Watch a "Trained" Spider Named Kim Leap Six Times Its Body Length

iStock
iStock

Jumping spiders are cold-blooded assassins, masters of disguise, and just maybe a little quicker on the uptake than we're really OK with. For a study published in the journal Scientific Reports, a team of researchers from the University of Manchester "trained" one special jumping spider named Kim to leap in their experiment, all with the goal of demystifying the mechanics behind jumping spiders' abilities.

Kim was one of four regal jumping spiders (Phiddipus regius) the researchers brought into the lab for a close examination of how their bodies move as they leap and land. A jumping spider can clear up to six times its body length, which ranges from 0.04 to 0.98 inches—about the equivalent of a three-story building, relative to the spider's body size. For comparison, the farthest a human can jump is roughly 1.5 body lengths.

The researchers created an experiment chamber with platforms at varying distances from one another, then tried to coax the spiders into it. Only Kim would even enter. The researchers moved Kim between the take-off and landing platforms until she "became familiar with the challenge," they write. No tasty bait or stimulation (like blowing air) was used to motivate her. Still, her eventual familiarity with the task potentially implies some sort of learning. So even though she wasn't following orders, she figured out how to navigate the experiment's challenges—an impressive achievement for a spider about the size of an aspirin.

Using ultra-high-speed and high-resolution cameras, the researchers then filmed Kim's jumps to study how the arachnid moved her body when navigating a short jump equal to two body lengths; a longer jump equal to six lengths; and jumps between platforms placed at different heights. They found that Kim cleared shorter distances quickly and at low angles, thus sharpening her accuracy and boosting her chances of catching any prey that might be waiting at her destination. For longer jumps, she was more conservative with her energy, but her accuracy suffered.

Jumping spiders are excellent hunters, thanks in part to their precision ambushing skills. They also boast super-powered senses that help them locate their next meal before making their attack. Fine hairs on their legs allow them to "hear" subtle vibrations, and their eight eyes are sharp enough to track laser pointer lights.

This family of spiders also uses a hydraulic pressure system to move their legs. It helps jumping spiders extend their limbs, and some researchers have theorized that it also allows them to jump such great distances. According to the new study, that's not the case: "Our results suggest that whilst Kim can move her legs hydraulically, she does not need the additional power from hydraulics to achieve her extraordinary jumping performance," study co-author Bill Crowther said in a press statement. That means the jumps in the video below are made possible by Kim's muscle power alone.

Scientists Find Fossil of 150-Million-Year-Old Flesh-Eating Fish—Plus a Few of Its Prey

M. Ebert and T. Nohl
M. Ebert and T. Nohl

A fossil of an unusual piranha-like fish from the Late Jurassic period has been unearthed by scientists in southern Germany, Australian news outlet the ABC reports. Even more remarkable than the fossil’s age—150 million years old—is the fact that the limestone deposit also contains some of the fish’s victims.

Fish with chunks missing from their fins were found near the predator fish, which has been named Piranhamesodon pinnatomus. Aside from the predator’s razor-sharp teeth, though, it doesn’t look like your usual flesh-eating fish. It belonged to an extinct order of bony fish that lived at the time of the dinosaurs, and until now, scientists didn’t realize there was a species of bony fish that tore into its prey in such a way. This makes it the first flesh-eating bony fish on record, long predating the piranha. 

“Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time,” Dr. Martina Kölbl-Ebert, the paleontologist who found the fish with her husband, Martin Ebert, said in a statement. “Sharks have been able to bite out chunks of flesh, but throughout history bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later."

Kölbl-Ebert, the director of the Jura Museum in Eichstätt, Germany, says she was stunned to see the bony fish’s sharp teeth, comparing it to “finding a sheep with a snarl like a wolf.” This cunning disguise made the fish a fearful predator, and scientists believe the fish may have “exploited aggressive mimicry” to ambush unsuspecting fish.

The fossil was discovered in 2016 in southern Germany, but the find has only recently been described in the journal Current Biology. It was found at a quarry where other fossils, like those of the Archaeopteryx dinosaur, have been unearthed in the past.

[h/t the ABC]

Could Leonardo da Vinci's Artistic Genius Be Due to an Eye Condition?

Young John the Baptist, Leonardo da Vinci (1513-16, Louvre, Paris).
Young John the Baptist, Leonardo da Vinci (1513-16, Louvre, Paris).
Christopher Tyler, JAMA Ophthalmology (2018)

Leonardo da Vinci was indisputably a genius, but his singular artistic vision may have been the result of seeing the world differently in more ways than one. A new paper argues that he had strabismus, a vision disorder where the eyes are misaligned and don’t look toward the same place at the same time. This disorder, visual neuroscientist Christopher Tyler argues, may have helped the artist render three-dimensional images on flat canvas with an extra level of skill.

Tyler is a professor at City, University of London who has written a number of studies on optics and art. In this study, published in JAMA Ophthalmology, he examined six different artworks from the period when Leonardo was working, including Young John the Baptist, Vitruvian Man, and a self-portrait by the artist. He also analyzed pieces by other artists that are thought to have used Leonardo as a model, like Andrea del Verrocchio’s Young Warrior sculpture. Leonardo served as the lead assistant in the latter artist’s studio, and likely served as the model for several of his works. Leonardo was also a friend of Benedetto da Maiano, and possibly served as a model for his 1480 sculpture of John the Baptist. Tyler also looked at the recently auctioned Salvator Mundi, a painting that not all experts believe can be attributed to Leonardo. (However, at least one scientific team that examined the painting says it’s legit.)

With strabismus, a person’s eyes appear to point in different directions. Based on the eyes in Leonardo’s own portraits of himself and other artworks modeled after him, it seems likely that he had intermittent strabismus. When he relaxed his eyes, one of his eyes drifted outward, though he was likely able to align his eyes when he focused. The gaze in the portraits and sculptures seems to be misaligned, with the left eye consistently drifting outward at around the same angle.

'Vitruvian Man' with the subject's pupils highlighted
Vitruvian Man, Leonardo da Vinci (~1490, Accademia, Venice)
Christopher Tyler, JAMA Ophthalmology (2018)

“The weight of converging evidence suggests that [Leonardo] had intermittent exotropia—where an eye turns outwards—with a resulting ability to switch to monocular vision, using just one eye,” Tyler explained in a press release. “The condition is rather convenient for a painter, since viewing the world with one eye allows direct comparison with the flat image being drawn or painted.” This would have given him an assist in depicting depth accurately.

Leonardo isn’t the first famous artist whose vision researchers have wondered about. Some have speculated that Degas’s increasingly coarse pastel work in his later years may have been attributed to his degenerating eyes, as the rough edges would have appeared smoother to him because of his blurred vision. Others have suggested that Van Gogh’s “yellow period” and the vibrant colors of Starry Night may have been influenced by yellowing vision caused by his use of digitalis, a medicine he took for epilepsy.

We can never truly know whether a long-dead artist’s work was the result of visual issues or simply a unique artistic vision, but looking at their art through the lens of medicine provides a new way of understanding their process.

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