Seal turns tables on sharks to feast on their intestines
That shark’s fate is sealed. A seal has been spotted turning ecological roles upside-down by killing and eating blue sharks. If this turnabout proves common, ecologists might need to reassess the role of seals in marine ecosystems. Chris Fallows, a dive-boat operator in Cape Town, South Africa, was photographing 10 blue sharks underwater when a young male Cape fur seal arrived and chased and killed five of them, eating their intestines Ordinarily, seals and blue sharks, which are roughly the same size, both prey on much smaller fish, squid and other marine life. Several species of seal also feed on smaller sharks, and blue sharks have been seen pursuing though not catching fur seals. Fallows’s observations are the first time anyone has seen seals preying on such large sharks, says Hugues Benoit of the Canadian Department of Fisheries and Oceans in Moncton, New Brunswick. Benoit suspects this behaviour is more common than anyone realises. By chowing down on their competitors, seals could alter ocean food webs in unexpected ways, he says. If seals help hold down shark populations, for example, it could boost populations of smaller fish. If so, fisheries biologists may need to take that into account in managing fish populations.
Big bank balance begets brainy babies
Have Mum and Dad got a few quid to spare? You’d better hope so because the wealthier your parents, the larger the surface area of your brain, something that is linked with higher intelligence. We know that factors such as a parent’s job, education and income correlate with a child’s intelligence but the cause isn’t clear. A team led by Elizabeth Sowell at the Children’s Hospital Los Angeles used MRI scans to look at the brain structure of more than a thousand 3 to 20-year-olds. Parental income and education were both linked to their brain surface area. The size increase was largest in areas related to reading, language and spatial skills. The team then gave the children cognitive tests and found that, as expected, those from wealthier backgrounds did better. Statistical models given both sets of data suggested that brain surface area could partially account for the link between test performance and income. This is the largest study yet to connect socio-economic status and brain structure, but the mechanism that links them is unclear and the results do not suggest a child’s fate is cast in stone.
Spacecraft scorch marks fade away
We have been making a mess on Mars, but the Red Planet tidies up after us. A study of the scorch marks left by the Curiosity rover and Phoenix lander as they touched down on Mars has revealed that they fade over time. Ingrid Daubar of NASA’s Jet Propulsion Laboratory in California and her colleagues gathered images of the Curiosity and Phoenix landing sites taken by the Mars Reconnaissance Orbiter over a number of years. By measuring the relative amount of light reflected by the scorch marks and pristine soil in each picture, Dauber calculated that it should take 2.6 Earth years for them to disappear completely. That could be important for NASA’s next lander, the InSight mission, which will study heat flow on the planet’s surface. The work was presented at the Lunar and Planetary Science Conference in The Woodlands, Texas, last week.
Dusty tale of moon’s second tail
Did you know that the moon has a tail? Turns out, it has two. Data from NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE), which spent seven months orbiting the moon in 2013 and 2014, has revealed a tail of nanoscale dust particles. The finding follows the discovery of the first lunar tail in 1999, when ground-based telescopes spotted a faint stream of sodium gas stretching out behind the moon. Anthony Colaprete, who leads LADEE’s spectrometer instrument, thinks the second tail is the result of dust particles thrown up when asteroids crash into the surface and are pushed away by the sun’s radiation pressure.
Giant pandas are sociable after all
Everyone needs friends. Even giant pandas. Researchers spying on the species in the wild have found that they are more sociable than we thought, hanging out together for weeks at a time. We know very little about wild pandas because they are so rare and live in almost impenetrable forest. But in 2010 and 2011, Vanessa Hull of Michigan State University and her colleagues were given permission to attach GPS tracking collars to five pandas in the Wolong Nature Reserve in China. The collars transmitted each animal’s position every four hours, for up to two years. The team found that the home ranges of individual pandas overlapped and, on a few occasions, two animals spent several weeks in close proximity. “Sometimes the pandas were within 10 or 20 metres of each other, which suggests the pandas were in direct interaction,” Hull says. This happened in autumn, and pandas mate in spring, so it was probably not mating behaviour. The team also found that pandas rotated between several core areas, probably following patches of bamboo, their only food source. “They kind of eat their way out of the bamboo, and when it’s depleted they move on,” says Hull.
Charge of the magnetite brigade bugs power up on minerals
Is this the world’s smallest power station? Bacteria have been found growing on tiny magnetic particles, which they use as natural rechargeable batteries. Electric bacteria have become a hot topic, with the discovery that some bacteria found beneath seabeds and riverbeds can harvest energy in the shape of electrons gathered from tiny metallic particles. Bacteria can also dump electrons onto different metals. This cycle of harvesting and dumping electrons is essential for powering life, and in animals is done by eating food and breathing oxygen. Now James Byrne of the University of Tübingen in Germany and his team have found that tiny crystals of magnetite, a common magnetic mineral, can be used as both electron acceptors and electron donors for the bacteria, working like a battery. He grew mixed colonies of Geobacter and Rhodopseudomonas bacteria on magnetite and found that magnetite gave electrons to Rhodopseudomonas and accepted them from Geobacter (Science, doi.org/28f). In the wild, Byrne says, the two reactions probably happen during day and night cycles or tide phases, with each type of bacteria active at different times. The magnetite crystals, he says, act like rechargeable batteries. Lars Peter Nielsen of Aarhus University in Denmark says the discovery shows how magnetite can serve as a conductor, sink and source of electrons, depending on the needs of the microbes.
Dark matter’s a loner, galaxies say
Dark matter is so antisocial, it won’t even talk to itself. New measurements of collisions between dozens of galaxy clusters show that the mysterious stuff is even more ghostly than imagined. Dark matter is thought to make up 83 per cent of the matter in the universe, but scientists are unsure exactly what it is. Observations of collisions between galaxy clusters show that it refuses to interact with ordinary matter except through gravity: when two clusters collide, their galaxies glide past each other and leave a trail of gas behind. The dark matter, seen indirectly by its gravitational effects, remains with the galaxies. Some studies have hinted that dark matter might interact with itself via a new force. To test this idea, David Harvey of the Swiss Federal Institute of Technology in Lausanne and his colleagues looked at the positions of gas, galaxies and dark matter in 30 colliding clusters They found that the dark matter carries on its path unimpeded by any other dark matter around, suggesting that it doesn’t interact with itself after all.
Faulty genes can give us deadly flu
What makes the same flu virus kill some people, while others can just take a duvet day? A French girl has provided part of the answer. The girl nearly died of flu in 2011, aged only 2, but had none of the conditions that normally make the virus worse. Now partial sequencing of her and her parents’ genomes has revealed the role her genes played. We all have two copies of a gene that helps boost the production of interferon, a virus-fighting molecule. Each parent had one normal copy of the gene, but both had mutations in the other. Their daughter inherited a defective copy from each parent, leaving her immune and lung cells unable to crank out interferon when exposed to flu “This was her first case of flu ever, she had no immunity from previous infections,” says Jean-Laurent Casanova at the Imagine Institute of Genetic Diseases in Paris. “So the severity of the disease was all down to genetics.” The girl has been flu-free since being vaccinated. Casanova’s team is now looking for other mutations in interferon-related genes in children who have had severe flu.