Bat-Eating Spiders Are Everywhere, Study Finds

There's only one place in the world to escape bat-catching spiders: Antarctica. These arachnids ensnare and pounce on bats everywhere else in the world, researchers say.

Bats rank among the most successful groups of mammals, with the more than 1,200 species of bats comprising about one-fifth of all mammal species. Other than owls, hawks and snakes, bats have few natural enemies.

Still, invertebrates — creatures without backbones — have been known to dine on bats. For instance, giant centipedes in a cave in Venezuela were seen killing and eating bats, and the arachnids known as whip spiders were spotted feeding on dead bats in caves of the Caribbean. Cockroaches have been observed feeding on bat pups that have fallen to the floor of caves.

Spider-eat-bat world

Accidental deaths of bats in spiderwebs were known as well, but were thought to happen very rarely. Still, spiders are known to occasionally dine on a variety of vertebrates — creatures with backbones. For instance, fishing spiders capture and devour fish and frogs; some species of wolf spiders, huntsman spiders, tarantulas and related spiders have been seen killing and eating frogs and lizards; and tarantulas and comb-footed spiders have apparently fed on snakes and mice. There are also numerous reports of spiders killing other flying vertebrates, snagging birds with large orb webs. 

Recent studies of a web-building spider species (Argiope savignyi) and a tarantula species (Poecilotheria rufilata) both killing small bats led researchers to suggest that bat captures and kills due to spiders might be more frequent than previously thought. So they analyzed 100 years' worth of scientific reports, interviews of bat and spider researchers and the staff of bat hospitals, and scans of image and video sites. The search revealed 52 cases of bat-catching spiders worldwide. [See Photos of Bat-Eating Spiders in Action]

Giant webs

Approximately 90 percent of known bat-catching spiders live in the warmer areas of the globe, in the third of the Earth surrounding the equator. About 40 percent live in the neotropics — the whole of South America, and the tropical regions of North America — while nearly a third live in Asia and more than a sixth live in Australia and Papua New Guinea.

Eighty-eight percent of the reported cases of bat catches were due to web-building spiders, with giant tropical orb-weaving spiders with a leg-span of 4 to 6 inches (10 to 15 centimeters) seen catching bats in huge, strong orb-webs up to 5 feet (1.5 meters) wide. 

In instances seen in Costa Rica and Panama, the spiders had built their webs near buildings inhabited by bat colonies. Bat-catching via spiderwebs was also witnessed particularly often in the parks and forests of the greater Hong Kong area. Future research may investigate whether the huge webs that sometimes block the entrances of tropical bat caves in east and southeast Asia and the neotropics may occasionally snag any members of the giant swarms of bats that emerge from the caves at night. [Photos: Creepy, Crawly & Incredible Spiders]

The other 12 percent of cases of spider kills of bats were from spiders that hunt without webs. For instance, tarantulas were seen eating small bats in tropical rainforests in Peru and eastern Ecuador and on the forest floor in northeastern Brazil. A reddish parachute tarantula (Poecilotheria rufilata) was also seen predating on a small bat in Kerala, India, while a huntsman spider (Heteropoda venatoria) was observed capturing and killing a small bat in a shed near Kolkata, India. An attempt by a large fishing spider (Dolomedes triton) to kill a bat pup was also witnessed below a bridge in Indiana.

The victims

Most bat prey of spiders are small or juvenile insect-eating bats, and usually are among the most common bat species of their areas. Bats entangled in webs were usually 4 to 9.5 inches (10 to 24 cm) in wingspan, including some of the smallest species of bats in the world, and they sometimes died of exhaustion, starvation, dehydration or overheating — but there were many cases where spiders were seen actively attacking, killing and eating these victims.

Bats are likely capable of detecting spiderwebs via echolocation, their biological sonar. Even if bats do collide with spiderwebs, only the strongest traps are likely capable of withstanding the energy of such an impact without breaking. As such, bat captures are likely rare.

Still, as scarce as spider captures of bats likely are, they would prove well worth the effort. The catch of a 2-gram bat by the giant orb-weaving spider Nephila pilipes, a common killer of bats, would be a bonanza about 10 times the mass of the average daily catch of insect prey, researchers noted.

Martin Nyffeler and Mirjam Knörnschild detailed their findings online March 13 in the journal PLOS ONE.

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Astronomy Teacher Finds Hubble Telescope's Hidden Treasure

A Connecticut astronomy teacher has uncovered a dazzling view of a satellite galaxy to the Milky Way while exploring the "hidden treasures" of the Hubble Space Telescope.

The new Hubble photo, released Thursday (Jan. 17), shows an intriguing star nursery dotted with dark dust lanes in the Large Magellanic Cloud about 200,000 light-years from Earth. The Hubble observation used to create the image was discovered in the telescope's archives by Josh Lake, a high school astronomy teacher at Pomfret School in Pomfret, Conn., as part of the "Hubble Hidden Treasures" contest that challenged space fans to find unseen images from the observatory.

Hubble officials also released an eye-popping video tour of the Large Magellanic Cloud, which zooms in on the region highlighted in Lake's photo.

Lake won first prize in the Hubble photo contest with an image of the LHA 120-N11 (N11) region of the Large Magellanic Cloud. Hubble officials combined Lake's image with more observations of the N11 region in blue, green and near-infrared light wavelengths to create the new view.

"In the center of this image, a dark finger of dust blots out much of the light," Hubble officials said in an image description. "While nebulae are mostly made of hydrogen, the simplest and most plentiful element in the universe, dust clouds are home to heavier and more complex elements, which go on to form rocky planets like the Earth." [Hubble Telescope's Hidden Treasures: Winning Photos

The interstellar dust in N11 is extremely fine, much more so than household dust on Earth. It is more similar to smoke, researchers explained.

The Large Magellanic Cloud, or LMC, is one of two small satellite galaxies of the Milky Way (the other is the smaller, aptly named Small Magellanic Cloud). Because of its relatively close proximity, the Large Magellanic Cloud has long been used as a sort of cosmic laboratory to study how stars form in other galaxies.

"It lies in a fortuitous location in the sky, far enough from the plane of the Milky Way that it is neither outshone by too many nearby stars, nor obscured by the dust in the Milky Way’s center," Hubble officials said in a statement. "It is also close enough to study in detail … and lies almost face-on, giving us a bird’s eye view."

In addition to the N11 region, the Large Magellanic Cloud is also home to the spectacular Tarantula nebula, the brightest nearby star nursery, Hubble officials said.

The Hubble Space Telescope has been snapping spectacular photos of the universe since 1994 and is a joint project by NASA and the European Space Agency. This month, NASA officials said the long-lived space observatory could potentially last through 2018.

You can follow SPACE.com Managing Editor Tariq Malik on Twitter @tariqjmalik. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

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'Universal' Personality Traits Are Not, Study Finds

Psychologists can get a pretty clear picture of someone's personality by evaluating to what degree they express traits known as the "Big Five" — openness, conscientiousness, extroversion, agreeableness and neuroticism. These factors are thought to be rooted in biology and to transcend cultural differences, but a new study of an indigenous Bolivian society shows the traits might not be universal after all.

Researchers spent two years studying more than 1,000 Tsimane forager-farmers, who live in isolated communities, each ranging from 30 to 500 people. Most are not formally educated, and they live in extended family clusters, sharing food and labor and limiting contact with outsiders.

The team first surveyed adults in the villages with a standard questionnaire (translated into the Tsimane language) that assesses the Big Five personality traits. Next the researchers asked Tsimane participants to evaluate their spouse's personality. This second part revealed that the subject's personality as reported by his or her spouse also did not fit with the Big Five traits. The researchers found that their results held true even when they controlled for education level, Spanish fluency, gender and age.

The team instead discovered evidence of a pair of broad traits that could be considered the Tsimane "Big Two." The researchers labeled one prosociality — socially beneficial behavior, which among the Tsimane, looks like a mix of items under the extroversion and agreeableness portions of the Big Five. The other trait is industriousness, which blends the efficiency, perseverance and thoroughness found in the conscientiousness portion of the Big Five, the researchers said.

The team says their results don't support the universality of the Big Five, and they speculated that the social structure of the Tsimane could have resulted in a trait structure different from the Big Five.

"Individuals in all human societies face similar goals of learning important productive skills, avoiding environmental dangers, cooperating and competing effectively in social encounters, and finding suitable mates. In small-scale societies, individuals have fewer choices for social or sexual partners and limited domains of opportunities for cultural success and proficiency. This may require abilities that link aspects of different traits, resulting in a trait structure other than the Big Five," the team wrote.

The research was detailed online in December in the Journal of Personality and Social Psychology.

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Weight Watchers works, scientific study finds

By Kate Kelland

LONDON | Thu Sep 8, 2011 10:29am EDT

LONDON (Reuters) - Overweight patients told by their doctors to go to Weight Watchers lose around twice as much weight as people receiving standard weight loss care over 12 months, according to the findings of a study published on Thursday.

In the first randomized controlled trial -- considered the gold standard of scientific analysis -- to directly compare a commercial weight-loss program with standard care by family doctors, Weight Watchers was found to be more than twice as effective.

More people stuck to the Weight Watchers diet, they lost more weight and fat mass, and also shaved more off their waist measurements than those assigned to standard care.

Susan Jebb of Britain's Medical Research Council (MRC) Human Nutrition Research Unit, who led the study, said the results showed Weight Watchers is "a robust intervention that is generalisable to other economically developed countries."

"This kind of research is important so that we can identify clinically effective interventions to treat obesity," she said.

The study, published in the Lancet medical journal, comes in the wake of research last month which said obesity is a global epidemic that is fast replacing tobacco as the single most important preventable cause of costly chronic diseases like heart disease, diabetes and cancer.

Worldwide, around 1.5 billion adults are overweight and another 0.5 billion are obese, with 170 million children classified as overweight or obese. Obesity takes up between 2 to 6 percent of healthcare costs in many countries.

In the weight loss study, which was funded by Weight Watchers International but run as an investigator-led trial with all data collection and analysis conducted by the independent research team, researchers assessed 772 overweight and obese adults in Australia, Germany and Britain.

Patients were randomly assigned to receive either 12 months of standard care as usually offered by the primary care team, or referred to and given a 12-month free membership for a Weight Watchers group in their neighborhood.

As well as losing twice as much weight as those in the standard care group, patients referred to Weight Watchers were also more than three times as likely to lose 10 percent or more of their initial body weight. Some 61 percent of patients in the Weight Watchers group lost at least 5 percent of their body weight, compared with 32 percent in the standard care group.

The average weight loss at 12 months was 5.1 kg (11.2 lbs) for those using Weight Watchers versus 2.2 kg for those on standard care. For those who completed the full 12 months, average weight loss was 6.7 kg on Weight Watchers versus 3.3 kg on standard care.

"These important findings show that obesity treatment is effective and structured commercial programs can enhance outcomes," said Nick Finer a consultant endocrinologist and bariatric physician at University College London Hospitals, who was not involved in the research.

In a commentary on the study, Kate Jolly and Paul Aveyard of the school of health and population sciences at Britain's Birmingham University said cost-effectiveness was a key factor in determining whether commercial programs like Weight Watchers become part of publicly funded health care.

They added that "the low cost of these programs -- at present about 50 to 60 pounds ($80 to $95) for 12 weeks -- makes the case for incorporation intuitively appealing."

David Kirchhoff, CEO of Weight Watchers International said the Lancet study "proves that Weight Watchers is part of the solution to help transform the health of nations."

"There is a clear need for practical treatment solutions that are proven effective, affordable and scalable to have a population-wide impact," he said in a statement.

(Reporting by Kate Kelland, editing by Paul Casciato)

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Hubble Telescope Finds Glowing 'Necklace' in Space (SPACE.com)

Talk about bling! A giant "necklace" glowing brightly in space is the centerpiece of a new photo from NASA's Hubble Space Telescope.

The cosmic object, which is appropriately named the Necklace Nebula, is a recently discovered planetary nebula, made up of the glowing remains of an ordinary, sun-like star. The Necklace Nebula is located about 15,000 light-years away in the constellation Sagitta.

Planetary nebulas form when stars similar to our sun deplete their store of hydrogen fuel. The stars' outer layers expand and cool, creating a massive envelope of dust and gas. Radiation flowing out from the dying star ionizes this envelope, causing it to glow. [See Hubble's photo of the Necklace Nebula]

Despite the implications of their name, planetary nebulas have nothing to do with planets. Rather, the term refers to their apparent resemblance to giant planets when they were observed through early telescopes.

The Necklace Nebula consists of a bright ring, measuring 12 trillion miles (more than 19 trillion kilometers) wide. The dense, luminescent knots of gas around the ring resemble the necklace's jewels. [50 Deep Space Nebula Photos]

A pair of stars orbiting close to one another produced this nebula, which is formally known as PN G054.2-03.4. About 10,000 years ago, one of the aging stars ballooned until it engulfed its companion star. The smaller star, though consumed, continued orbiting inside its larger companion, increasing the more massive star's rotation rate.

As a result, the bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force, most of the escaping gas seeped out along the star's equator, producing a ring. The embedded knots are densely packed clumps of gas in the ring.

The stars in the pair are so close — only a few million miles apart, they appear as one bright dot in the center of the ring. The stars are whirling so furiously around each other that they complete a full orbit in a little more than a day.

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Solar Storms Sparked By Giant 'Magnetic Rope,' Study Finds (SPACE.com)

A giant "magnetic rope" made up of twisting magnetic field lines could produce the strong electric currents that trigger solar storms, a new study finds.

Researchers at George Mason University sifted through data from NASA's Solar Dynamics Observatory (SDO) to study the magnetic rope phenomenon. Scientists have predicted that this rope is the cause of violent eruptions on the sun, but have previously struggled to prove its existence because of how quickly it moves.

Confirming the magnetic rope's existence would not only help astronomers understand the formation of solar storms, but would also be a key first step toward mitigating the adverse effects these eruptions can have on satellite communications on Earth. [Amazing New Sun Photos from Space]

Jie Zhang, an associate professor in the department of physics and astronomy at George Mason University, and graduate student Xin Cheng closely examined images taken by SDO's Atmospheric Imaging Assembly (AIA) telescope.

The researchers were able to pinpoint an area on the sun where a magnetic rope was forming. The AIA telescope captures images of the sun every 10 seconds, 24 hours a day.

"The magnetic rope triggers a solar eruption," Zhang said in a statement. "Scientists have been debating whether or not this magnetic rope exists before a solar eruption. I believe that the result of this excellent observation helps finally solve this controversial issue."

Powering solar storms

It is widely believed that magnetic fields in the sun play an essential role in storing energy and powering solar storms. Yet, the exact form that magnetic field lines take prior to eruptions is not well understood. Most field lines are semicircular loops with their foot-points rooted on the surface of the sun. As a result, they cannot erupt easily, and in fact, they often can prevent eruptions.

Scientists suspected that the magnetic rope, if it indeed exists, is the phenomenon that powers eruptions. A magnetic rope contains many magnetic field lines wrapping around a center axis and possibly twisting around each other.

Because of the twisting, a strong electric current can be carried by the magnetic rope. Theoretically, the electric current could produce enough electromagnetic force to overcome the overlying constraining force from other field lines and power the magnetic rope to move outward. [Photos: Sunspots on Earth's Star]

Images from the AIA telescope now reveal that, prior to eruption, there is a long and low-lying channel running through the entire active region, which heats to a scorching-hot temperature and slowly rises. When it reaches a critical point, it starts to erupt quickly.

This feature is distinctly different from the surrounding magnetic field lines, and the intensely hot channel is now believed to be the magnetic rope that scientists have been looking for.

More than just a pretty picture

Solar storms are violent eruptions on the sun that send a wave of charged particles, called plasma, into space at the speed of more than one million miles per hour. The cloud of plasma carries with it a strong magnetic field.

Sometimes these plasma clouds are directed at Earth, and can deposit a large amount of energy into the planet's magnetosphere.

Normally, the Earth's magnetosphere acts as a shield from these harmful particles and protects the environment. But a solar storm has the potential to disrupt the shielding effect, and severe space weather can have harmful effects on a wide array of technological systems, including satellite operations, communications, navigation and electric power grids.

Studies of space weather aid in the development of early warning systems for solar storms and help to minimize the damage from turbulent solar activity, researchers said.

"Understanding the eruption process of these storms will definitely help us better predict them," Zhang said. "We cannot prevent solar storms, just like we cannot prevent earthquakes or volcanoes. But the development of prediction capacity can help mitigate adverse effects. For instance, satellite operators can power-down key systems to prevent the possible damage to the systems."

The results of the study were reported at the American Astronomical Society Solar Physics Division Meeting, which is being held from June 12 to 16 at New Mexico State University in Las Cruces.

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