Gil Menda, Hoy Lab, Cornell University
Gil Menda, Hoy Lab, Cornell University

Jumping Spiders Can Hear Just Fine, Thank You Very Much

Gil Menda, Hoy Lab, Cornell University
Gil Menda, Hoy Lab, Cornell University

When Mother Nature closes a door, she opens a window, allowing each species to develop its own adaptations to make up for its deficits. Like jumping spiders: Scientists now say the tiny arachnids may have developed super-sensitive hearing to make up for their web-less lifestyle. A report on the spiders’ senses was published in the journal Current Biology.

Jumping spiders (family Salticidae) are big-eyed, fuzzy, and adorably small. The males of many species sport jewel-bright colors and engage in absurd exotic dancing to impress potential mates. Unlike most other spiders, jumping spiders don’t construct webs; instead, they stalk their teeny prey like teeny lions, then pounce.

Considering all this—plus the spiders’ lack of ears—scientists figured Salticidae species were mostly visual animals. Then researchers at Cornell University’s Hoy Lab stumbled onto some pretty compelling evidence to the contrary. They were researching jumping spiders’ visual processing abilities by hooking a single spider up to a brain activity monitor that made a popping noise each time the spider’s brain cells fired.

Co-author Paul Shamble recalls the day it happened. “[Researcher] Gil [Menda] was setting up one of these experiments and started recording from an area deeper in the brain than we usually focused on," he said in a statement. "As he moved away from the spider, his chair squeaked across the floor of the lab … and when Gil's chair squeaked, the neuron we were recording from started popping. He did it again, and the neuron fired again.”

Menda fetched Shamble to show him, and the two began talking about how spiders hear. “To demonstrate,” he said in the statement, “Paul clapped his hands close to the spider and the neuron fired, as expected. He then backed up a bit and clapped again, and again the neuron fired." Then they backed up again. And again. The neurons kept popping. The scientists were amazed.

Some real experiments were in order. First, they set spiders back up in the brain monitors and played a series of noises at various frequencies and distances. Next, they let the spiders roam around inside a mesh cage and videotaped their reactions to the same noises. Finally, they used a finely calibrated robot to vibrate a hair on the spider’s foreleg at the same frequencies while measuring the spider’s brain response.

The results of all three experiments agreed: The little spiders could hear just fine, even at distances of up to nearly 10 feet. They responded most strongly to low-frequency noises; when the scientists played the tone at 80 Hz, the spiders consistently froze in place like hunted animals. As it so happens, 80 Hz is also the frequency of the wingbeats of the predatory wasps and parasitic flies that prey on jumping spiders.

Previous studies have shown that freezing in place—part of the fight/flight/freeze survival response—may help animals focus their other senses and figure out what to do next. “All this might be particularly important … for species with vagabond lifestyles such as jumping spiders,” the authors write, “where the location of the threat and the subsequent route to safety may not be immediately apparent, instead requiring rapid and flexible decision-making.”

Stroking the spiders’ leg hairs also lit up acoustic pathways in their brains, which suggests that that’s how they’re taking in sound, even without eardrums.

The researchers say the spiders’ super-hearing may make up for their lack of webs, which serve as homes, safe spaces, defenses, and alarm systems for other spiders.

"In the movies, Spiderman [sic] has this strange, additional 'spidey sense' that helps him sense danger,” Menda said. “it turns out the real-life spidey sense of spiders might actually be hearing!”

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Why Tiny 'Hedgehog Highways' Are Popping Up Around London

Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]

Penn Vet Working Dog Center
Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.


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