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Snakes: Ian Macdonald / Art: Rebecca O'Connell

This Snake’s Venomous Powers Morph as It Grows Up

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Snakes: Ian Macdonald / Art: Rebecca O'Connell

Our relationship to food changes as we age. Our metabolisms slow. We start carrying antacids when going out to dinner. Sometimes we’ll even intentionally eat vegetables. But our transformation has nothing on the brown snake, whose venom gradually morphs to accommodate its new eating habits. Researchers described the snake’s enviable aging process in the journal Comparative Biochemistry and Physiology, Part C: Toxicology & Pharmacology.

Australian brown snakes (genus Pseudonaja) pack some of the most deadly venom in the world. As the authors of the new paper note, brown snakes are also “responsible for the majority of medically important human envenomations in Australia.” And that's saying something.

To better understand how that venom works, researchers collected samples from adult and juvenile snakes from nine known Pseudonaja species. Then they tested each venom’s effect on blood and other substances.

Eight out of the nine species showed a distinct change in venom action between the snake’s youth and adulthood. Brown snake venom is known for its anticoagulant, or blood clot–preventing, properties, which can lead to deadly strokes in small animals and internal bleeding in humans. But only the grown-ups’ venom contained anticoagulants. The babies’ toxic spit had its own power: attacking the nervous system, causing paralysis.

Juvenile (L) and adult (R) brown snakes.
Snakes: Stewart Macdonald / Art: Rebecca O'Connell

The venom’s transformation over time is not random, lead author Bryan Fry, of the University of Queensland, says, but a brilliant adaptation to the snake’s preferred diet at different stages in its life. Baby brown snakes eat tiny lizards, while adults prefer meatier—but scrappier—mammalian fare like rodents. They need a venom that knocks out their opponents fast.

"Young brown snakes may produce clinical symptoms like that of a death adder, as they seek out and paralyze sleeping lizards,” Fry said in a statement. "Once older, their venom contains toxins that cause devastating interference with blood clotting, causing rodent prey to become immobilized by stroke.”

Within the adult snakes’ venom lay another surprise. Scientists knew that brown snake venom worked by converting one blood protein into another, but other snakes do that, too, and their venom isn’t as fast-acting. Some other, hidden process, was going on, and Fry and his colleagues found it.

"Our team discovered brown snakes are potent in activating Factor VII, another blood-clotting enzyme, which is the missing (dark matter) element of brown snake envenomations,” he said. "The feedback loop created by this enzyme would become a venomous vortex and dramatically accelerate the effects upon the blood."

Reminder: It’s not that brown snakes want to be responsible for medically important human envenomations. Like sharks and bears, they’d much rather be left to go about their business. So the best thing for you, and them, is to leave them alone.

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Animals
14 Fascinating Facts About Foxes
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Foxes live on every continent except Antarctica and thrive in cities, towns, and rural settings. But despite being all around us, they’re a bit of a mystery. Here’s more about this elusive animal.

1. Foxes Are Solitary.

Foxes are part of the Canidae family, which means they’re related to wolves, jackals, and dogs. They’re medium-sized, between 7 and 15 pounds, with pointy faces, lithe frames, and bushy tails. But unlike their relatives, foxes are not pack animals. When raising their young, they live in small families—called a “leash of foxes” or a “skulk of foxes”—in underground burrows. Otherwise, they hunt and sleep alone.

2. Foxes Have A Lot In Common With Cats.

Like the cat, the fox is most active after the sun goes down. In fact, it has vertically oriented pupils that allow it to see in dim light. It even hunts in a similar manner to a cat, by stalking and pouncing on its prey.

And that’s just the beginning of the similarities. Like the cat, the fox has sensitive whiskers and spines on its tongue. It walks on its toes, which accounts for its elegant, cat-like tread. And—get this—many foxes have retractable claws that allow them to climb rooftops or trees. Some foxes even sleep in trees—just like cats.

3. The Red Fox Is The Most Common Fox.

The red fox has the widest geographical range of any animal in the order Carnivora. While its natural habitat is a mixed landscape of scrub and woodland, its flexible diet allows it to adapt to many environments. As a result, its range is the entire Northern Hemisphere, from the Arctic Circle to North Africa to Central America to the Asiatic steppes. It’s also in Australia, where it’s considered an invasive species.

4. Foxes Use The Earth’s Magnetic Field.

Like a guided missile, the fox harnesses the earth’s magnetic field to hunt. Other animals, like birds, sharks, and turtles, have this “magnetic sense,” but the fox is the first one we’ve discovered that uses it to catch prey.

According to New Scientist, the fox can see the earth’s magnetic field as a “ring of shadow” on its eyes that darkens as it heads towards magnetic north. When the shadow and the sound the prey is making line up, it’s time to pounce. Here’s the fox in action:

5. Foxes Are Good Parents.

Foxes reproduce once a year. Litters range from one to 11 pups (the average is six), which are born blind and don’t open their eyes until nine days after birth. During that time, they stay with the vixen (female) in the den while the dog (male) brings them food. They live with their parents until they're seven months old. The vixen protects her pups with surprising loyalty. Recently, a fox pup was caught in a trap in England for two weeks, but survived because its mother brought it food every day.

6. The Smallest Fox Weighs Under 3 Pounds.

Roughly the size of a kitten, the fennec fox has elongated ears and a creamy coat. It lives in the Sahara Desert, where it sleeps during the day to protect it from the searing heat. Its ears not only allow it to hear prey, they also radiate body heat, which keeps the fox cool. Its paws are covered with fur so that the fox can walk on hot sand, like it’s wearing snowshoes.

7. Foxes Are Playful.

Foxes are known to be friendly and curious. They play among themselves as well as with other animals like cats and dogs. They love balls, which they frequently steal from golf courses.

Although foxes are wild animals, their relationship with humans goes way back. In 2011, researchers opened a grave in a 16,500-year-old cemetery in Jordan to find the remains of a man and his pet fox. This was 4000 years before the first-known human and dog were buried together.

8. You Can Buy A Pet Fox.

In the 1960s, a Soviet geneticist named Dmitry Belyaev bred thousands of foxes before achieving a domesticated fox. Unlike a tame fox, which has learned to tolerate humans, a domesticated fox is docile toward people from birth. Today, you can buy a pet fox for $9000, according to Fast Company. They’re reportedly curious and sweet-tempered, although inclined to dig in your furniture.

9. Arctic Foxes Don’t Shiver Until –70 degrees Celsius.

The arctic fox, which lives in the northernmost areas of the hemisphere, can handle cold better than most animals on earth. It doesn’t even get cold until –70 degrees Celsius. Its white coat also camouflages it against predators. As the seasons change, the coat changes too, turning brown or gray so the fox can blend in with the rocks and dirt of the tundra.

10. Fox Hunting Continues To Be Controversial.

Perhaps because of the fox’s ability to decimate a chicken coop, in the 16th century, fox hunting became a popular activity in Britain. In the 19th century, the upper classes turned fox hunting into a formalized sport where a pack of hounds and men on horseback chase a fox until it is killed. Today, whether to ban fox hunting continues to be a controversial subject in the UK. Currently, fox hunting with dogs is not allowed.

11. The Fox Appears Throughout Folklore.

Examples include: the nine-tail fox from various Asian cultures; the Reynard tales from medieval Europe; the sly trickster fox from Native American lore; and Aesop’s “The Fox and the Crow.” The Finnish believed a fox made the Northern Lights by running in the snow so that its tail swept sparks into the sky. From this, we get the phrase “fox fires.”

12. Bat-eared Foxes Listen For Insects.

The bat-eared fox is aptly named, not just because of its 5-inch ears, but because of what it uses those ears for—like the bat, it listens for insects. On a typical night, the fox walks along the African Savannah, listening, until it hears the scuttle of prey. Although the fox eats a variety of insects and lizards, most of its diet is made up of termites. In fact, the bat-eared fox often makes its home in termite mounds, which it usually cleans out of inhabitants before moving in.

13. Darwin Discovered A Fox Species.

During his voyage on the Beagle, Charles Darwin collected a fox that today is unimaginatively called Darwin’s Fox. This small gray fox is critically endangered and lives in just two spots in the world: One population is on Island of Chiloé in Chile, and the second is in a Chilean national park. The fox’s greatest threats are unleashed domestic dogs that carry diseases like rabies.

14. Foxes Sound Like This.

Foxes make 40 different sounds, some of which you can listen to here. The most startling is the scream:

Pleasant dreams!

All images courtesy of iStock unless otherwise stated.

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Big Questions
Why Do Cats Love Scratching Furniture?
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Allergy suffering aside, cat ownership has proven health benefits. A feline friend can aid in the grieving process, reduce anxiety, and offer companionship.

The con in the cat column? They have no reservations about turning your furniture into shredded pleather. No matter how expensive your living room set, these furry troublemakers will treat it with the respect accorded to a college futon. Do cats do this out of some kind of spite? Are they conspiring with Raymour & Flanigan to get you to keep updating home decor?

Neither. According to cat behaviorists, cats gravitate toward scratching furniture mostly because that love seat is in a really conspicuous area [PDF]. As a result, cats want to send a message to any other animal that may happen by: namely, that this plush seating belongs to the cat who marked it. Scratching provides both visual evidence (claw marks) as well as a scent marker. Cat paws have scent glands that can leave smells that are detectable to other cats and animals.

But it’s not just territorial: Cats also scratch to remove sloughed-off nail tips, allowing fresh nail growth to occur. And they can work out their knotted back muscles—cramped from sleeping 16 hours a day, no doubt—by kneading the soft foam of a sectional.

If you want to dissuade your cat from such behavior, purchasing a scratching post is a good start. Make sure it’s non-carpeted—their nails can get caught on the fibers—and tall enough to allow for a good stretch. Most importantly, put it near furniture so cats can mark their hangout in high-traffic areas. A good post might be a little more expensive, but will likely result in fewer trips to Ethan Allen.

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