Soft robo-glove, an arachnid with three types of males, new UV images of Mars, and an edible transparent plastic alternative

Your hit of the best of last week’s science.

This arachnid has three different versions of male, but how?

Harvestmen are arachnids more closely related to scorpions than spiders, but they’re harmless – lacking venom and silk. They’re also “trimorphic”, with three types of males, and new research in the journal Behavioural Ecology is providing some clues as to how that happens.

Researchers looked at New Zealand’s Forsteropsalis pureora species where the alpha and beta males are large and use their big, protruding chelicerae (jaws) as weapons to fight each other for females. Gamma males are up to seven times smaller and, instead of fighting, search for undefended females to mate with.

A spindly-legged arachnid with its prey
A beta male harvestman with prey. Credit: Erin Powell

Harvestmen can shed legs to escape predators, but they never grow them back and the scars indicate whether it happened when they were a juvenile or an adult. The study found that males which lost at least one leg during their development were 45 times more likely to grow up to be the smaller, weaker, gamma males.

“Perhaps this is because they can’t get enough food for their development because their hunting is impeded,” says Dr Erin Powell, University of Auckland graduate, now a research scientist for the Florida Department of Agriculture and Consumer Services, US.

“Or maybe there’s no point in investing in big fighting weapons when they’re already disadvantaged when it comes to fighting. So, the arachnids’ resources may be invested in other things, such as testes size, sperm count, or aerobic poise, to ensure they make the most of the mating opportunities they get.”

A spider-like arachnid with long, spindly legs on a leaf
A gamma male with missing legs and prey. Credit: Erin Powell

Stunning new ultraviolet images of Mars

NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission has taken two new ultraviolet images of Mars, giving scientists insight into the Martian atmosphere and surface features.

MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) instrument obtained these global views of Mars in 2022 and 2023 when the planet was near opposite ends of its elliptical orbit.

Image of mars but coloured in green, purple, red, and blue
The first image was taken in July 2022 during the southern hemisphere’s summer season, which occurs when Mars passes closet to the Sun. The summer season is caused by the tilt of the planet’s rotational axis, similar to seasons on Earth. Argyre Basin, one of Mars’ deepest craters, appears at bottom left filled with atmospheric haze (depicted here as pale pink). The deep canyons of Valles Marineris appear at top left filled with clouds (colored tan in this image). The southern polar ice cap is visible at bottom in white, shrinking from the relative warmth of summer. Southern summer warming and dust storms drive water vapor to very high altitudes, explaining MAVEN’s discovery of enhanced hydrogen loss from Mars at this time of year. Credit: NASA/LASP/CU Boulder

The IUVS instrument measures wavelengths outside the visible spectrum. To make these wavelengths easier to interpret, the images are rendered with varying brightness levels of three ultraviolet wavelength ranges represented as red, green, and blue.

In this colour scheme, atmospheric ozone appears purple, clouds and hazes appear white or blue, and the surface can appear tan or green.

Image of mars, in greens, whites, and purples
The second image is of Mars’ northern hemisphere and was taken in January 2023 after Mars had passed the farthest point in its orbit from the Sun. The rapidly changing seasons in the north polar region cause an abundance of white clouds. The deep canyons of Valles Marineris can be seen in tan at lower left, along with many craters. Ozone, which appears magenta in this UV view, has built up during the northern winter’s chilly polar nights. It is then destroyed in northern spring by chemical reactions with water vapor, which is restricted to low altitudes of the atmosphere at this time of year. Credit: NASA/LASP/CU Boulder

An edible, transparent plastic-alternative thanks to bacteria

Scientists have developed an edible, transparent, and biodegradable material for use in food packaging. The material is made of bacterial cellulose (BC) which, unlike the cellulose found in the cell walls of plants, can be produced through microbial fermentation.

“This production method does not contribute to deforestation or habitat loss, making BC a more sustainable and environmentally friendly material alternative to plant cellulose,” says To Ngai, Professor at the Department of Chemistry, the Chinese University of Hong Kong.

Gloved fingers hold a small, transparent package filled with oil
By incorporating soy protein into the structure and coating it with an oil-resistant composite, the CUHK team successfully created an edible, transparent, and robust BC-based composite packaging. Credit: To Ngai

According to a recent paper in the Journal of the Science of Food and Agriculture, the team incorporated soy proteins into the structure, and coated it in an oil-resistant composite – to overcome BCs unfavourable sensitivity to moisture in the air.

The plastic alternative could be completely degraded within 1-2 months and according to Ngai “the material developed in this research is completely edible, making it safe for turtles and other sea animals to consume without causing aquatic toxicity in the ocean.”

Soft robo-glove could help stroke patients relearn to play music

Researchers have designed and tested a “smart hand exoskeleton” in the shape of a multi-layered, flexible 3D-printed robo-glove, which they say could help recovering stroke patients relearn to play music and other skills that require dexterity and coordination.

According to the new study in Frontiers in Robotics and AI, the glove incorporates integrated tactile sensors, soft actuators, and artificial intelligence.

“While wearing the glove, human users have control over the movement of each finger to a significant extent,” says senior author Dr Erik Engeberg, a Professor at Florida Atlantic University’s Department of Ocean & Mechanical Engineering, US.

“The glove is designed to assist and enhance natural hand movements, allowing them to control the flexion and extension of their fingers. The glove supplies hand guidance, providing support and amplifying dexterity.”

The robo-glove or smart hand exoskeleton in action. Credit: M Lin, R Paul, M Abd, J Jones, D Dieujuste, H Chim, E Engeberg

They then used machine learning to teach the glove to “feel” the difference between playing a correct versus incorrect version of a beginner’s song on the piano – Mary had a little lamb

“We found that the glove can learn to distinguish between correct and incorrect piano play. This means it could be a valuable tool for personalised rehabilitation of people who wish to relearn to play music,” says Engeberg.

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