicinal leech (pictured above) in a Maryland swamp. We asked parasite expert and curator at the American Museum of Natural History Mark E. Siddall to share some surprising facts about the worms we love to hate. 

1. Not all leeches suck blood.

Hematophagous, or blood-feeding, species are only one type of leech. “The vast majority of species are [hematophagous],” Siddall tells Mental Floss, “but it depends on the environment. In North America, there are probably more freshwater leeches that don’t feed on blood than there are blood-feeders.” And even among the hematophagous species, there are not too many who are after you. “Very few of them are interested in feeding on human blood,” Siddall says. “Certainly they’ll do it, if they’re given the opportunity, but they’re not what they’re spending most of their time feeding on.” 

2. Leeches are everywhere.

Japanese leech on a log
Pieria, Wikimedia Commons // Public Domain

“Every continent on the planet has leeches, with the exception of Antarctica,” Siddall says. “And even then there are marine leeches in Antarctic waters.” Humans have co-existed with leeches for so long, according to Siddall, that just about every language has a word for leech. 

3. Leeches have made a comeback in medicine.

Bloodletting for bloodletting’s sake has fallen out of favor with Western physicians, but that doesn’t mean medicinal leeches are enjoying a cushy retirement. Today, surgeons keep them on hand in the operating room and use them as mini-vacuums to clean up blood. “That is a perfectly sensible use of leeches,” Siddall says. Other uses, though, are less sensible: “The more naturopathic application of leeches in order to get rid of bad blood or to cure, I don’t know, whatever happens to ail you, is complete hooey,” he says. How on Earth would leeches take away bad blood and leave good blood? It’s silly.” 

4. Novelist Amy Tan has her own species of leeches.

Land-based leeches made an appearance in Tan’s 2005 book Saving Fish from Drowning, a fact that instantly put the author in leech researchers’ good graces. “There are not a lot of novels out there with terrestrial leeches in them,” Siddall says. So when he and his colleagues identified a new species of tiny terrestrial leeches, they gave the leech Tan’s name. The author loved it. “I am thrilled to be immortalized as Chtonobdella tanae,” Tan said in a press statement. “I am now planning my trip to Queensland, Australia, where I hope to take leisurely walks through the jungle, accompanied by a dozen or so of my namesake feeding on my ankles.”

5. Leeches can get pretty big.

The giant Amazon leech (Haementeria ghilianii) can grow up to 18 inches and live up to 20 years. And yes, this one’s a blood-feeder. Like all hematophagous species, H. ghilianii sticks its proboscis (which can be up to 6 inches long) into a host, drinks its fill, and falls off. Scientists thought the species was extinct until a zoologist found two specimens in the 1970s, one of whom he named Grandma Moses. We are not making this up.

6. Leeches make good bait.

Many walleye anglers swear by leeches. “A leech on any presentation moves more than other types of live bait," pro fisher Jerry Hein told Fishing League Worldwide. "I grew up fishing them, and I think they're the most effective live bait around no matter where you go." There’s an entire leech industry to provide fishers with their bait. One year, weather conditions kept the leeches from showing up in their typical habitats, which prevented their collection and sale. Speaking to CBS news, one tackle shop owner called the absence of leeches “the worst nightmare in the bait industry.”

7. Leech scientists use themselves as bait.

Siddall and his colleagues collect and study wild leeches. That means hours of trekking through leech territory, looking for specimens. “Whether we’re wandering in water or traipsing through a bamboo forest,” Siddall says, “we are relying on the fact that leeches are attracted to us.” Do the leeches feed on them? “Oh my god, yes. We try to get them before they feed on us … but sometimes, obviously, you can’t help it.”

8. Leech sex is mesmerizing.

Like many worms, leeches are all hermaphroditic. The specifics of mating vary by species, but most twine themselves together and trade sperm packets. (The two leeches in the video above are both named Norbert.)

9. Some leech species make surprisingly caring parents. 

“There’s a whole family of leeches that, when they lay their eggs, will cover them with their own bodies,” Siddall says. “They’ll lay the eggs, cover them with their bodies, and fan the eggs to prevent fungus or bacteria from getting on them, and then when the eggs hatch, they will attach to the parent. They’re not feeding on the parent, just hanging on, and then when the parent leech goes to its next blood meal it’s carrying its offspring to its next blood meal. That’s pretty profound parental care, especially for invertebrates.”

10. You might be the next to discover a new leech species. 

Despite living side-by-side with leeches for thousands of years, we’ve still got a lot to learn about them. Scientists are aware of about 700 different species, but they know there are many more out there. “I’ll tell you what I wish for,” Siddall says. “If you ever get fed on by a leech, rather than tearing off and burning it and throwing it in the trash, maybe observe it and see if you can see any color patterns. Understand that there’s a real possibility that it could be a new species. So watch them, let them finish. They’re not gonna take much blood. And who knows? It could be scientifically useful.”

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