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A Tiny Spider’s Secret to Taking Down Big Prey

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Pekar, et al.

At first glance, the pinhead-sized spider Zodarion cyrenaicum seems like it's on a suicide mission every time it hunts for a meal. Its preferred prey is a desert ant, Messor arenarius, some three times bigger and six times heavier than itself. But as David and the Red Viper have shown us, size isn’t everything—especially if you’ve got some slick moves and the right tools for the job. 

Wondering how the spiders consistently come out on top when battling the relatively-giant ants, Czech scientists watched some captured critters hunt in their lab. 

They found that both adult female and juvenile spiders rely on a potent venom that can immobilize an ant with just one bite. They use slightly different tactics to stay out of harm’s way until the venom does its job, though. (The adult males don’t hunt at all, and instead take a cut of the food from a female's or juvenile’s kill).

The adult female spiders attack quickly from behind, biting the ant’s abdomen or hind leg, and then retreat from any counter-attacks until the ant falls.

Following a bite, the ant stopped moving and stood still with opened mandibles,” the researchers write. “Meanwhile, the bitten limb contracted, and the gaster [the bulbous hind end of the ant body] bent under the thorax. Such a C-shaped position lasted for several minutes; then the ant collapsed, falling on one side. At this moment, the spiders approached and began to feed.”

The juvenile spiders are small enough that they can take a different approach. They actually climb onto their foe, deliver a bite to the abdomen, and then hang on to the ant’s back until it’s paralyzed so it can’t retaliate. Even at a young age, their venom is already something to be reckoned with. While the venom glands of an adult are more then 50 times bigger than a juvenile’s, the younger spider’s venom only takes a little bit longer to immobilize the prey. 

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Animals
7 Fun Facts for World Elephant Day
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Happy World Elephant Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.

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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.

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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit low-frequency sound, inaudible to humans, that warns other elephants. "It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told the Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.

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Human adults and babies often use pointing as a way to nonverbally get a message across, but not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 

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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.

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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.

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If you thought being pregnant for nine months was bad, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herds’ complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.

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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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Animals
Audible Launches 'Audible for Dogs' to Help Pet Parents Calm Their Stressed Canines
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In addition to a mutual love of hamburgers and lazy sunny afternoons in the backyard, dog owners can now share their affinity for audiobooks with their furry friends. As Fast Company reports, Audible has launched Audible for Dogs, a new service designed to keep canines relaxed while their owners are away from home.

Some people play music for lonely dogs, but according to an Audible press release, a 2015 academic study revealed that audiobooks worked better than tunes to calm stressed-out pets. To investigate the phenomenon further, Audible teamed up with Cesar Millan, the dog behaviorist who’s better known as the "Dog Whisperer." Their own research—which they conducted with 100 dogs, in partnership with Millan’s Dog Psychology Center in Santa Clarita, California—found that 76 percent of participating dog owners noticed that audiobooks helped their pets chill out.

Dog owners can play Cesar Millan’s new Guide to Audiobooks for Dogs—which is both written and narrated by Millan—for initiation purposes, along with a curated rotating selection of dog-focused audiobook titles including Trevor Noah’s Born a Crime: Stories from a South African Childhood, performed by Trevor Noah; Jane Austen’s Pride and Prejudice, performed by Rosamund Pike; and W. Bruce Cameron’s A Dog’s Purpose, performed by William Dufris. Each title features a special video introduction by Millan, in which he explains why the book is suited for doggy ears. (Pro tip: According to Audible’s research, dogs prefer narrators of the same gender as their primary owners, and books played at normal volume on an in-home listening device.)

Don’t have an Audible subscription, but want to see if your dog succumbs to the purportedly calming magic of audiobooks? New listeners can listen to one free Audible for Dogs selection with a 30-day membership trial.

[h/t Fast Company]

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