15 Incredible Ways Animals Stay Warm When It's Chilly
Winter is coming, and while humans have the option of adding layers of clothing or cranking up the furnace, animals have to rely on their biology or resources to stay warm in the wild. Here are some of the ways our furry and scaly friends survive the cold.
1. LEANING BACK
In addition to having a specialized circulatory system in their feet and flippers, emperor penguins often lean back onto their heels to get their toes off the ice. Their wedge-shaped tails provide stability, and there is no risk of losing heat because blood doesn’t flow through their tail feathers.
2. INCREASING BLOOD GLUCOSE LEVELS
Some reptiles and amphibians like the European common lizard have the ability to increase their glucose levels during the colder months so that lethal ice crystals won’t form and puncture their blood vessels. The process is reversed as temperatures rise.
3. RELAXING IN HOT SPRINGS
Most of the photos on the Internet of Japanese macaques show the pink-faced snow monkeys grooming one another in one of the country’s many natural spas. Known as onsens, the hot springs have become big tourist attractions, which has not deterred the monkeys from returning every winter.
4. MAKING ANTIFREEZE
Scientists have found that Alaskan wood frogs and other species take hibernation one step further: Their bodies freeze during the winter. Glucose in the blood prevents their cells from freezing and prevents dehydration, but all bodily processes (including heart and brain function) stop during this time. According to scientists, the frogs are essentially dead—until spring comes, temperatures rise, and the frogs spring to life again.
5. BUILDING SNOW BUNKERS
Burrowing into compressed snow traps air and creates an insulated pocket, just like how igloos work. Lemmings and other small animals build tunnel systems to stay safe from the wind, cold, and predators.
6. SHUTTING DOWN THEIR LUNGS
Scientists previously thought that freshwater turtles slipped into comas during cold winters, but a 2013 studyfound that the reptiles still responded to stimuli. Short of going completely comatose, the turtles slow their metabolisms and self-anesthetize, shutting down organs until warmer days return.
7. GROUP HUDDLE
What’s better than one body covered in layers of warm feathers? Try hundreds of them, standing flipper-to-flipper and moving in unison. Emperor penguins know that huddles are not just for football—they’re also a really good way to share the warmth. The wave of moving tuxedo-clad birds has been compared to a traffic jam, with the slightest movement by one penguin causing a ripple throughout the crowd. Research has also shown that the penguins are not crammed together, but instead stand barely touching so that no penguin’s feathers get compressed.
8. JUST KEEP FLYING
Some birds, like the Alpine swift, head for warmer climates in the winter. A study found that the swifts are able to stay in the air for six months at a time without touching the ground, subsisting on aerial plankton—a mix of small insects, bacteria, and spores found in the air—and forgoing sleep (scientists are divided as to whether the birds skip sleep completely, or catch some shut-eye during short periods spent gliding, rather than flapping). By the time the birds return to their starting location, they have six months to rest and refuel before they start their journey again.
9. BUILDING FAT RESERVES
Some animals eat more in the summer months so that they can store fat for the winter. The fat-tailed dwarf lemur, as the name suggests, uses its tail as a fat bank, increasing its body weight by as much as 40 percent.
10. DEEP SLEEP
Unlike other hibernating animals, North American black bears have the special ability to lower their metabolism without a dramatic drop in body temperature. What’s better than a toasty nap on a cold winter day?
11. STEALING HEAT FROM OTHERS
In a process called kleptothermy, reptiles like the tuatara steal the body heat of animals from completely different species. One study observed that the animals entered the nests of seabirds at night while the owners were still home so that they could benefit from the birds’ higher body temperature.
12. RELY ON HUMANS
Cats caught out in the cold often seek shelter under cars because the engines are an enticing source of heat (so always check before driving off). Smaller critters also enter homes in the winter to mooch off of the free warmth inside the walls.
13. GROWING INSULATION
It’s common for animals, from domestic dogs to wild foxes, to grow thicker fur as added insulation. It’s easier to grow than it is to get rid of—creatures like the elk of Colorado have to scratch or lick off their winter coats once the weather warms up.
14. GOING TORPID
Unlike hibernation, which is a long-term state, the torpor state happens in waves and can be frequent. Some species of birds enter torpor every day in the cold months to stay alive by lowering their heart and metabolic rates.
Some animals shiver to stay warm just like we do. And it’s not only the warm-blooded ones—bees also shiver by vibrating their muscles and keeping their wings still.
Getting a full eight hours of sleep can be tough these days. If you’re having trouble catching enough Zzzs, consider giving these highly rated and recommended products a try.
1. Everlasting Comfort Pure Memory Foam Knee Pillow; $25
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According to the National Sleep Foundation, too much light in a room when you’re trying to snooze is a recipe for sleep disaster. These understated polyester curtains from ECLIPSE block 99 percent of light and reduce noise—plus, they’ll help you save on energy costs. "Our neighbor leaves their backyard light on all night with what I can only guess is the same kind of bulb they use on a train headlight. It shines across their yard, through ours, straight at our bedroom window," one Amazon reviewer who purchased the curtains in black wrote. "These drapes block the light completely."
Being jarred awake by a blaring alarm clock can set the wrong mood for the rest of your day. Wake up in a more pleasant way with this clock, which gradually lights up between 10 percent and 100 percent in the 30 minutes before your alarm. You can choose between seven different colors and several natural sounds as well as a regular alarm beep, but why would you ever use that? “Since getting this clock my sleep has been much better,” one reviewer reported. “I wake up not feeling tired but refreshed.”
If you’re looking for an alarm clock with even more features, Philips’s SmartSleep Wake-Up Light is smartphone-enabled and equipped with an AmbiTrack sensor, which tracks things like bedroom temperature, humidity, and light levels, then gives recommendations for how you can get a better night’s rest.
Being too hot or too cold can kill a good night’s sleep. The Good Housekeeping Institute rated these sheets—which are made with Outlast fibers engineered by NASA—as 2020’s best temperature-regulating sheets.
If $159 sheets are out of your price range, the GHI recommends these sheets from Comfort Spaces, which are made with moisture-wicking Coolmax microfiber. Depending on the size you need, they range in price from $29 to $40.
This pillow—which has a 4.5-star rating on Amazon—is filled with memory foam scraps and microfiber, and comes with an extra half-pound of fill so you can add, or subtract, the amount in the pillow for ultimate comfort. As a bonus, the pillows are hypoallergenic, mite-resistant, and washable.
Though the science is still out on weighted blankets, some people swear by them. Wirecutter named this Baloo blanket the best, not in small part because, unlike many weighted blankets, it’s machine-washable and -dryable. It’s currently available in 12-pound ($149) twin size and 20-pound ($169) queen size. It’s rated 4.7 out of five stars on Amazon, with one reviewer reporting that “when it's spread out over you it just feels like a comfy, snuggly hug for your whole body … I've found it super relaxing for falling asleep the last few nights, and it looks nice on the end of the bed, too.”
Few things can disturb your slumber—and that of the ones you love—like loudly sawing logs. Philips’s Smartsleep Snoring Relief Band is designed for people who snore when they’re sleeping on their backs, and according to the company, 86 percent of people who used the band reported reduced snoring after a month. The device wraps around the torso and is equipped with a sensor that delivers vibrations if it detects you moving to sleep on your back; those vibrations stop when you roll onto your side. The next day, you can see how many hours you spent in bed, how many of those hours you spent on your back, and your response rate to the vibrations. The sensor has an algorithm that notes your response rate and tweaks the intensity of vibrations based on that. “This device works exactly as advertised,” one Amazon reviewer wrote. “I’d say it’s perfect.”
Whether you're a Jaws fanatic or just want to live every week like it's Shark Week, you'll want to read up on these fascinating facts about sharks, adapted from an episode of The List Show on YouTube.
1. There are more than 500 types of sharks.
They range in size from 8 inches to 40 feet long.
2. The cookie cutter shark grows to up to 22 inches.
The cookie cutter shark uses its suction-cup-like lips to attach itself to prey. Once it’s firmly stuck on there, the shark spins its body, using its bottom row of serrated teeth to take out a cone-shaped chunk of flesh. Typically, cookie cutters feed off of sea creatures much bigger than them, but they’ve also taken bites out of a couple of humans … and they’ve been known to leave their mark on submarines, too.
3. Peter Benchley’s 1974 novel Jaws was inspired by a fisherman who caught a 4500-pound behemoth in Montauk in 1964.
The novel wasn’t always going to be called Jaws: Alternate titles included “The Stillness in the Water,” “The Silence of the Deep,” “Leviathan Rising,” and “The Jaws of Death."
4. Peter Benchley later became a shark conservationist.
He used his pen to tackle misconceptions about the fish. In 2006, he said, “I could never write that book today. Sharks don’t target human beings and they certainly don’t hold grudges.” Fun fact: Benchley makes a cameo in Steven Spielberg’s 1975 movie adaptation of his novel. He plays a TV news reporter.
5. Shark attacks are very rare.
In 2018, there were 66 confirmed unprovoked attacks. In America, the risk of dying from a shark attack is 1 in 3,748,067. You’re more likely to be killed by fireworks, a train crash, or MRSA—that antibiotic-resistant bacteria—than you are by sharks. Worldwide, the risk is even lower.
6. Sharks have been around for a while.
Thanks to fossils, we know that they’ve been swimming the seas for at least 400 million years.
7. Some species of shark can live to be incredibly old.
Researchers in 2016 used radiocarbon dating on the eyes of 28 Greenland sharks and determined that one female might have been around 400 years old.
8. Greenland shark meat is a delicacy in Iceland called hákarl.
The shark’s meat is toxic when fresh, so it has to go through a fermentation process that involves burying the shark’s body in sand under rocks for six to 12 weeks. The meat is then cut up and hung to dry. The finished product has a strong scent of ammonia. Anthony Bourdain called it "the single worst, most disgusting and terrible tasting thing" he’d ever eaten.
9. Great white sharks have a man-eating reputation, but they’re much more interested in seals and sea lions.
Great whites have a 40 to 55 percent accuracy rate in catching their seal prey, according to research. The hunting process also often involves the sharks coming fully out of the water, which is called breaching.
10. Great whites are fast.
They can swim at 35mph for short bursts.
11. Many shark researchers think the old tale of “great whites attack humans because they think we’re seals” is a myth.
Great white shark attacks on humans are much less vicious than the way sharks attack prey like seals and sea lions—one study reported that in 76 percent of attacks on surfers the force would not have stunned a pinniped. In most cases they’re probably just curious—though still potentially deadly. One expert told Discovery that if you do see a shark, the safest thing to do is to remain calm and try to slowly and calmly get back to safety.
12. Great white sharks typically aren’t found in aquariums—though not for lack of trying.
Since the 1970s, aquarium workers who have tried to keep the sharks in captivity have been having basically the same tragic experience: finding a captive great white shark sick, then dead, within a week. While in enclosures, the sharks can't swim at the high speeds or over the distances they're supposed to, so they bump into the glass and get hurt or just stop swimming and die. Younger sharks have tended to do better: The Monterey Bay Aquarium was able to keep a young great white for 198 days, but released her after she started going after other sharks.
13. Tiger sharks and sand tiger sharks aren't the same.
Another shark you probably won’t see in captivity these days is the tiger shark—not to be confused with the sand tiger shark, which is a completely different species found in aquariums around the world.
14. Female tiger sharks have many, many pups.
After 13 to 16 months of pregnancy, a female might give birth to between 10 and 82 little shark babies. The average is around 30.
15. It’s not unusual for a female shark to give birth to her pups in the place where she herself was born.
One study, which began in 1995 and concluded in 2012, found this to be the case with lemon sharks in the Bahamas.
16. Female mako sharks stay away from male makos.
In research that lasted for four months, a biologist and his team recorded 264 male and 132 female mako sharks in the Easter Island area. They found that there was a clear divide between where males resided versus females. They were baffled as to why. One of them suggested that it might have to do with the fact that males often bite their intended mate, so maybe the females were trying to avoid that whole situation. Fun fact: Biting is often a part of shark copulation, because the males have to hang on to something.
17. It’s not just biologists who have taken an interest in sharks.
In 2002, software programmer Jason Holmberg went scuba diving on vacation and spotted the rare whale shark. He wanted to make the spotted sharks less mysterious, so he teamed up with an astrophysicist and a marine biologist. They were able to adapt an algorithm that had been created for the Hubble Space Telescope program and use it to start identifying sharks. The algorithm was initially for star mapping, so it made sense as an algorithm for shark spot mapping. They’ve since created a database with 32,000 pictures of whale sharks. The database has helped them track the animals’ locations, which means they can learn more about the whale shark lifestyle.
18. The shape of hammerhead sharks' heads might help with hunting.
Sharks are able to sense electric fields in water, which allows them to determine if they’re in the vicinity of prey. One theory is that hammerhead sharks have more of those sensory organs in their heads, so they can find prey better. Their eyes being so far apart helps too—they have better binocular vision.
19. Shark embryos can sense predators.
In addition to using electric fields to sense prey, sharks also use them to sense predators. Even shark embryos have that ability. In a study published in 2013, a group studying brownbanded bamboo shark embryos found that when the embryos were in the electric field of a predator, their gills would stop moving.
20. Sharks sometimes like to rest in groups.
Nurse sharks and whitetip reef sharks have been observed gathering in groups of 2 to 40, usually in a safe place like a crevice, often just napping.
21. A basking shark looks very weird when it decomposes.
It quickly loses parts of its jaw and tail. So it’s not unusual for people who spot a decomposing basking shark on the shore to believe that they’ve found a sea monster. This happened in 1970 in Massachusetts.
22. A tiger shark once puked up evidence of a murder.
During the 1930s, a tiger shark at Coogee Aquarium in Australia vomited a human arm, evidence that became part of a murder trial. Thanks to a tattoo on the arm, the person it belonged to, James Smith, was identified. It turned out that he was missing—and the shark hadn’t bitten the arm off, it was cut off with a knife. There was a suspect, Patrick Brady, and a man willing to testify that Brady was responsible. But that witness was shot before the trial. Brady’s lawyer claimed that for a homicide, there needed to be a body and all they had was an arm. Brady went free. The shark unfortunately died.
23. The goblin shark eats using "slingshot feeding."
The deep-sea-dwelling goblin shark has a jaw that shoots outward to grab prey in what scientists have dubbed “slingshot feeding,” so it’s no wonder they often get compared to monsters. The goblin shark can deploy its jaw at 10.1 feet per second—roughly twice the speed that New York City pedestrians walk.
24. The goblin shark is named after a Japanese demon.
Japanese fishermen named the sharks tengu-zame. Tengu is a demon with a long nose that sometimes steals children. And zame means “shark.” That’s how we got our English translation: goblin shark.
25. Not all sharks are ferocious carnivores.
The bonnethead shark has long been observed to eat seagrass—up to 62.1 percent of gut content mass. Until recently it was unclear if they were digesting it. But in 2018 it was confirmed through stable isotope analysis that they actually were, making them the first known omnivorous shark.
26. There are multiple types of lantern sharks, including a dwarf lantern shark that doesn’t grow larger than 8 inches.
These sharks have bellies and fins that glow. So it’s thought that when there’s a predator swimming beneath them, the predator doesn’t know the difference between the shark and the light coming into the ocean from the sun.
27. Not all sharks are strictly ocean dwellers.
Bull sharks are unusual in that they can tolerate fresh water. Most sharks have to be in salt water because that’s what their bodies can handle—put them in fresh water and they’ll lose too much salt. But bull sharks are better able to retain salt in their bodies, so they can travel in fresh water. And in fact, in 1937, one was caught in Alton, Illinois, 1000 miles up the Mississippi River from the Gulf of Mexico, where you wouldn’t typically expect to encounter a shark.
28. Megalodon sharks were huge—maybe about 50 feet long.
But there are now theories that the measly great white shark, at less than half that size, may have caused them to go extinct. It was previously believed that megalodons went extinct around 2.6 million years ago, but when a group of paleontologists and geologists went back through the fossils and data, they pegged it at 3.6 million years ago—which just so happened to be the time that great white sharks were emerging. They were probably able to go head-to-head with younger megalodons and out-compete them for food.
29. Megalodon shark teeth could be around 7 inches long.
And in fact, you might want to be on the lookout for them. In 2018, a couple found a fossilized megalodon tooth on a beach in North Carolina.
30. An American president had a megalodon tooth.
Thomas Jefferson loved fossils and even kept some on display at the entrance of Monticello. Today, his megalodon tooth is at the Academy of Natural Sciences in Philadelphia. Of course, he signed it.
31. The song "Baby Shark" used to be sung by kids at camps.
Before Pinkfong’s version of “Baby Shark” became one of the most viewed YouTube videos of all time, it was a common song for kids to sing at camps. But when Johnny Only turned it into the bop that we all get stuck in our heads today, he did change some things. In the original lyrics, the sharks attack people and even kill them. Peter Benchley would not approve.