News and Notes About Science
Posted June 11, 2018 6:46 p.m. EDT
How Often Does Lightning Strike? More Than Artists Figured.
Hungarian researchers have found that artists tend to paint lightning with fewer branches than the bursts of electricity actually have, according to a study published recently in Proceedings of the Royal Society A.
Their research points to how cultural legacies can distort our perceptions of natural phenomena, even those that we encounter with our own eyes.
Using a computer program, Gábor Horváth, head of the environmental optics laboratory at Eötvös Loránd University in Budapest, and his colleagues examined 100 paintings and 400 photographs of lightning. They found the pictures and paintings differed mainly in the number of root-like offshoots, which occur when charged particles try to carve the path of least resistance through air.
While painted lightning strikes had 11 arms at most, photographs showed lightning splitting into as many as 51 fingers. Actual numbers could be even higher, the authors noted, because some tendrils may be too dim for cameras to register.
In a follow-up experiment, the researchers asked 10 people to rapidly evaluate 1,800 photos each. They found that participants could accurately gauge up to 11 lightning branches. As the number of branches increased, people strongly underestimated the number of branches, with an exponentially growing gap between actual and perceived figures.
The finding is consistent with the ways humans are known to assess numbers, the authors noted. Below five, we’re able to subitize, or rapidly judge numbers of items without counting. Between six and 10, we count. Above 10, we estimate, with decreasing accuracy. This could explain why artists rarely portray lightning with more than 11 strands, Horváth said.
Simplified, zigzag images of lightning are also culturally ingrained (think of the lightning emoji or the common symbol for electricity). The imagery originated with ancient Greek and Roman depictions of Jupiter’s and Zeus’s thunderbolts, Horváth said.
While Horváth sees value in debunking “the scientific errors of well-known artworks,” not everyone believes art always needs to be scientifically accurate.
Lorraine Daston, director of the Max Planck Institute for the History of Science in Berlin, said that scientific accuracy and artistic goals of “what a painting should do” are moving targets.
Both “are constantly mutating through time,” she said.
— STEPH YIN
It’s Ladybugs Vs. Ladybugs (Until Aphids Arrive)
Aphids are a familiar sight in the garden, sucking the juices out of your rose bushes. Luckily, so are ladybugs, which prey on aphids and keep them in check.
But the relationship between predator and prey is more complex than you might think. Aphids may be important to the survival of some ladybug species we have come to know and love by warding off another predator that has been moving in and feasting on them.
The arrival about 30 years ago in the United States of the multicolored Asian lady beetle, or Harmonia axyridis, which gleefully devours other ladybugs’ larvae, led to a drop in numbers of the seven-spotted lady beetle. Although the seven-spotted beetle is also an invasive species, it has been around longer than the Asian lady beetle, and exists alongside native ladybug species, which also take a beating.
However, some aphids contain a substance that’s much more toxic to this aggressive invaderthan to the other ladybugs. As a result, researchers show in a paper in the Proceedings of the Royal Society B, these aphids may provide refuge to the other ladybug species by killing off their common enemy.
The aphids in the study, which are themselves invasive, are all from the same species and all look exactly the same. But some are toxic to the Asian lady beetle and others are not. Although researchers still don’t know what the toxic substance is, whether aphids have it or not seems to depend on what plants they’ve been eating, as well as their parentage, says Paul Lenhart, an entomology researcher at the University of Kentucky.
In a field Lenhart’s team put both toxic and nontoxic aphids on plants, and also added Asian lady beetlelarvae to some to see what would occur over the course of ten days. In the final reckoning, nontoxic aphids fared very poorly when the Asian lady beetleswere around, as did other ladybugs. But on plants with toxic aphids, there were not only more aphids, but other ladybug species were present in greater numbers.
“It’s kind of a refuge where there’s no Harmonia that’s going to eat them,” Lenhart said.
This suggests that there may be ways for prey to protect predators that are less damaging than the alternative. That may help explain why some native ladybug species have held on despite having many invasive species to compete with.
— VERONIQUE GREENWOOD
How Becoming Bird Food Helps Stick Insects Live On
It’s obvious why a stick insect’s wardrobe is the way it is. Look like a stick, avoid getting eaten.
But scientists in Japan noticed that despite their camouflage, stick insects became bird food quite frequently. And they also wondered: why do their eggs look like seeds?
In a paper published recently in the journal Ecology, the team of researchers suggest that these mostly flightless insects could sometimes benefit when they are eaten, using birds as carriers to disperse their eggs miles away, just like seeds. This passive dispersal mechanism could be why stick insects are found in places far from their original homes.
“It’s commonly assumed that when insects are eaten by birds, they and their unborn young have no chance of survival,” said Kenji Suetsugu, the leader of the study, a biologist who studies parasitic plants at Kobe University. But their results potentially overturn this dogma, he added.
Because plants can’t move around on their own, one way they disperse their seeds is by creating seed-containing fruits that animals eat. Thus, as animals travel, relieving themselves along the way, the plants travel too — through their seeds. But many birds also eat insects. So the researchers reasoned, that just like the fruits, the insects could be a means for dispersal, as long as their eggs can pass through the birds unharmed.
One thing that makes stick insect eggs different from most other insects is that they resemble seeds. And they’re coated in a chemical layer of calcium oxalate, the stuff humans find in kidney stones. As you might imagine, it doesn’t dissolve easily. Some of these eggs, carried inside females in certain stick insect species, also don’t need to be fertilized to hatch into viable offspring.
In 2015, Suetsugu and his team mixed dozens of these eggs into bird food and fed it to brown-eared bulbuls, birds that eat stick insects in Japan.
A small percentage of the eggs from three species of stick insects made it through intact. But two years later, none had hatched.
However, they repeated the experiment in 2017, with 70 eggs from a single species. Twenty percent made it through, and 14 of those hatched, proving that it was possible for birds that consumed stick insects to drop their eggs like seeds to new locations.
— JOANNA KLEIN
In the Depths of the Twilight Zone, an Escape Hatch
Some 200 to 500 feet below the ocean’s surface is the mesophotic zone, where ancient reefs once drowned, leaving behind empty bodies now inhabited by new corals and colorful mystery fish.
Those who study the zone have long needed a safer way to bring its fishy residents to the surface without killing them.
That’s why scientists at the California Academy of Sciences and the Monterey Bay Aquarium invented a device to safely transport fish, which was described in a paper published recently in the journal Frontiers in Marine Science.
It’s basically a portable decompression chamber, protecting fish from the same damage that humans experience when we dive deep into the ocean and return too quickly to the surface.
To really understand life in the twilight zone’s reefs, scientists need to collect living specimens.
Deep divers carry tiny bubbles of air in their bodies, and fish have swim bladders; both expand as bodies ascend and pressure decreases. And if care isn’t taken to decompress slowly along the way, bubbles expanding in the body can become fatal.
Some scientists poke holes into fish swim bladders with needles to solve the problem. But Bart Shepherd, who directs the Steinhart Aquarium at the California Academy of Sciences, with colleagues there and at the Monterey Bay Aquarium, thought there was a less intrusive way.
They developed transparent collection jars 2 feet long that fit into chambers, small and simple enough for divers to carry and manipulate.
Between 2014 and 2017, Shepherd and his colleagues journeyed to the Philippines, Vanuatu, Palau and Pohnpei to test the contraptions, collecting 174 fish from mesophotic depths as part of Hope for Reefs, an initiative to better understand and protect some of world’s least known coral habitats.
As the divers ascend with their catch, they insert the jar into the chamber and blow a bubble into it. This maintains the pressure until it reaches the surface. There, a valve releases air from the bubble over two or three days so the fish have time to adapt to surface pressure.
After decompression, the fish temporarily occupied makeshift kiddie-pool aquariums in hotel rooms before they were packed and shipped by air to California. Most survived the journey.
— JOANNA KLEIN
In Quebec, Warblers Gather to Set Record
Ian Davies got hooked on birds when he was 12. He went to a site near Plymouth, Massachusetts, where volunteers were putting bands on migrating birds.
“They let me release a Canada warbler,” he said, “and that was just game over.”
On May 28, he saw an estimated 700,000 warblers and set the birding world all atwitter with a posting on the site eBird describing the astonishing event: “Today was the greatest birding day of my life.”
He may one day top it, because he is 26. But he has a good deal of experience to look back on already. In 14 years of dedicated birding, he has been to 35 countries, and is a project coordinator of eBird, a citizen science project for gathering data from the worldwide community of birders, who contribute data on about 100 million sightings a year.
He and his fellow birders were at the Tadoussac bird observatory in Quebec, on the north bank of the St. Lawrence River. Pascal Côté, the director of the observatory who has been monitoring birds there for 10 years, said, “I have never seen anything like this.” His group, at a different location in the same area, saw 200,000 birds in what was only one part of a miles-wide corridor. He said he thought the total was probably closer to 500,000, but could be higher.
Davies’ method for counting was to calculate the rate of passage of birds across an imaginary line at different points through the day for a few seconds and extrapolate. Côté's team counted birds at their spot with a different approach, trying to tally the actual numbers, not one by one, but in blocks.
“As far as we’re aware,” Davies said, “it’s three times the number of warblers that anyone has ever seen at a location anywhere. It was basically a river of warblers. All heading southwest.” The previous record was 200,000.
— JAMES GORMAN