Humpback whales use their flippers and bubble ‘nets’ to catch fish
Humpback whales need to eat
a lot every day, and some even use their flippers to help snag a big mouthful of fish.
Researchers filmed humpbacks
(Megaptera novaeangliae) hunting with
this tactic, called pectoral herding, off the Alaskan coast. It’s the first
time that this behavior has been documented in such detail, the team reports
October 16 in Royal Society Open Science.
Humpbacks often feed by
lunging with their mouths open to catch any fish in their path. Sometimes, the whales
will swim in an upward spiral and blow bubbles underwater, creating a circular “net” of bubbles
that makes it harder for fish to escape (SN:
10/20/15). “But there’s so much you can’t see while you’re looking at these
animals, standing on a boat,” says Madison Kosma, a whale biologist at the
University of Alaska Fairbanks.
The researchers got a better
view of the whales feeding at the ocean’s surface by flying a drone over the
water or extending a video camera attached to a pole from the walkways of
floating salmon hatcheries. Over the three-year study from 2016 to 2018, the
team noticed that two whales repeatedly consolidated fish inside bubble nets using
their two long, pectoral flippers.
In horizontal pectoral
herding, whales blew a bubble net before splashing a flipper at weak parts of
the net to reinforce the barrier. In vertical pectoral herding, whales created
a bubble net and then raised their flippers — like a referee
signaling a touchdown — as they ascended up through the net from deeper water, helping guide fish into their mouths. What’s more, the
whales sometimes tilted one or both of their flippers, reflecting sunlight off
the white skin on the underside to disorient fish, the researchers say.
This behavior isn’t just a
fluke, the scientists think. Although they observed the behavior in only a few whales feeding near salmon hatcheries (SN: 7/11/17),
Kosma speculates that other humpbacks also use their flippers in similar ways when
feeding.
Economics Nobel goes to poverty-fighting science
A scientific approach to reducing poverty’s many harmful
effects via field experiments in schools and other real-world settings has won the
Nobel Memorial Prize in Economic Sciences.
Economists Abhijit Banerjee and Esther Duflo, both of MIT, and Michael Kremer of Harvard University will receive equal shares of the prize of 9 million Swedish kronor, equivalent to about $900,000.
Duflo is only the second woman ever to be awarded the economics Nobel. The first was Elinor Ostrom, who won in 2009 for studies of how people in small communities manage shared natural resources. Ostrom died in 2012. Duflo, who will turn 47 on October 25, is also the youngest recipient of the prize.
“Poverty has deep roots, and we use an experimental approach to examine particular aspects of this problem and determine what interventions work,” Duflo said over the phone on October 14 at the Royal Swedish Academy of Sciences news conference in Stockholm announcing the prize.
More than 700 million people globally live in extreme poverty. Half of the world’s children leave school without basic language or math skills. Roughly 5 million children under age 5 annually die from diseases that could have been prevented with inexpensive treatments.
The three laureates design and test interventions aimed at specific ways to alleviate poverty’s effects in education, health care and other areas. Such studies are especially important because policies intended to fight poverty can often backfire (SN: 3/4/19).
Development economics, a branch of economics founded in the 1960s that studies how emerging, poor nations grow into more prosperous nations, seemed unable to make any theoretical headway by the late 1980s, says economist Jörn-Steffen Pischke of the London School of Economics.
Then, “the three [2019] laureates transformed development economics from a field that was stagnant and unattractive for young talent into one of the most vibrant areas of economics today,” Pischke says. That transformation began in the mid-1990s, when Kremer led a team that tested a range of interventions aimed at improving learning among students attending schools in western Kenya.
Banerjee and Duflo, often with Kremer, then performed
similar studies in other countries.
One important line of research developed “Teaching at the Right Level” programs, which enable teachers in low-income, developing nations to target instruction to students’ learning levels. Teachers in these programs learn ways to keep students from falling behind rather than forcing them through a one-size-fits-all curriculum for each grade.
A 2011 study led by Duflo, for instance, found that grade 1 test scores in a Kenyan school increased when teachers divided students into smaller classes based on their initial learning levels.
A string of studies in the same vein led by the 2019 laureates took randomized controlled trials and field experiments from outcast status to standard practice in development economics, says economist Tessa Bold of Stockholm University’s Institute for International Economic Studies.
Crucially, Bold says, those studies showed that the virtually unanswerable question “How can we fight global poverty?” could be broken into smaller, testable questions such as “Why do children not attend school?” and “Why do small-scale farmers not use technologies such as modern seeds and fertilizer that are known to be profitable?”
“The 2019 laureates’ research has had a huge impact on my own work,” Bold says.
How the second known interstellar visitor makes ‘Oumuamua seem even odder
The second space rock seen visiting our
solar system from another star is proving just how bizarre the first known
interstellar object, ‘Oumuamua, really was.
‘Oumuamua raised eyebrows when it appeared
in October 2017 looking more like a rocky asteroid than an
icy comet (SN: 10/27/17). Because
comets form farther from their host stars than asteroids, it should be easier
for comets to escape their star’s gravity to wander the galaxy. So astronomers
expect the vast majority of interstellar vagabonds to be icy bodies. But
‘Oumuamua didn’t sport the gaseous halo or tail that forms when sunlight
vaporizes a comet’s ice.
Now, new telescope images confirm that a
second interstellar object called 2I/Borisov (originally dubbed C/2019 Q4
(Borisov)) looks
like a garden-variety comet, researchers report online October 14 in Nature Astronomy. The cometlike
appearance of this object, first
glimpsed August 30, suggests that ‘Oumuamua’s weirdness was a
one-off, and that astronomers’ models of planetary systems are on the right
track (SN: 9/12/19).
Astronomers observed 2I/Borisov on two
nights in September with the William Herschel Telescope in the Spanish Canary
Islands and the Gemini North Telescope in Hawaii. Those images reveal that,
like comets native to our solar system, 2I/Borisov’s core is shrouded in a
gaseous halo trailed by a faint, broad stream of gas and dust.
“It’s kind of relieving that finally we
have something that meets our expectations,” says study coauthor Michał Drahus,
an astronomer at Jagiellonian University in Kraków, Poland. “Now we really can
be absolutely sure that ‘Oumuamua was one weird object.”
Whereas ‘Oumuamua vanished within weeks of
its discovery, astronomers have several months to take a closer look at
2I/Borisov. Higher-resolution telescope images may tease out the exact size and
shape of its core, and inspecting the specific wavelengths of light emanating
from the comet could help astronomers flesh out its chemical composition.
Preliminary wavelength observations have already hinted that 2I/Borisov contains cyanogen gas (made of carbon and nitrogen atoms), which is relatively common in comets native to the solar system. Astronomer Alan Fitzsimmons of Queen’s University Belfast in Northern Ireland and colleagues report these findings October 2 at arXiv.org.
An odd couple
The second known interstellar object, a comet currently cruising through our solar system called 2I/Borisov, looks fairly different from the first discovered interstellar visitor — an asteroid-like object called ‘Oumuamua that skirted by Earth in 2017. Here are some of the key distinctions between this pair of galaxy-trotting space rocks.
Differences between the first and second discovered interstellar objects
| ‘Oumuamua | 2I/Borisov | |
| Constellation of origin | Lyra | Cassiopeia |
| Halo and tail | No | Yes |
| Width | 400 meters | ~2 kilometers |
| Shape | Oblong | Unknown |
| Closest distance to Earth | 0.16 au (astronomical units) | 1.9 au |
| Closest approach to Earth | October 14, 2017 | December 28, 2019 |
| Time observable | Weeks | Months |
Sources: P. Guzik et al/Nature Astronomy 2019, ‘Oumuamua ISSI team/arXiv.org 2019, A.M. Hein et al/Acta Astronautica 2019
A supermassive black hole shredded a star and was caught in the act
Every so
often, a celestial slasher film plays out in the heavens, as a supermassive
black hole shreds a star and swallows part of it. Now scientists have gotten a
rare, early glimpse of the show.
The episode, described September 26 in the Astrophysical Journal, was first detected by telescopes in January and named ASASSN-19bt. It’s one of only dozens of these phenomena called tidal disruption events that astronomers have observed.
Such an event,
when a star passes close enough to a black hole to get sucked in and torn apart,
occurs only about once every 100,000 years in any given galaxy, says Suvi
Gezari, an astronomer at the University of Maryland in College Park, who was
not involved with the work. “This is really exciting,” she says.
The first
clues that scientists saw from ASASSN-19bt came from robotic telescopes that
had been searching the sky for supernovas, or violent explosions that mark the
death of massive stars (SN: 2/18/17).
When the telescopes instead caught a bright flare from the event, researchers turned
to other instruments to get a better look.
As it happened, that patch of sky was also being watched by NASA’s TESS satellite, which searches the sky for exoplanets (SN: 4/12/18), planets that orbit stars outside of Earth’s solar system. The TESS data, captured every 30 minutes, revealed the stellar material brightening as it began circling the black hole.
“We were able to see exactly when it started to get brighter,” says Thomas Holoien, an astronomer at the Carnegie Observatories in Pasadena, Calif. That’s the earliest observation of a tidal disruption event yet.
The energy
emitted by ASASSN-19bt, in a galaxy around 375 million light-years away from
Earth, was about 30 billion times the energy of our sun. A typical galaxy
contains around a billion or 10 billion stars, “so this was outshining every
other star in its galaxy,” Holoien says. If such an event happened in the Milky
Way, it would be so bright that it could probably be seen during the day.
As the star was drawn in by the black hole, it was pulled apart by the intense gravity of the black hole until eventually the star was stretched into a long strand of gas. Some of the shredded stellar guts were spit back into space. The rest looped around the black hole, crashing into itself and forming a spiraling ring of glowing, hot gas called an accretion disk.
The accretion
disk is like “water circling the drain of a bathtub,” says theoretical
astrophysicist Nicholas Stone of the Hebrew University of Jerusalem. Stone was
not involved with the work, but collaborates with one of the paper’s authors.
“It’s superheated, interstellar gas, but it still behaves like a fluid.”
More early
observations of tidal disruption events could help physicists improve estimates
of the masses of black holes and how quickly they spin, Stone says.
Such data also
could help answer how black holes form, and whether this type of star-shredding
activity plays into galaxy evolution, Holoien says. “This star died, but we’re
able to use its death to learn about the universe.”
Nearly 1,300 injuries and 29 deaths in the U.S. have been tied to vaping
Alaska is now the only U.S. state that
hasn’t reported vaping-related lung injuries. Nearly 1,300 people have been
sickened and 29 have died, including a 17-year-old from New York, the youngest
death yet. Even as the toll climbs, it may still take months before the
underlying causes of lung injuries, predominantly affecting many young and
otherwise healthy people, becomes clear, health officials said during a news conference
on October 11.
“I can’t stress enough the seriousness of these lung injuries,” said Anne Schuchat, principal deputy director of the U.S. Centers for Disease Control and Prevention in Atlanta. “We are not seeing a meaningful drop-off in new cases.” Along with the 49 states, cases have also been reported in Washington, D.C., and the U.S. Virgin Islands. The total number of cases — 1,299 as of October 8 — rose from 1,080 the previous week.
The majority still involve vaping products containing tetrahydrocannabinol — the psychoactive ingredient known as THC in marijuana. About three-fourths of the 573 patients for whom information was available reported using THC in their vapes three months prior to falling ill. About a third used only THC products, while others also used nicotine-containing products. About 13 percent exclusively vaped nicotine.
Rather than just one chemical or exposure, “I
think there will be multiple causes and
potentially more than one root cause” behind the injuries, Schuchat said,
adding she remained confident public health officials would find answers.
The U.S. Food and Drug Administration has collected more than 725 products from patients and has begun analyzing around 300, 79 containing nicotine and 225 containing THC. The dietary supplement vitamin E acetate, which may be toxic when inhaled (SN: 9/6/19), has been found in close to half of the THC products, said Mitch Zeller, director of FDA’s Center for Tobacco Products. The testing process is hampered by the fact that some of the products contain no liquid to analyze or very little, putting “an extreme limit on the number and types of tests that we’re able to perform,” he said.
On October 11, CDC also released
updated clinical guidelines to help doctors assess and care for these ill patients. In fall and
winter, as influenza and other respiratory infections become more common, it
may be difficult to determine whether lung injuries are exclusively related to
infection or vaping. The symptoms associated with the vaping-related lung
injuries, including shortness of breath, cough, chest pain and gastrointestinal
symptoms, can overlap with those seen with lung infections, and patients may
need to be treated for both.