It’s like having “an elephant stand on your thumb.”
That’s how deep-sea physiologist and ecologist Mackenzie Gerringer describes the pressure squeezing down on the deepest known living fish, some 8 kilometers down. What may help these small, pale Mariana snailfish survive elephantine squashing, says Gerringer of the University of Washington’s Friday Harbor Labs, is a body bulked up, especially at the rump, with a watery goo.
The snailfish family gets its nickname from the way some shallow-water species in thundering tides grip a rock with a little suction cup on the belly and curl up. “Quite cute,” Gerringer says, and maybe, if you squint, somewhat like a snail. She and colleagues discovered the deepest fish in 2014 in the western Pacific Ocean’s Mariana Trench and described the newly named Psuedoliparis swirei November 28 in Zootaxa. To catch specimens, Gerringer and colleagues turned to extreme trapping. They weighted a boxy, mesh-sided trap with steel plates to sink it. It took about four hours to fall to the bottom.
The scientists baited traps with mackerel, which snailfish don’t eat. But the fish do eat the underwater amphipods that mob a mackerel feast. Remotely related to harmless garden pill bugs, trench amphipods clean mackerel to the bones, Gerringer says. “I certainly wouldn’t swallow a live amphipod after seeing what they can do.” A snailfish, however, has a second set of jaws at the back of its throat that render crustaceans safe to swallow.
Story continues below image For animals that live in such extreme pressures and temperatures (1° or 2° Celsius), snailfish don’t “look very robust … or very armored,” she says. “You can actually see the brain through the skull.”
Skimping on dense muscles and bones may improve snailfish buoyancy and save energy. These fish also lack air pockets that give a little lift to some other fishes, but that would get squashed to nothing so far down. Instead, the snailfish have inner deposits of a watery goo, more buoyant than muscles and bones and less compressible than air.
The goo also may aid swimming efficiency by offering a cheap shape improvement, Gerringer and colleagues proposed December 6 in Royal Society Open Science. To test the idea, she 3-D printed and motorized a robo-snailfish. Easier than catching a real one, Gerringer says.
A latex sleeve around the robot tail let her add or subtract water as an approximation of the gelatinous tissue. With an empty sleeve, the wide fish body pinches in to a thin tail, inviting vortices that cause drag. With this abrupt narrowing, robo-swimming proved a struggle. Filling the tail-sleeve to create a tapering rear let the robo-snailfish swim faster.
This goo is cheap tissue to grow, Gerringer says. It’s mostly water, one thing a fish living underneath eight kilometers of ocean has in abundance.
OXON HILL, Md. — Fast radio bursts could come from a turbulent home. At least one source of these bright, brief blasts of radio energy may be a young neutron star assisted by a nearby massive black hole, new research suggests.
“The biggest mystery around fast radio bursts is how such powerful and short-duration bursts are emitted,” says astronomer Daniele Michilli of the University of Amsterdam. The latest observations, reported online January 10 in Nature and at a meeting of the American Astronomical Society, suggest the bursts are coming from an environment with an unusually strong magnetic field. That field leaves a signature mark on the radio waves, twisting them into spirals, Michilli and his colleagues report. Only a few fast radio bursts have ever been detected, and most appear as one-off events. Few known processes in the universe can explain them. But one burst, FRB 121102, has been seen repeating over the past decade or so (SN Online: 12/21/16). That repetition let astronomers follow up on the burst, and track it to a dwarf galaxy some 2.5 billion light-years away (SN: 2/4/17, p. 10).
Now, Michilli and his colleagues have used the Arecibo radio telescope in Puerto Rico to show that the burst’s source is embedded in an extremely strong magnetic field, 200 times stronger than the average magnetic field in the Milky Way.
The team measured the radio waves from 16 distinct bursts over three two-hour observational runs spanning several months. The bursts were exceptionally brief, the shortest lasting just 30 microseconds. That means that whatever emitted it must be just 10 kilometers wide, Michilli says.
“To emit a short burst you need a small region,” he says. “Therefore compact objects such as neutron stars are strongly favored by this result.” The team also analyzed the radio waves in a new way, revealing that what looked like individual bursts were actually composed of many smaller sub-bursts, says astronomer Andrew Seymour of the Universities Space Research Association at Arecibo. That complicates the picture even further. The sub-bursts might be intrinsic to the object that creates them, or they might be the result of the waves passing through blobs of plasma, he says.
Finally, the observations showed that the waves were polarized, all oriented in the same direction. But something had twisted the waves, forcing them to rotate in corkscrews on their way from the dwarf galaxy to Earth. Follow-up observations with the Green Bank Telescope in West Virginia confirmed the twists were really there.
Story continues below image The only phenomenon that is known to create such a rotation is a strong magnetic field, Michilli says. There are two main hypotheses for the bursts’ behavior. One is that they are from a young, energetic neutron star called a magnetar that’s sitting inside a shell of magnetized gas, which the magnetar itself expelled in a supernova explosion. The magnetar emits radio waves, and the shell makes them rotate.
“If you have young magnetars that have just been born in supernova explosions, only a few decades old, they could be very bursty objects, have very violent youths, and that could give rise to repeating fast radio bursts,” says astronomer Brian Metzger of Columbia University, who was not involved in the new study.
But Michilli points out that in order to drive such strong magnetic fields, the supernova remnant would have to be a million times brighter than even the brightest remnant in the Milky Way, the Crab nebula (SN: 1/1/11, p. 11). Instead, the bursts could come from a young neutron star orbiting the dwarf galaxy’s dominant black hole, which probably has between 10,000 and 1 million times the mass of the sun, he says.
Such large black holes are already known to have strong magnetic fields and to make polarized light rotate. And a neutron star nestling up next to a black hole is a plausible setup: There’s one orbiting the supermassive black hole at the center of the Milky Way. Although this neutron star’s radio waves don’t come in brief bright bursts, they are also twisted, the researchers say.
If not for that neutron star, “this would seem very contrived to me,” Metzger says. “That combines two unlikely things.”
More exotic explanations remain possible, too, Michilli’s team says.
“The joke is there are far more theories than there are observed bursts,” said coauthor Jason Hessels of the University of Amsterdam in a news conference January 10. “In the coming weeks we expect that very creative theorists will come up with explanations for our observations we haven’t thought of yet.”
Questions remain about whether all fast radio bursts, including the ones that don’t repeat, come from such exciting neighborhoods. “We cannot say yet if there are two classes with different properties, or if it’s one class of fast radio bursts and they just happen to be seen in different configurations,” Michilli says.
It’s also still unknown whether any other bursts have twisted waves at high frequencies — the smoking gun for strong magnetic fields. Measuring the rotation of the waves in FRB 121102 required hacking Arecibo with new hardware that let it detect higher frequencies than before. “We weren’t able to do that until recently,” Seymour says. “I stayed up on Christmas evening [2016] and made these observations, and luckily it paid off.” Maybe other fast radio bursts that Arecibo observed didn’t show the same rotation signature because the telescope wasn’t ready to measure it yet.
Hessels thinks “the prospects are quite good” for figuring out what fast radio bursts are in the near future. Several new radio observatories around the world are due to come online in the next few years. “These are going to be FRB factories,” Hessels said. He expects to find other repeating bursts, if they exist. “Then we can see if this repeating source is really a complete oddball, or part of a distribution of sources.”
Lab-grade flight tracking has gone wild, creating a broad new way of studying some of the flashiest of natural acrobats, wild hummingbirds.
One of the findings: Bigger hummingbird species don’t seem handicapped by their size when it comes to agility. A battleship may not be as maneuverable as a kayak, but in a study of 25 species, larger hummingbirds outdid smaller species at revving or braking while turning. Measurements revealed these species have more muscle capacity and their wings tended to be proportionately larger for their body size than smaller species. Those boosts could help explain how these species could be so agile despite their size, researchers report in the Feb. 9 Science. Adapting a high-speed camera array and real-time tracking software to perform in field conditions let the researchers analyze more than 200 wild birds swerving and pivoting naturally. With over 330,000 bird maneuvers recorded, the researchers could compare the agility of the different species. It’s the first comparative study of natural flight moves in wild birds, says coauthor Roslyn Dakin, who is based in Ottawa with the Smithsonian Conservation Biology Institute.
“What makes this research a clear advance is the methods they used,” says Christopher J. Clark of the University of California, Riverside. His hummingbird studies have revealed how the birds’ feathers squeal during flight (SN: 4/4/15, p. 5), but he was not involved in the new research.
In the experimental setup, four cameras film a temporary flight chamber in the field. Customized computer software allows the team to track birds in 3-D as they explore the space in any way they choose. The project began almost a decade ago when coauthor Paolo Segre adapted and then hauled the flight-tracking system to Ecuador, Costa Rica and Peru — great places to find hummingbirds with different wing shapes and body sizes, but hard on equipment. At the time, he needed five computers, sometimes running just on solar panels and a generator in the Amazon. “We were in a thatched hut,” accessible only by several hours’ boat ride, he says. “Monkeys poked their heads in.” Since then, computers have improved, and one machine is enough to run the software.
The new paper uses some of this hard-won data to focus on two kinds of turning maneuvers — a simple flying arc and a pitch-and-roll move that Dakin calls “turning on a dime.” That involves the bird slanting its body and then pivoting in place.
Birds’ agility did not appear to be affected in field sites at higher elevations. In theory, less oxygen and lower air pressure should make athletic flying tougher. An earlier study by the same researchers found that Anna’s hummingbirds (Calypte anna) accelerated more slowly and had other performance falloffs at altitudes higher than the birds’ home range. Yet birds that call those higher elevations home had adapted to the conditions.
Studying how hummingbirds, or even birds in general, maneuver has been hard to do. Previous approaches to understanding bird motion were limited to capturing data on animals performing set tasks. “A ballerina has a number of different moves,” Clark says, but “so far we’ve just studied individual moves.” Now researchers are starting “to put together the entire dance.”
Fossilized footprints from an iguana-like reptile provide what could be the earliest evidence of a lizard running on two legs.
The 29 exceptionally well-preserved lizard tracks, found in a slab of rock from an abandoned quarry in Hadong County, South Korea, include back feet with curved digits and front feet with a slightly longer third digit. The back footprints outnumber the front ones, and digit impressions are more pronounced than those of the balls of the feet. The lizard’s stride length also increases across the slab. That’s what you’d expect to see in a transition from moseying along on four legs to scampering on two, says Yuong-Nam Lee, a paleontologist at Seoul National University who first came across the slab back in 2004. A closer examination two years ago revealed the telltale tracks.
Lee and his colleagues attribute the tracks to a previously unknown lizard ichnospecies, that is a species defined solely by trace evidence of its existence, rather than bones or tissue. Lee and his colleagues have dubbed the possible perpetrator Sauripes hadongensis and linked it to an order that includes today’s iguanas and chameleons in the Feb. 15 Scientific Reports. Bipedal running certainly would have come in handy when escaping predatory pterosaurs some 110 million to 128 million years ago, the age of the rock slab. Lizard tracks are pretty rare in the fossil record, due to the reptiles’ lightweight bodies and penchant for habitats that don’t make great fossils. Though tracks appear in older fossils from the Triassic Epoch, 200 million to 250 million years ago, those prints belong to more primitive lizardlike reptiles. The new find edges out another set from the same region as the oldest true lizard tracks in the world by a few million years, the researchers say. Plenty of modern lizards use two legs to scurry around. Some studies have linked similarities in ancient lizard bone structure to bipedal locomotion, but it is unclear exactly when lizards developed bipedalism. Lee’s team argues that these tracks represent the earliest and only direct evidence of bipedal running in an ancient lizard.
Martin Lockley, a paleontologist at the University of Colorado Denver who studies ancient animal tracks, points to alternative explanations. S. hadongensis might have trampled over front prints with its back feet, obscuring them and giving the appearance of two-legged running. Preservation can vary between back and front footprints. And the stride lengths aren’t quite as long as what Lockley says he’d expect to see in running. “Running or ‘leaping’ lizards make for a good story, but I am skeptical based on the evidence,” he adds.
So it may take the discovery of more fossilized lizard prints to determine whether S. hadongensis’ tracks truly represent running on two legs rather than simply scurrying on four.
Free-roaming Przewalski’s horses of Central Asia are often called the last of the wild horses, the only living equines never domesticated. But a new genetic analysis of ancient horse bones suggests that these horses have a tamed ancestor after all, making them feral rather than wild.
The findings also debunk the idea that these domesticated ancestors — known as Botai horses —gave rise to all other modern horses. That leaves the progenitors of today’s domesticated horses a mystery, researchers report online February 22 in Science.
The earliest known domesticated horses were those of the ancient Botai people in northern Kazakhstan (SN: 3/28/09, p. 15). Botai sites dating to around 5,500 years ago are scattered with remnants of harnesses and pots with horse-milk residue, suggesting the animals provided both transportation and food.
To see how Botai horses relate to today’s steeds, evolutionary geneticist Ludovic Orlando of the Natural History Museum of Denmark in Copenhagen and colleagues analyzed DNA from 88 horses spanning the last 5,000 years or so across Europe and Asia. Horses from the last 4,000 years had less than 3 percent Botai ancestry, suggesting that different and unknown horses founded today’s populations. But Botai horses are direct ancestors of Przewalski’s horses, the study found.
Off the Kohala coast on the Big Island of Hawaii, Christine Gabriele spots whale 875. The familiar propeller scar on its left side and the shape of its dorsal fin are like a telltale fingerprint. Gabriele, a marine biologist with the Hawaii Marine Mammal Consortium, confirms the whale’s identity against her extensive photo catalog. Both Gabriele and this male humpback have migrated to this Pacific Island from Southeastern Alaska.
In those Alaska summer feeding grounds, Gabriele sees the same 300 or so whales “again and again.” But winter brings more than 10,000 whales to the waters of Hawaii from all over the North Pacific. Spotting 875 is like finding a needle in a haystack. Gabriele is here today to focus on the slew of worrisome bumps on the familiar traveler’s flank. The bumps are separate from the usual ones bulging from the head of a humpback ( Megaptera novaeangliae ). Those iconic oversize hair follicles are thought to be part of the sensory system. The smaller body bumps look more like bad acne or an allergic reaction. Noted on rare occasions in the 1970s, the condition called nodular dermatitis has become much more prevalent. These days, Gabriele and colleagues see these skin lesions on over 75 percent of Hawaii’s humpback visitors. The bumps coincide with other suggestions of declining health in the whales. In the nearly three decades that Gabriele has been studying whales, she would not describe the animals as skinny. Now, often “you can see their shoulder blades,” she says. “They look angular rather than round.” Gabriele’s team is trying to figure out the cause of the bumps, comparing tissue samples from bumpy and nonbumpy whales. Several times per week, a small team sets out on the water, research permits in hand. Once a whale pod is spotted, Gabriele’s colleague Suzanne Yin zooms in with a camera and volunteer Kim New enlarges the image on her iPad, examining skin on the whale’s flanks and behind the blowhole to confirm if it’s bumpy or not. Gabriele carefully steers the boat so that Yin can shoot a biopsy dart from a crossbow. The dart “takes a little plug of skin and blubber … about the size of a pencil eraser,” Gabriele says. The dart bounces off the whale and floats until the researchers can grab it. When darted, some whales dive; others show no reaction at all.
Collaborators from the National Institute of Standards and Technology’s Hollings Marine Laboratory in Charleston, S.C., are analyzing the skin for trace elements. National Marine Fisheries Service lab staff are studying the blubber for organic pollutants like PCBs and flame retardants. Preliminary results suggest that bumpy whales differ from nonbumpy in levels of manganese and a few other trace elements. Gabriele eagerly awaits the full analyses to make sense of what she’s seeing among the migratory creatures.
A chicken eggshell has a tricky job: It must protect a developing chick, but then ultimately let the chick break free. The secret to its success lies in its complex nanostructure — and how that structure changes as the egg incubates.
Chicken eggshells are about 95 percent calcium carbonate by mass. But they also contain hundreds of different kinds of proteins that influence how that calcium carbonate crystalizes. The interaction between the mineral crystals and the proteins yields an eggshell that’s initially crack-resistant, while making nanoscale adjustments over time that ultimately let a chick peck its way out, researchers report online March 30 in Science Advances. Researchers used a beam of ions to cut thin cross sections in chicken eggshells. They then analyzed the shells with electron microscopy and other high-resolution imaging techniques. The team found that proteins disrupt the crystallization of calcium carbonate, so that what seems at low resolution to be neatly aligned crystals is actually a more fragmented jumble. This misalignment can make materials more resilient: Instead of spreading unimpeded, a crack must zig and zag through scrambled crystals. Lab tests back up that finding: The researchers added a key shell-building protein called osteopontin to calcium carbonate to yield crystals like those seen in the eggshells. The presence of that protein makes calcium carbonate crystals form in a nanostructured pattern, rather than smooth and even crystal, study coauthor Marc McKee, a biomineralization researcher at McGill University in Montreal, and colleagues found.
The team also found structural variation on a minute scale throughout the eggshell, though it’s only about a third of a millimeter thick. Inner layers have less osteopontin, leading to bigger nanostructures. That may make the inner shell less resilient than the outer shell, which makes sense, McKee says. The outer shell needs to be hard enough to protect the chick, while the inner shell nourishes the developing chick.
Over time, the inner layers of the shell dissolve through a chemical reaction, releasing calcium to build a chick’s developing bones. The eggshell undergoes structural changes to facilitate that process, McKee and his colleagues found.
The researchers compared fertilized eggs incubated for 15 days to nonfertilized eggs. Over time, the nanostructures toward the inner shell became smaller in fertilized eggs, but remained the same in the nonfertilized eggs. The change gives the inside of the eggshell a bumpier texture, and by extension, more surface area. That provides more space for that shell-dissolving chemical reaction to take place, the researchers propose. The reaction also thins the shell overall, making it easier for a chick to break through from the inside when it’s time to hatch.
Advances in imaging technology are helping scientists find new details like this even in objects as familiar as a chicken eggshell, says Lara Estroff, a materials scientist at Cornell University who wasn’t part of the research. In connecting the eggshell’s functionality with its fine-grain structure, the new study could provide inspiration for designing new kinds of materials with specific properties.
Your brain might make new nerve cells well into old age.
Healthy people in their 70s have just as many young nerve cells, or neurons, in a memory-related part of the brain as do teenagers and young adults, researchers report in the April 5 Cell Stem Cell. The discovery suggests that the hippocampus keeps generating new neurons throughout a person’s life.
The finding contradicts a study published in March, which suggested that neurogenesis in the hippocampus stops in childhood (SN Online: 3/8/18). But the new research fits with a larger pile of evidence showing that adult human brains can, to some extent, make new neurons. While those studies indicate that the process tapers off over time, the new study proposes almost no decline at all. Understanding how healthy brains change over time is important for researchers untangling the ways that conditions like depression, stress and memory loss affect older brains.
When it comes to studying neurogenesis in humans, “the devil is in the details,” says Jonas Frisén, a neuroscientist at the Karolinska Institute in Stockholm who was not involved in the new research. Small differences in methodology — such as the way brains are preserved or how neurons are counted — can have a big impact on the results, which could explain the conflicting findings. The new paper “is the most rigorous study yet,” he says.
Researchers studied hippocampi from the autopsied brains of 17 men and 11 women ranging in age from 14 to 79. In contrast to past studies that have often relied on donations from patients without a detailed medical history, the researchers knew that none of the donors had a history of psychiatric illness or chronic illness. And none of the brains tested positive for drugs or alcohol, says Maura Boldrini, a psychiatrist at Columbia University. Boldrini and her colleagues also had access to whole hippocampi, rather than just a few slices, allowing the team to make more accurate estimates of the number of neurons, she says. To look for signs of neurogenesis, the researchers hunted for specific proteins produced by neurons at particular stages of development. Proteins such as GFAP and SOX2, for example, are made in abundance by stem cells that eventually turn into neurons, while newborn neurons make more of proteins such as Ki-67. In all of the brains, the researchers found evidence of newborn neurons in the dentate gyrus, the part of the hippocampus where neurons are born.
Although the number of neural stem cells was a bit lower in people in their 70s compared with people in their 20s, the older brains still had thousands of these cells. The number of young neurons in intermediate to advanced stages of development was the same across people of all ages.
Still, the healthy older brains did show some signs of decline. Researchers found less evidence for the formation of new blood vessels and fewer protein markers that signal neuroplasticity, or the brain’s ability to make new connections between neurons. But it’s too soon to say what these findings mean for brain function, Boldrini says. Studies on autopsied brains can look at structure but not activity.
Not all neuroscientists are convinced by the findings. “We don’t think that what they are identifying as young neurons actually are,” says Arturo Alvarez-Buylla of the University of California, San Francisco, who coauthored the recent paper that found no signs of neurogenesis in adult brains. In his study, some of the cells his team initially flagged as young neurons turned out to be mature cells upon further investigation.
But others say the new findings are sound. “They use very sophisticated methodology,” Frisén says, and control for factors that Alvarez-Buylla’s study didn’t, such as the type of preservative used on the brains.
Composting waste is heralded as being good for the environment. But it turns out that compost collected from homes and grocery stores is a previously unknown source of microplastic pollution, a new study April 4 in Science Advances reports.
This plastic gets spread over fields, where it may be eaten by worms and enter the food web, make its way into waterways or perhaps break down further and become airborne, says Christian Laforsch, an ecologist at the University of Bayreuth in Germany. Once the plastic is spread across fields, “we don’t know its fate,” he says. That fate and the effects of plastic pollution on land and in freshwater has received little research attention compared with marine plastic pollution, says ecologist Chelsea Rochman of the University of Toronto. Ocean microplastics have gained notoriety thanks in part to coverage of the floating hulk of debris called the great Pacific garbage patch (SN Online: 3/22/18).
But current evidence suggests that plastic pollution is as prevalent in land and freshwater ecosystems as it is in the oceans, where it’s found “from the equator to the poles,” says Rochman, author of a separate commentary on the state of plastic pollution research published in the April 6 Science. Plastic “is seen in the high Arctic, where we suspect it comes down in rain. We know it’s in drinking water, in our seafood and spread on our agricultural fields,” she says.
Laforsch and his colleagues looked at several different kinds of biowaste that’s composted and spread on farmland in Germany, including household compost and grass clippings, supermarket waste and grain silage leftover from biogas production.
Compost samples taken from supermarket waste contained the greatest amount of plastic particles, with 895 pieces larger than 1 millimeter found per kilogram of dry weight. Household compost in contrast contained 20 and 24 particles per kg of dry weight, depending on the size of the sieves used to sift the compost. The detritus included bits of polyester and a lot of styrene-based polymers, commonly used in food packaging. Almost no particles were found in samples of silage from biogas production. “I never thought about plastic in compost ending up as fertilizer. But when you think about it, it makes sense,” says environmental scientist Ad Ragas of Radboud University in Nijmegen, The Netherlands, who wasn’t involved in the work. A crate of rotting cucumbers wrapped in plastic that gets chucked, those stickers on every tomato in a bunch — that packaging doesn’t disappear.
Ragas says compost probably doesn’t contribute as much plastic to the environment as other sources, such as sewage treatment plant sludge, which contains polyester debris from clothes washers, and runoff from streets, which can be loaded with particles of synthetic rubber used in tires. But the compost contribution deserves investigation, Ragas says. “This triggers a lot of questions we haven’t studied yet.”
Those questions include possible effects on different organisms, from plants to earthworms to birds to people, Rochman says. Those effects will likely differ depending on the kind of plastic, which varies depending on its starting polymer and the additives used to impart certain qualities such as flexibility, sturdiness or durability under ultraviolet light.
“We are not saying we should get rid of all plastics,” Rochman says. “But we do need to start thinking of plastics as a persistent global pollutant.”
A hellishly unprecedented scene — what anthropologists suspect is the largest known child sacrifice — has been unearthed on a bluff overlooking Peru’s northern shoreline.
Around 550 years ago, members of the Chimú empire ritually killed and buried at least 140 children, ages 5 to 14, and 200 young llamas, says a team led by Gabriel Prieto of the National University of Trujillo in Peru and John Verano of Tulane University in New Orleans.
“There are no other examples of child sacrifices anywhere in the world that compare to the magnitude of this Chimú event,” Verano says. The discovery was announced April 26 by National Geographic in Washington, D.C. Except for a few incomplete skeletons, excavated children and llamas displayed cuts on their breast bones and dislocated ribs indicating that their chests had been sliced open. Three adults buried nearby on the bluff, including two women with violent head wounds, may have participated in the sacrifice.
Radiocarbon dating, mainly of ropes left around the llamas’ necks, puts the event at around 1450, shortly before the Inca conquered the Chimú in 1470.
A dried mud layer covering some of the sandy graves possibly resulted from flooding caused by massive rains. Agricultural crises triggered by repeated flooding might have led Chimú leaders to sacrifice children to their gods, Verano suggests.
