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The Beetle That Doubles as a Mass Transit System

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In the tropical forests of Central and South America, a fantastic looking beetle begins its life in the drabbest of places. The harlequin beetle (Acrocinus longimanus) is named for the eye-catching splashes of black and red (or yellow) that cover its forewings. While seemingly conspicuous (some of the patterns look like something Guy Fieri would have on a bowling shirt), the designs actually help the beetles blend in with the mottled trunks and branches of trees, and it’s in the dull brown wood of fallen, decaying tree limbs that a mother harlequin beetle lays her eggs. She gnaws into the bark and deposits her eggs, usually in a batch of 15 to 20. The larvae dig deeper into the wood when they hatch, and again when they’re ready to pupate. Then they spend the next few months developing and growing into their adult form. 

Meanwhile, on those same rotting branches, the pseudoscorpion Cordylochernes scorpioides scuttles about eating small insects. Lacking the tails and poisonous stingers of their namesake, the true scorpions, these little teardrop-shaped arachnids instead take down their prey with venom secreted through their pinching claws. When a branch becomes too decayed to make a good home, or there are too many pseudoscorpions and not enough food to go around, some of these guys will have to find another dead limb to live on. But they’re tiny (often just a few millimeters long) and wingless, and the next branch might be far away. How do they get from Point A to Point B?

The answer is right underneath them. When the the fully-grown harlequin beetles chew their way back out from the branches, one of their first orders of business is to find a branch to eat bark and fungus from. Since both species are looking for the same thing, the pseudoscorpions hitch a ride on the beetles. 

After a beetle bores its way out of the wood, pseudoscorpions swarm around it and pinch its belly with their claws. Annoyed at the less than warm welcome to the outside world, the beetle flexes its abdomen and flicks its forewings, exposing its back and giving the pseudoscorpions space to climb aboard. 

As they shuffle onto the beetle, the male pseudoscorpions will make room for females, but shove each other around as they jockey for the best spots and try to keep other males from climbing on. When the beetle takes off, the pseudoscorpions secure themselves with “safety harnesses” they fashion from silk from their claws, and the males that managed to stay on the beetle compete for the attention of the female passengers and mate with them. The females usually disembark at the next branch, but the males may stay on the beetle if new females climb on and use the bug as a mobile love shack for a few days.

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Animals
Watch a School of Humpback Whales 'Fish' Using Nets Made of Bubbles 

Just like humans, humpback whales catch many fish at once by using nets—but instead of being woven from fibers, their nets are made of bubbles.

Unique to humpbacks, the behavior known as bubble-net feeding was recently captured in a dramatic drone video that was created by GoPro and spotted by Smithsonian. The footage features a school of whales swimming off Maskelyne Island in British Columbia, Canada, in pursuit of food. The whales dive down, and a large circle of bubbles forms on the water's surface. Then, the marine mammals burst into the air, like circus animals jumping through a ring, and appear to swallow their meal.

The video offers a phenomenal aerial view of the feeding whales, but it only captures part of the underwater ritual. It begins with the group's leader, who locates schools of fish and krill and homes in on them. Then, it spirals to the water's surface while expelling air from its blowhole. This action creates the bubble ring, which works like a net to contain the prey.

Another whale emits a loud "trumpeting feeding call," which may stun and frighten the fish into forming tighter schools. Then, the rest of the whales herd the fish upwards and burst forth from the water, their mouths open wide to receive the fruits of their labor.

Watch the intricate—and beautiful—feeding process below:

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Big Questions
Why Do Dogs Love to Dig?
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Dog owners with green thumbs beware: It's likely just a matter of time before Fido turns your azalea bed into a graveyard of forgotten chew toys. When dogs aren't digging up your prized garden, they can be found digging elsewhere in your yard, at the beach, and even between your couch cushions at home. But what exactly is behind your dog's drive to turn every soft surface he or she sees into an excavation site?

According to Dr. Emma Grigg, an animal behaviorist and co-author of The Science Behind a Happy Dog, this behavior is completely normal. "When people say 'why do dogs dig,' the first thing that always comes to mind is 'well, because they're dogs,'" she tells Mental Floss. The instinct first appeared in dogs' wolf ancestors, then it was amplified in certain breeds through artificial selection. That's why dogs that were bred to hunt rodents, like beagles and terriers, are especially compelled to dig in places where such animals might make their homes.

But this tendency isn't limited to just a few specific breeds. No matter their original roles, dogs of all breeds have been known to kick up some dirt on occasion. Beyond predatory urges, Dr. Grigg says there are two main reasons a dog may want to dig. The first is to cool off on a hot day. When stuck on an open lawn with little to no shade, unearthing a fresh layer of dirt untouched by the sun is a quick way to beat the heat.

The second reason is to stash away goodies. Imagine your dog gets bored with chewing his favorite bone but knows he wants to come back for it later. Instead of leaving it out in the open where anyone can snatch it up, he decides to bury it in a secret place where only he'll be able to find it. Whether or not he'll actually go back for it is a different story. "There's a disconnect with modern dogs: They know the burying part but they don't always know to dig it up," Dr. Grigg says.

Because digging is part of a dog's DNA, punishing your pet for doing so isn't super effective. But that doesn't mean you should stand idly by as your yard gets turned inside-out. When faced with this behavior in your own dog, one option is to redirect it. This can mean allowing him to dig in a designated corner of the yard while keeping other parts off-limits, or setting up a raised flowerbed or sandbox especially to satisfy that urge. "You can get him interested in the area by burying a couple bones or some interesting things in there for him to dig," Dr. Grigg says. "I like the idea of buried treasure."

If your dog's motive for digging is more destructive than practical, he may have an energy problem. Dogs require a certain amount of stimulation each day, and when their humans don't provide it for them they find their own ways to occupy themselves. Sometimes it's by chewing up shoes, toppling trash cans, or digging ditches the perfect size for twisting ankles. Fortunately, this is nothing more walks and playtime can't improve.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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