Something looking awfully like a moon was detected in the sky today
For 13 hours today, Earth had a new moon – or so we thought. Now astronomers have realised that an apparent small asteroid orbiting our planet is actually the European Space Agency's Gaia space telescope.
The International Astronomical Union's Minor Planet Centre (MPC) in Cambridge, Massachusetts, keeps records of all the tiny space rocks in the sky and publishes new observations from around the world. This morning, MPC's Gareth Williams posted a description of 2015 HP116, seemingly an asteroid about a metre across that was spotted in a geocentric orbit by the Pan-STARRS telescope in Maui, Hawaii, last week.
Williams's analysis of the orbit suggested the object would remain bound to the Earth-moon system between October 2014 and March 2019, making it a temporary moon of our planet. That's not without precedent – simulations suggest hundreds of tiny moons could be orbiting Earth. One, called 2006 RH120, was spotted in orbit before drifting off a year later.
Near miss
There's just one problem. It turns out this object is actually Gaia, the European Space Agency telescope currently mapping a million stars in the Milky Way. Just 13 hours after announcing the discovery of the new moon 2015 HP116, the MPC issued a retraction. "These things do exist, this just isn't one of them unfortunately," says Williams.
The mysterious, temporary moon has turned out to be the Gaia space telescope (Image: ESA, image by C.Carreau)
Earth's orbital neighbourhood is littered with all kinds of space junk, from defunct satellites to leftover rocket boosters, so the MPC runs a number of checks to filter out sightings of artificial objects, but this time they failed. "For some reason, it didn't show up in the checks," says Williams. But after posting the notice on the MPC website, he reran the calculations, and out popped Gaia. The object was dimmer in Pan-STARRS's observations than Gaia normally is, which could account for the confusion.
If the story sounds familiar, it's because we've been here before. In 2007, the MPC issued a warning that an object called 2007 VN84 was heading for a near-miss with Earth. It actually turned out to be ESA's Rosetta spacecraft on a fly-by past Earth, building up enough speed for its historic rendezvous with comet 67P/Churyumov-Gerasimenko, which occurred last year.
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If climate change was a game, we'd have racked up quite a score. A fresh study suggests that humans are responsible for a hefty number of today's extreme hot days and rainstorms.
Weather extremes, such as a Russian heatwave in 2010 and a drought in Texas in 2011, have been blamed on climate change before – but the attribution of individual events to it is still hotly debated.
So Erich Fischer and Reto Knutti at the Institute for Atmospheric and Climate Science in Zurich, Switzerland, took a bird's-eye view of how human activity is changing the planet. Using 25 different climate models, they calculated how the odds of unusual events – such as a 1-in-100 day temperature high or a 1-in-10,000 day rainfall event – have changed with the rise in global temperatures.
Their results show that global warming of 0.85 °C since the industrial revolution has had a powerful effect. Climate change is now responsible for 75 per cent of our extreme highs in temperature and 18 per cent of extreme rainfall, according to the data. The rarer a particular event, the more likely that warming is the cause, they say.
"A 1-in-10,000 day heat event is something that's only expected to happen every 30 years. But in a global-warming world, it's turned into a 4-in-10,000 day event. Three of those hot days – or 75 per cent – would never have happened if global warming wasn't around," says Fischer.
Tipping the balance
Even though warming isn't the only cause of extreme weather, it is increasingly tipping the scales in its favour, says Fischer. "Some people argue that these things have happened before," he says. "Well, yes, they have. But they had been far less frequent."
Fischer and Knutti also looked at what would happen if the climate warmed by 2 °C, a threshold that many scientists warn would be dangerous to exceed. In a 2 °C world, global warming would be responsible for four of every 10 extreme rainstorms, they find.
In a companion essay, Peter Stott at the Met Office Hadley Centre in Exeter, UK, suggests that this statistic should be a "sobering thought" for policy-makers looking to protect their cities and countries.
The numbers align with what climate scientists already suspected, says Francis Zwiers, a statistician at the University of Victoria in British Columbia, Canada. But they can help us when we wonder whether an unusually hot day is the result of global warming, or just chance.
"You can turn that question into an answer," he says. "We shouldn't be quite so surprised when what was formerly a once-in-a-20-year event occurs. We should be expecting it."
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Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world
Species: Torrent frog (Hylodes japi) Habitat: Near fast streams in the Atlantic forest of Serra do Japi in the State of São Paulo, Brazil
Stress can make it tough to get in the mood for sex, especially, if like torrent frog Hylodes japi, you live in constant fear for your life. But these frogs have found an ingenious way to procreate far away from the birds, snakes and other predators that lie in wait for a chance to devour some yummy frog meat. The male of this newly discovered species builds a secret underwater love chamber, where a pair can court, mate and lay eggs in peace and quiet.
Male torrent frogs like to hang out on the margins of fast streams, where they lure females with their serenades. If there's chemistry between them, they dive into a stream and the male takes his new partner on an underwater tour of favourite spots.
In the frog world, underwater love nests are unique to the hylodid family that includes H. japi. These frogs are shy and extremely secretive. So to catch them in action, Fábio P. de Sá from São Paulo State University in Brazil, and his team had to camouflage themselves carefully. So what did they find?
It takes an eager pair of frogs just 5 minutes to pick their ideal spot, out of several they check out. The male quickly carves out a chamber by excavating the sand around small rocks at the bottom of the stream. Then, like Christian Grey from Fifty Shades he invites his mate into his sex dungeon, which is only just big enough to fit the two amorous amphibians.
Afterwards, when the female has laid her eggs inside, they leave the chamber. The male holds onto the edges with his hands as he fights against the water flow. Then with her help he conceals the entrance with sand from the bottom of the stream, says de Sá.
"Hiding eggs inside an underwater chamber may increase protection of offspring against the strong water flow, predation, and potential cannibalism, since tadpoles are omnivorous," de Sá says.
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When there's no food to be found, cannibalism could be the last resort. This photo captures a rare instance of an iguana tucking into a juicy juvenile for lunch.
Last August, José M. Mora from the National University of Costa Rica and his team spotted the adult female preying on a 3-month-old of its own species at Santa Rosa National Park in north-western Costa Rica. The older lizard grabbed the victim with its mouth, while the young iguana fought back by biting its attacker's fingers.
(Image: Flávio H. G. Rodrigues)
The team suspects that the adult lizard resorted to cannibalism in response to a shortage of food caused by a drought in the area. The rainy season, which is typically in full swing at that time of year, was delayed by a recent El Niño event, reducing the amount of insects and plants – the basis of the iguanas' diet.
Although it is uncommon for reptiles to munch on their own kind, they have been caught in the act before. The small Greek island of Diavates, for example, is home to supersized wall lizards with a taste for the meat of younger specimens. And it may not be a recent trend: evidence suggests that some dinosaurs, in particular Tyrannosaurus rex, were cannibals.
Journal reference: Mesoamerican Herpetology, vol 2, p 107
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The prospect of genetically engineering humans has come a step closer, with the publication of the first paper to describe efforts to modify embryos. There is a long way to go before we can safely tinker with our genes, but at least one group in the US and four in China are aiming to edit human embryos: this will be the first of many studies.
The work was done using a gene editing technique called CRISPR (pronounced "crisper").
The idea of gene editing is to make specific changes in a particular gene, just as you might correct a spelling mistake. Gene editing has been around for decades, but in organisms other than mice it used to be difficult, expensive and time-consuming.
The CRISPR method – the name refers to characteristic sets of repeating chunks of DNA known as "clustered regularly interspaced short palindromic repeats" – developed in just the past few years, has changed all that, allowing biologists to achieve in weeks what used to take years.
The ease, speed and cheapness of CRISPR has made it possible for more people to experiment with gene editing. Last month, it was reported that a handful of teams are trying to modify human embryos using the method. Now one of those teams, led by Junjiu Huang at the Sun Yat-sen University in Guangzhou, China, has published its results.
Rejected eggs
"Because ethical concerns preclude studies of gene editing in normal embryos," the team writes, the researchers used human eggs that had been fertilised by two sperm rather than one.
These "polyspermic" eggs may develop for a few days but never develop normally and are discarded by fertility clinics.
Huang's team then attempted to modify one of the genes coding for the oxygen-carrying blood protein haemoglobin. Mutations in this gene cause the disease beta-thalassemia, itself a target for previous gene-editing attempts. The team injected the various snippets of RNA and DNA needed for CRISPR into the polyspermic eggs. One of the DNA sequences was a "template" for the desired changes to the gene, intended to guide the repair process.
Of the 86 eggs injected, just four were successfully modified – an efficiency rate far lower than required to make human germline gene editing a practical prospect. The others either did not survive, or were not successfully modified.
Missing the target
There were also changes to genes other than the globin gene. Such "off-target" alterations are a big concern, because they could cause serious illnesses.
It should be possible to reduce the number of off-target changes by refining the CRISPR method. However, it will probably never be possible to completely eliminate them. So if gene editing were ever to be used for modifying inherited human genetic material, it would be essential to check embryos for any off-target effects before implanting them in the mother-to-be.
In theory, this can be done by removing a single cell from a developing embryo and sequencing its DNA – a method already sometimes used during IVF to ensure embryos don't carry serious disease mutations, called preimplantation genetic diagnosis.
Living mosaics
However, Huang and his colleagues found what could be a serious problem: the embryos were a mixture of modified and unmodified cells – so-called genetic mosaics. That means the results of preimplantation genetic testing could be misleading.
On the face of it, these findings are not encouraging for those hoping to use gene editing to correct hereditary diseases in children. However it is too soon to draw sweeping conclusions. The low efficiency and the mosaicism could be a result of using flawed eggs. There might also be a specific problem with their approach – the paper was published just a day after being received by the journal, so it has not yet been thoroughly scrutinised by independent researchers. What's more, CRISPR is still a new method, so it is likely to be improved greatly in the coming years.
But should this kind of research be done at all? That depends on whether you think modifying the inheritable DNA of the human germline is acceptable. Some have called for a moratorium on this kind of work, and according to Huang, the paper was rejected by the journals Science and Nature in part because of ethical concerns.
Polls in various countries, however, indicate that there is actually substantial public support – sometimes over 50 per cent – for using germline modification to prevent genetic diseases.
The efficiency of gene editing can vary greatly across both species and cell types. So to find out whether any method is safe and effective it is necessary to try it in human embryos.
Journal reference: Protein Cell, DOI: 10.1007/s13238-015-0153-5
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Gene-editing has been used to remove faulty mitochondria in mouse egg cells, leaving mostly healthy ones to be passed to the next generation. The technique could be used to stop mothers from passing on some harmful diseases to their children.
It is the first time gene editing has been used to manipulate mammal mitochondria that can be inherited, says Juan Carlos Izpisua Belmonte of the Salk Institute for Biological Studies in La Jolla, California, who was part of the team that carried out the work.
The study follows the news that researchers in China have already begun testing genome editing techniques in human embryos, a scientific and ethical milestone that many are unhappy about. Belmonte's team is now gearing up to try its own technique on human eggs.
Powerhouse problems
Mitochondria are the cellular components that generate energy in our cells. They have their own set of DNA, which differs from that in the cell nucleus. Unlike nuclear DNA, which is inherited from both parents, mitochondrial DNA is passed down only from the mother via her egg.
Harmful mutations in mitochondrial DNA can cause a range of severe diseases for which there are currently no treatments. Earlier this year, this prompted the UK parliament to greenlight the donation of healthy mitochondria from someone other than the parents, essentially creating embryos with DNA from three parents.
Belmonte says his technique could offer a simpler alternative to such mitochondrial replacement therapy, which some believe carries genetic risks, while others are uncomfortable about the ethics of "three-parent" babies.
Shifting the balance
Belmonte's team worked with mouse egg cells that contain two different types of mitochondria, each with a different genome, a state known as heteroplasmy, which is a common phenomenon in mitochondrial disease.
They injected a short set of genetic instructions into each egg cell, which cut the DNA at a specific site in only one of the mitochondria types. These ones are then destroyed. This meant there was more of one of the types of mitochondria in the cell than the other. The technique is called TALENs.
Because most women at risk of passing on faulty mitochondria to their children carry some healthy and some mutated mitochondria, this technique offers a way to potentially increase the number of healthy mitochondria and lower the number of harmful mitochondria in their eggs.
A certain percentage of mutated mitochondria is needed to have a noticeable effect, so reducing the proportion of faulty DNA in this way may be enough to prevent disease in their child.
Harm reduction
To show that the technique could be used to prevent the inheritance of human disease, Belmonte's team created hybrid cells from mouse egg cells and cells taken from people carrying one of two serious disease mutations: one resulting in Leber's hereditary optic atrophy, which causes blindness, and the other causing nerve, balance and sight problems.
In both cases, they reduced the proportion of mitochondria carrying the harmful mutation in the hybrid. "Although our technique does not allow the total elimination of mutated mitochondrial DNA, we aim to reduce levels below the percentage needed for the disease to manifest," says Belmonte.
Ethical sticking point
"This study demonstrates that genome editing can be used in an animal to reduce the transmission of mitochondrial genes associated with certain diseases," says David Liu of Harvard University.
Because it involves simply injecting a genetic sequence into an egg cell, Belmonte believes this method is simpler than mitochondrial replacement therapy, which requires the nucleus of a fertilised egg cell to be removed and then transplanted to a donor egg cell.
The technique also avoids creating embryos that have genetic material from three parents. But the ethics of gene editing in human embryos is also hotly debated, with leading researchers calling for a moratorium on such research last month.
This hasn't stopped researchers pushing ahead. The first study testing these techniques in human embryos was published last week by a group in China. Only four of the 86 embryos edited were modified in the desired way and there was also a high number of unwanted mutations, possibly caused by the technique.
That work involved a different editing system, called CRISPR/Cas9, which is easier to use than the TALENs technique, but also causes more unintended mutations.
Not there yet
However, mitochondrial gene editing is not without risk, says Robert Lightowlers at Newcastle University, UK. For example, it remains unclear whether the numbers of lost mitochondria will have a long-term effect, he says, or whether cells will be able to compensate. And while the study found that TALENs editing seemed to target only the mitochondria, it could potentially be harmful if even a very low amount of the TALENs genetic instructions found their way into the cell's nuclear genome.
Next, Belmonte's team will collaborate with IVF clinics to test the method in unneeded human egg cells that have been donated for research by people with mitochondrial disease. But, he says, more basic research is needed before gene editing techniques can be used to create healthy embryos for parents with faulty mitochondria. "An open dialogue between scientists, physicians, legislators and society at large is urgently needed," he says.
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Strange and largely immobile organisms made of tubes were the first complex life on Earth. Appearing 579 million years ago, they thrived on the seafloor for some 37 million years, then vanished – becoming a curiosity we know only from faint impressions in the sandstone fossil record.
What made them die out? New fossil evidence from Namibia suggests that the Ediacarans, as these creatures are known, had their world turned upside by an explosion of life forms at the beginning of the Cambrian period 541 million years ago. Some of these may have evolved to eat their enigmatic predecessors and to bioengineer the environment in ways that left little hope for the passive Ediacarans.
If so, the very first mass extinction of complex life forms had a biological cause, unlike the big five mass extinctions which are thought to be environmentally driven – kicked off by widespread volcanic eruptions that poisoned the oceans or a massive meteorite strike, for example.
The disappearance of the Ediacarans from the fossil record has long troubled biologists. Leading theories are a catastrophic mass extinction, that Ediacarans got eaten or had their habitat destroyed by newly evolved animals, or no longer left fossils because of a change in ocean conditions.
No signature
But a careful search by Marc Laflamme of the University of Toronto in Mississauga and colleagues threw up no geochemical signatures of low-oxygen conditions or other turmoil to support the idea of an environmentally driven mass extinction. And given that soft-bodied Cambrian animals are fossilised within rocks like the famed Burgess Shale, it seems unlikely that the conditions simply didn't allow any surviving Edicaranas to leave a fossil trace in the Cambrian period.
That suggests that by the time the Cambrian explosion of species reached full force, the Ediacarans were gone, says Simon Darroch of the Smithsonian Institution in Washington DC. He will detail the team's evidence next week at the Joint Assembly of the American Geophysical Union in Montreal, Canada.
Their search took them to southern Namibia, where outcrops stretching over a large area expose fossils covering the crucial few million years when the Ediacarans disappeared and the new animals of the Cambrian appeared.
The deposits showed a vastly increased number of trace fossils from Cambrian animals, showing they had already evolved and were breaking up sediment and disturbing the Ediacaran environment.
Eco engineers
"Modern animals are ecosystem engineers. They alter the environment, burrow into sediments and prey on each other," says Darroch. So he looked for interactions between the two groups.
If these animals wiped out the Ediacarans, Darroch reasoned, fossils of the most recent Ediacaran communities should hint that they were struggling. By a number of measures, such as low species richness, he found the Namibian fossil communities did indeed "look very stressed". For example, he found traces in the latest Ediacaran fossils very similar to those left by sea anemones, which are predatory. "So there probably were predators in the late Ediacaran," he says.
All of this adds up to pretty robust evidence, he says, that the new species ate the old ones or destroyed their habitat.
However there was no cold, hard stop for everything Ediacaran, says Jim Gehling of the South Australian Museum in Adelaide, who has been studying Australian deposits of the same age.
"Clearly there was an extinction of the big fleshy things stuck on the seafloor," he says.
But he adds that although many of those Ediacarans were so strange that their biology makes little sense to us today, there is evidence that some of them did evolve movement and ways of ingesting food like modern animals, so may have given rise to life forms that evolved later.
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Bird flu is rampaging across the Midwestern US this week. So far 13 million chickens and turkeys have been culled or earmarked for destruction to stop the spread of H5N2, an offspring of Asia's H5N1 bird flu. Minnesota, the top US turkey producer, declared an agricultural emergency after announcing infected farms almost daily for two weeks. Iowa, the top egg producer, killed 3.8 million hens on one farm alone.
US agriculture officials hope the outbreaks will diminish as summer warmth and sunshine destroys flu viruses in the environment. But their bird flu problems may be only beginning. Wild ducks could infect the rest of the continent next autumn.
And while H5N2, unlike H5N1, seems to pose little threat to humans, the $45 billion US poultry industry is already suffering, as China, South Korea and Mexico ban US produce. Producers are calling for a poultry vaccine, and the US Department of Agriculture says it is developing one. But that might just make the problem worse by encouraging the spread of "silent" infections.
Running wild
The H5N2 virus story started last summer, when the H5N1 virus hybridised with others in wildfowl in Siberia to create a a new strain, H5N8. This reached the US, where it further hybridised to spawn the H5N2 that has now reached nine Midwestern US states and Ontario, Canada.
US Department of Agriculture chief veterinary officer John Clifford said last week that most of the early farms infected got the virus from the environment, not other farms, suggesting it was introduced by wild birds. If wild birds are carrying it, says Jeffrey Hall of the US National Wildlife Health Center in Madison, Wisconsin, "these viruses could persist and spread in northern hemisphere waterfowl populations for an extended period".
Ducks are now headed to North America's arctic nesting grounds.If they spread H5N2 there, southbound migrants next autumn could carry it into eastern North America. Three eastern states are among the top ten egg producers in the US, while seven produce nearly two-thirds of US chicken.
Vaccination trap
At the moment, an infected farm must kill all of its birds to stop H5N2. Poultry producers want a vaccine instead. Researchers at the US Department of Agriculture are starting tests, and Clifford says he is talking to vaccine companies.
But "vaccination will always be the last option for avian influenza," says Henry Wan of Mississippi State University, who discovered H5N1 in 1996. Widespread poultry vaccination in China, Indonesia and Egypt has not got rid of that strain.
On the contrary, vaccinated poultry spread the virus without getting sick, making its spread invisible. Vaccination has moreover driven the evolution of H5N1 as these viruses adapt to the vaccinated birds. China is now trapped, say researchers: it wants to give up expensive poultry vaccination, but if it did, ubiquitous, silent infections with H5N1 would decimate the unvaccinated birds.
Even if the US avoided this trap, vaccination would hurt its poultry exports, worth $3 billion a year. Tests cannot distinguish vaccinated from infected birds, so importers reject meat and eggs from countries that vaccinate their poultry.
Ruben Donis of the US Centers for Disease Control and Prevention calls relying on vaccines to control bird flu "unrealistic". It might be possible to use an H5N2 vaccine on some high-risk farms with careful monitoring for silent infections, he says. But "so far, there is no reason to believe that H5 could not be controlled through culling", plus sanitary precautions aimed at keeping environmental viruses out of henhouses.
Depending on when – and if – summer weather starts killing off stray viruses, and more effective sanitary measures kick in, that could mean millions more dead chickens and turkeys, even before the ducks fly south again next autumn.
Update, 28 April 2015:Since this article was first published on 27 April 2015, the number of birds culled in Iowa has changed and we've updated the article accordingly.
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WE PHYSICISTS have a habit of depicting our discipline as "beautiful" or "elegant", where an outsider might be forgiven for seeing no more than an endless morass of equations. In an ideal world, those equations would be unnecessary; the ultimate goal of physics – and science generally – is to describe the world as simply as possible.
One hundred years ago, one person brought us a great step closer. In this centenary year of general relativity, Albert Einstein is getting the plaudits, and no one would gainsay him that. But that same year, 1915, the excitement surrounding relativity spawned another seminal piece of work. Even among physicists, though, it is not nearly as famous as it should be. Perhaps that is down to the complexity of its mathematics, but perhaps the author's sex and sadly short life played their parts too. ...
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Video: Surreal X-ray movie reveals how a fly beats its wings
This surreal view inside the body of a blowfly is reminiscent of the imagery in the film Alien. Graham Taylor at the University of Oxford and colleagues used X-rays produced by a particle accelerator at the Paul Scherrer Institute in Switzerland to peer at the muscles of a live blowfly, in order to study how it beats its wings.
This video, which focuses on the fly's thorax, highlights the muscles that help it fly. The large muscles shown in red, orange and yellow provide the power that keeps the fly aloft, while the much smaller muscles shown in green, blue and cyan are used for steering. Each muscle contracts and relaxes in a single direction, but their collective motion creates a complex beat pattern that moves the fly's wings in three dimensions.
The mechanism may inspire engineers designing tiny mechanical devices. While conventional designs use clockwork, a collection of actuators that each bend and flex in only one direction – just like the fly's muscles – could achieve the same result more efficiently.
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ONE moment you're conscious, the next you're not. For the first time, researchers have switched off consciousness by electrically stimulating a single brain area.
Scientists have been probing individual regions of the brain for over a century, exploring their function by zapping them with electricity and temporarily putting them out of action. Despite this, they have never been able to turn off consciousness – until now.
Although only tested in one person, the discovery suggests that a single area – the claustrum – might be integral to combining disparate brain activity into a seamless package of thoughts, sensations and emotions. It takes us a step closer to answering a problem that has confounded scientists and philosophers for millennia – namely how our conscious awareness arises.
Many theories abound but most agree that consciousness has to involve the integration of activity from several brain networks, allowing us to perceive our surroundings as one single unifying experience rather than isolated sensory perceptions.
One proponent of this idea was Francis Crick, a pioneering neuroscientist who earlier in his career had identified the structure of DNA. Just days before he died in July 2004, Crick was working on a paper that suggested our consciousness needs something akin to an orchestra conductor to bind all of our different external and internal perceptions together.
With his colleague Christof Koch, at the Allen Institute for Brain Science in Seattle, he hypothesised that this conductor would need to rapidly integrate information across distinct regions of the brain and bind together information arriving at different times. For example, information about the smell and colour of a rose, its name, and a memory of its relevance, can be bound into one conscious experience of being handed a rose on Valentine's day.
The pair suggested that the claustrum – a thin, sheet-like structure that lies hidden deep inside the brain – is perfectly suited to this job (Philosophical Transactions of The Royal Society B, doi.org/djjw5m).
It now looks as if Crick and Koch were on to something. In a study published last week, Mohamad Koubeissi at the George Washington University in Washington DC and his colleagues describe how they managed to switch a woman's consciousness off and on by stimulating her claustrum. The woman has epilepsy so the team were using deep brain electrodes to record signals from different brain regions to work out where her seizures originate. One electrode was positioned next to the claustrum, an area that had never been stimulated before.
When the team zapped the area with high frequency electrical impulses, the woman lost consciousness. She stopped reading and stared blankly into space, she didn't respond to auditory or visual commands and her breathing slowed. As soon as the stimulation stopped, she immediately regained consciousness with no memory of the event. The same thing happened every time the area was stimulated during two days of experiments (Epilepsy and Behavior, doi.org/tgn).
To confirm that they were affecting the woman's consciousness rather than just her ability to speak or move, the team asked her to repeat the word "house" or snap her fingers before the stimulation began. If the stimulation was disrupting a brain region responsible for movement or language she would have stopped moving or talking almost immediately. Instead, she gradually spoke more quietly or moved less and less until she drifted into unconsciousness. Since there was no sign of epileptic brain activity during or after the stimulation, the team is sure that it wasn't a side effect of a seizure.
Koubeissi thinks that the results do indeed suggest that the claustrum plays a vital role in triggering conscious experience. "I would liken it to a car," he says. "A car on the road has many parts that facilitate its movement – the gas, the transmission, the engine – but there's only one spot where you turn the key and it all switches on and works together. So while consciousness is a complicated process created via many structures and networks – we may have found the key."
Awake but unconscious
Counter-intuitively, Koubeissi's team found that the woman's loss of consciousness was associated with increased synchrony of electrical activity, or brainwaves, in the frontal and parietal regions of the brain that participate in conscious awareness. Although different areas of the brain are thought to synchronise activity to bind different aspects of an experience together, too much synchronisation seems to be bad. The brain can't distinguish one aspect from another, stopping a cohesive experience emerging.
Since similar brainwaves occur during an epileptic seizure, Koubeissi's team now plans to investigate whether lower frequency stimulation of the claustrum could jolt them back to normal. It may even be worth trying for people in a minimally conscious state, he says. "Perhaps we could try to stimulate this region in an attempt to push them out of this state."
Anil Seth, who studies consciousness at the University of Sussex, UK, warns that we have to be cautious when interpreting behaviour from a single case study. The woman was missing part of her hippocampus, which was removed to treat her epilepsy, so she doesn't represent a "normal" brain, he says.
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Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world
Species: colonies of the genus Pyrosoma Habitat: open ocean in warm tropical and temperate waters
Ever feel that you're not that coordinated? Just imagine what life would be like if you were part of a giant colony of tiny individuals that all have to do the same thing at the same time.
Huge free-floating coalitions of marine invertebrates known as pyrosomes have to move together to ensure the colony can feed and move in the right direction. They lack any common nerves to communicate, so they may have a different way to move in time – light signalling.
Pyrosomes are made up of hundreds or thousands of clones called zooids. The entire brightly lit colony sprouts from a single individual, and the zooids mesh themselves together as the colony grows outwards in concentric circles from a closed tip to an ever-widening mouth. When the colony is small it looks rather like a butterfly net. As it lengthens, it becomes more like a giant worm that can reach the length of a sperm whale.
The zooids can reproduce by cloning, so the colony can regenerate injured parts and theoretically live forever, shrinking and growing based on available food and physical disturbance.
Huge but invisible
These giant glowing worms can't help but stand out. Yet pyrosomes remain an enigma. With so few people actually having seen them, when a video was posted on a major news site earlier this month saying it was showing pyrosomes, it took several days before anyone spotted that what had really been caught on camera was a mass of squid eggs.
The portraits of pyrosomes are fleshed out with anecdotes. Some divers say that swarms are as soft and delicate as feathers, whereas others claim they are tough enough to ensnare and drown unfortunate penguins.
Not so tough: A leatherback turtle munches on a pyrosome in the Azores (Image: Brian Skerry/National Geographic Magazine)
Why do we see so few of these amazing creatures? According to Mangesh Gauns of India's National Institute of Oceanography in Goa, it is not because pyrosomes are rare.
It is partly because they spend the day in the ocean depths and partly because we're not looking in the right places, he says. Go to the right areas and Gauns is confident that colonies would be abundant.
After analysing the water conditions off the coast of India where a swarm was found, he now thinks he knows what to look for: a combination of cyanobacteria that are small enough for the zooids to swallow along with the right mineral balance in the water. Gauns says these conditions should be commonplace far enough from coastal waters, which are dominated by larger plankton that can block the filter-feeding system of the pyrosomes.
"I am excited to see if we can use these results to get this organism studied more openly," he says.
Light signals
The movement and feeding of the colony is a joint effort and the whole pyrosome is like a giant filtration system. Each zooid sucks in water from outside the colony and blows it out again the other side. This not only feeds them but creates a rudimentary jet engine to give them some control over where they drift to.
Shutting off this propulsion system allows the colony to sink out of harm's way – they regularly dive down to 500-700 metres and have been collected from as far down as 3000 metres. But because they are made up of so many small zooids, coordinating their actions isn't easy. Unpublished research from David Bennett then at Bangor University, UK, offers tentative evidence that this is where a pyrosome's impressive light show comes in.
When a pyrosome is brushed by an external object, it lights up like a Christmas tree – in red or white depending on the species. The signal ripples through the individuals, and they respond by cutting off their engines. Just think of a second world war U-boat film. When the red lights start flashing, it's time to dive.
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What if we transformed carbon dioxide from being a waste product into being a huge battery to help even out our energy supply? We could make carbon storage pay off, while solving problems of intermittent energy supply from renewables.
So say Tom Buscheck from the Lawrence Livermore National Laboratory in California and his colleagues who presented a design for this type of energy storage at the European Geosciences Union general assembly last week in Vienna, Austria.
Their design would be able to store the excess energy produced by renewable and conventional power sources when demand is low and, at the same time, lock up the major cause of global warming – carbon dioxide.
Carbon capture and storage has been slow to develop, in part because it is an extra cost for energy producers that provides little direct pay-off. "There's no business case to do it," says Jim Underschultz from the University of Queensland in Australia.
"CCS hasn't been utilised because no one has come up with a viable use for that storage," says Buscheck. But if stored CO2 could be used to hold surplus energy, it may give such technology the economic boost it needs.
"The only way you can decarbonise the fossil-fuel energy systems is if you can devise an approach where the economics makes sense," says Buscheck, who thinks their design, which is funded by the Geothermal Technologies Office at the US Department of Energy, does just that.
Supercritical storage
Buscheck's team proposes storing that excess energy in two forms: pressure and heat. Excess electricity would power a pump that injects supercritical CO2 – a hybrid state of liquid and gas – into underground brine in sedimentary rocks between 1 and 5 kilometres below the surface. Supercritical CO2 can drive turbines much more efficiently than steam and can take a lot of squeezing and heating – improving its capacity to store energy.
Another set of pipes tap into the brine in the sedimentary rocks. As the CO2 is pumped in, it will displace some brine, which is collected at the surface. Surplus energy can also be used to heat the brine and circulate it down into the deep rocks, which are able to store the heat effectively.
When the heated brine comes into contact with the CO2, it causes it to expand, thereby increasing the pressure of the stored CO2. The heat energy can be gathered by allowing the CO2 to depressurise, spinning supercritical CO2 turbines, which are 50 per cent more efficient than the steam equivalent. The team's modelling suggests that the system could regather up to 96 per cent of the heat stored.
Their approach could help solve a major problem with renewables: intermittent power. Solar and wind can fail to produce power when there is high demand. Similarly, sometimes they produce plenty of energy when demand is lower, and in this case, sources like nuclear, coal and older gas power stations can produce energy at a loss, or simply waste the heat they produce, never turning it into electricity.
The massive batteries that would be required to store the excess are still expensive and not very effective. Storing the energy by using it to pump water uphill – a current state of the art – can also waste a quarter of the energy in the process.
Getting bigger and better
"There is no doubt in my mind that we need to consider hybrid technologies of the sort proposed here," says Peter Cook from the University of Melbourne, Australia. He says the proposal takes a lot of existing ideas and integrates them in a new way, meaning that most of the technology is already proven.
But while this could contribute to reducing atmospheric carbon dioxide, it is unlikely to become a major carbon sink, says Cook.
One site could only store about 8 million tonnes of CO2 each year for 30 years – about the same amount as produced in one big coal-fired power station, says Buscheck, whose group is now looking for power companies to partner with on a pilot project.
Whether it is possible to scale-up the design remains to be seen, say Cook and Undershultz. Given its complexity, Undershultz says that costs and inefficiencies could add up as they scale it up. And Stuart Haszeldine from the University of Edinburgh, UK, says it would require a really good knowledge of geology to ensure carbon is sealed and does not escape.
Correction 21 April 2015:When this article was first published on 20 April 2015, the depth at which supercritical CO2 would be stored was wrong. This has now been corrected.
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Video: Wild chimps take care before crossing the road
Screech! Bang! It's the sound we all dread when crossing busy roads. Now, it turns out that like us, wild chimpanzees learn to respect roads, adopting the same cautious drills as humans, including looking both ways to check for traffic.
Hopefully, by studying how chimpanzees cope with roads, we can find ways to make them safer for wildlife, especially since road-building in Africa is on the increase.
In a 29-month survey, researchers observed and recorded 20 instances of wild chimps crossing a busy road in Sebitoli, in the northern part of Uganda's Kibale National Park. They watched 122 chimps cross the highway used by 90 vehicles an hour, many speeding at 70 to 100 kilometres an hour.
It's the first report on how chimpanzees behave crossing a very busy asphalt road, says Marie Cibot of the National Museum of Natural History in Paris. "We've described chimpanzee behaviour facing a dangerous situation never described before," she says, pointing out that earlier studies looked at narrower, unpaved and less busy roads.
Extra vigilance
Chimps are exceptionally cautious when they cross the road. Ninety-two per cent of them looked right, left, or both ways before or during crossing, and 57 per cent ran across – showing that they knew the value of reaching the other side as quickly as possible.
Alpha males led and organised 83 per cent of the road-crossing posses, compared with only 51 per cent of tree-climbing expeditions in the forest studied in parallel. This implies that they recognised the importance of extra vigilance during road crossings.
There was also evidence that healthy and dominant chimps often made sure that stragglers or more vulnerable members of the group crossed safely. Some 86 per cent of the healthy chimps looked back or stopped when at least one vulnerable individual, such as an infant or injured chimp, trailed behind.
Chimps behaved differently crossing a quiet road in an earlier study in Bossou, Guinea, led by Kimberley Hockings of the Centre for Research in Anthropology in Lisbon, Portugal.
"At Sebitoli, chimpanzees tended to split into smaller subgroups when crossing, whereas chimpanzees at Bossou often, but not always, crossed in progression lines," says Hockings. "This might be down to a higher intensity and speed of traffic at Sebitoli, forcing chimpanzees to split up."
Cibot now hopes to work with the Ugandan authorities to test new safety measures. "We aim to test mitigation measures such as bridges, underpasses, reduced speed limits, speed-bumps and police patrols in the area," she says. "Road infrastructure is spreading throughout Africa to support regional development, industry and tourism, and studying chimpanzee adaptation facing roads represents a way to reduce the risk of collisions."
Journal reference: : American Journal of Primatology, DOI: 10.1002/ajp.22417
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The number of nests of Kemp's ridley turtles dropped massively in 2010, when the Deepwater Horizon oil spill happened (Image: Erich Schlegel/Corbis)
There's something amiss with iconic marine animals in the Gulf of Mexico: sea-turtle populations are in retreat, dolphins are in poor shape and whales are avoiding their usual hunting grounds.
Such long-term effects seem to linger five years on from the largest oil spill in US history, which followed the explosion of the Deepwater Horizon rig on 20 April 2010, killing 11 workers and wreaking havoc on the region's wildlife.
Following the spill in the north of the Gulf of Mexico, there was a reverse in a sustained two-decade recovery of the world's most endangered sea turtle – the Kemp's ridley, which neared extinction in the 1980s.
To what extent the oil disaster is to blame is still under debate, but the matter is shrouded in mystery partly because ongoing litigation over compensation means that few scientists are prepared to discuss their data publicly.
The answer is important because, like other iconic and long-lived marine animals such as sperm whales and dolphins (see box, below), sea turtles are at or near the top of the food chain. What happens to them is therefore a bellwether for potential impacts of the spill on the rest of the marine ecosystem.
Changing fortunes
Most Kemp's ridleys lay their eggs on beaches in the Tamaulipas region of north-eastern Mexico. A joint Mexican and US conservation programme launched in 1978 had put the turtles on the route to recovery: the number of nests rose by 15 per cent per year on average, from a record low of 702 in 1985 to 21,000 in 2009, with growth accelerating to 19 per cent in the late 2000s.
Then, in 2010, it all started to unravel (see graphic, above). "Suddenly, the number of nests counted at the primary nesting beaches plummeted by nearly 40 per cent," says Selina Heppell of Oregon State University in Corvallis. Although nest numbers rose back up to 2009 levels in 2011 and 2012, they did not resume the increasing trajectory. "Now, the number of nests is declining, with 2014 showing the lowest number since 2006," says Heppell.
Was the 2010 collapse and slowdown in recovery caused by the spill, or was it a coincidence driven by other factors?
Kimberly Reich and her colleagues at Texas A&M University in Galveston presented data at a February meeting in Houston, Texas, showing that the turtles stopped foraging on the seabed in areas contaminated by oil. But there's no proof that this affected survival and precipitated the collapse of nesting numbers.
Benny Gallaway, president of LGL Ecological Research Associates in Bryan, Texas, and a consultant who has previously helped compile stock reports on Kemp's ridley turtles, speculates that the collapse was driven by an exceptionally cold year in the northern Gulf. In this area, the turtles forage and gain strength to prepare for their long migration in spring to the breeding beaches in Mexico.
Another possibility is that the turtle population has outgrown the capacity of the gulf to support it.
But Heppell says that such a sudden collapse in 2010 is not consistent with this explanation. "Nest counts alone are not enough to point the finger at BP, as there are a number of things that could affect nest numbers," she says. However, we've never seen such a dramatic drop in one year as in 2010, she adds. Also, the recovery came to an abrupt halt, and didn't slow gradually as we might expect to happen if it was coming to some sort of environmental carrying capacity.
Status reviewed
Some answers may be forthcoming with the publication later this year of an updated five-year status review for Kemp's ridleys by the National Oceanic and Atmospheric Administration's National Marine Fisheries Service, and a Red List Assessment report by the marine-turtle specialist group of the International Union for Conservation of Nature.
BP issued a pre-emptive five-years-on assessment last month. This claimed that the clean-up operation has been a success and that the impacts on wildlife have not been as damaging as some may have anticipated, with the Gulf of Mexico "rebounding".
The report glossed over the effect on the turtles, claiming that changing trends in nesting "could be due to many factors including natural variability and cold temperatures".
Conservation groups such as the US National Wildlife Federation have published reports that paint the opposite picture.
And the Natural Resource Damage Assessment Trustees, including those from NOAA say it is inappropriate and premature for BP to reach conclusions about impacts from the spill before the completion of the official evaluations by the trustees.
"There are a number of plausible explanations for the turtle decline, and long-term research is critical to finding out the real answer," says Gallaway. But with cuts in funding from US Fish and Wildlife Service's for turtle research and secrecy amid ongoing legal cases against BP, this may prove hard to do. "No one can be forthcoming [with regard to data] because they need permission from whichever side is funding them," says Gallaway. "A lot of information is therefore not available because of confidentiality agreements."
Dolphins and whales under scrutiny
Turtles aren't the only large animals that seem to have been affected by the 2010 Gulf of Mexico oil spill.
In February at the 2015 Gulf of Mexico Oil Spill & Ecosystem Science Conference in Houston, Texas, several teams presented data on the fate of large mammals, and although most were unwilling to talk to New Scientist before full publication of their results, abstracts made public at the meeting hint at their findings.
Lori Schwacke of the National Oceanic and Atmospheric Administration in Charleston, South Carolina, and her colleagues compared blood and other samples from bottlenose dolphins caught between 2011 and 2014 in Barataria Bay, Louisiana – close to the spill zone – with samples from dolphins caught in Sarasota Bay in Florida, which was not affected by the spill.
The dolphins caught a year after the spill in Louisiana were five times as likely as the Florida ones to have lung disease, and a quarter of them had poor body condition. They also had a higher prevalence of inflammation, liver disorders and iron levels, although follow-up studies in 2013 and 2014 revealed that the scale of abnormalities has gradually been decreasing.
Sylvain De Guise of the University of Connecticut in Mansfield and his team measured and compared white blood cells from dolphins in the same two populations between 2011 and 2014. Those from the spill zone had immune-system changes that left them more vulnerable to bacterial infections, especially Brucella, which is linked with die-offs of newborn dolphins in the same area.
And Bruce Mate of Oregon State University in Newport and his team fitted six whales with tags, tracking them between 2010 and 2013. They found a region of the seabed that covered 4000 square kilometres and included the spill site where the whales no longer foraged, when compared with an earlier survey that tracked whale locations between 2001 and 2005.
Mate's team proposes that sperm whales no longer forage there because contamination has reduced populations of bottom-dwelling fish and the squid that feed on them, which are in turn prey for whales. If this leads to a long-term loss of habitat, they say, there should be more concern about such effects from potential subsequent spills.
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It's a tough life deep in the ocean, so you can't really blame the vampire squid for taking a break. All other species of soft-bodied cephalopod so far studied produce their offspring in one glorious bout of reproduction, usually just before they die. But not the vampire squid. This sinister-looking creature feeds on zooplankton and decaying organic material in its struggle to survive up to 3000 metres deep.
Henk-Jan Hoving at the Helmholtz Centre for Ocean Research in Kiel, Germany, and his team dissected 43 female vampire squid captured in tow nets off the coast of southern California. They found 20 adults that had released some eggs, but still had immature egg cells available for future spawning. One squid had released at least 3800 eggs, judging by her empty follicles, but still had around 6500 left.
Based on the number of eggs the team observed ripening together in batches, they estimated that the squid release about 100 eggs at a time – suggesting this female had already undergone at least 38 bouts of spawning, and could have gone on for another 65.
This could be an adaptation to their life in the deep ocean. "By reproducing in multiple cycles, it may allow vampire squid to make use of its low-calorie food source," says Hoving.
"This reproductive strategy gives advantages to the vampire squid to save energy in the very poor feeding conditions of the deep sea environment," says Bahadir Önsoy of Mugla Sitki Kocman University in Turkey. "In deep sea habitats, the temperature is low, so the metabolism of an animal that lives there is expected to be slow."
Daniel Stephen of Utah Valley University in Orem agrees the strategy is probably an adaptation to the squid's environment, but he isn't surprised. Repeated bouts of spawning are known in their shelled relatives, the nautiluses.
Journal reference: Current Biology, DOI: 10.1016/j.cub.2015.02.018
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Lucy, arguably the world's most famous early human fossil, is not quite all she seems. A careful look at the ancient hominin's skeleton suggests one bone may actually belong to a baboon.
In November 1974, palaeoanthropologists Donald Johanson and Tom Gray made the discovery of a lifetime near the village of Hadar in Ethiopia: dozens of fossil fragments belonging to a single hominin skeleton dating back 3.2 million years.
Once the fragments had been pieced together, the skeleton was declared to be of the species Australopithecus afarensis. But the skeleton became known as Lucy, inspired by a Beatles song that blasted out of a cassette player as the researchers celebrated their discovery that evening.
Forty years later, thanks to its age and completeness, Lucy remains an important specimen. It shows, for instance, that our distant ancestors began to walk upright on two legs long before they developed big brains.
It's no surprise, then, that replicas of the skeleton are on display at museums across the world. But when Gary Sawyer and Mike Smith at the American Museum of Natural History in New York recently began work on a new reconstruction of Lucy's skeleton, with help from Scott Williams at New York University, they noticed something odd.
"Mike pointed out that one of the [vertebra] fragments, which no one, including me, had really paid close attention to, looked fairly small to fit with the rest of Lucy's vertebral column," says Williams.
Williams had been working with Marc Meyer at Chaffey College in Rancho Cucamonga, California, on the spinal column of another early hominin, Australopithecus sediba, and so the two researchers decided to study the fragment.
They soon concluded that it didn't belong to Lucy. "It was just too small," says Williams.
One possible explanation was that the vertebra fragment came from a second, juvenile member of Lucy's species. So Williams and Meyer did a comparative study that included vertebrae from other Australopithecus fossils. To satisfy a personal hunch, Williams also added vertebrae from other animals known to have lived in the Hadar region 3.2 million years ago, such as porcupines and pigs. The results showed, surprisingly, that the fragment may not have belonged to Australopithecus at all.
"Baboons were a close match, both in shape and size," says Williams. "So we think we've solved this mystery. It seems that a fossil gelada baboon thoracic vertebra washed or was otherwise transported in the mix of Lucy's remains."
He stresses, though, that the analysis, which he will present at a meeting of the Paleoanthropology Society in San Francisco next week, also confirms that the other 88 fossil fragments belonging to Lucy's skeleton are correctly identified. And the mislabelled baboon bone fragment doesn't undermine Lucy's important position in the evolution of our lineage.
There may be a simple reason why no one noticed that Lucy's remains included a baboon bone fragment.
Although many scientists have examined Lucy's skeleton, most experts have not worked as extensively on bones of the back relative to the limbs, says Dan Gebo at the Northern Illinois University in DeKalb. "Given that broken bones are always a problem and most of us are not vertebral specialists, it would not be unusual to make a small mistake."
Also, there was no sign of a baboon skeleton at the site where Lucy was discovered in 1974, says William Sanders at the University of Michigan in Ann Arbor. "So there was no reason to assume intermingling of elements between two different animals," he says.
Even so, Sanders wants to see the analysis in detail before he accepts that the vertebra fragment really does belong to a baboon. "Offhand, I don't see any morphological features in this element that cry out for recognition as a baboon," he says.
If the fragment really does prove to belong to a baboon, he says, "we can cut Don Johanson and his colleagues some slack".
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Liquid water collects in the Martian soil each night, before evaporating during the day, according to NASA's Curiosity rover. If future missions can confirm this water cycle, it means astronauts could one day farm moisture to provide drinking water on Mars.
Planetary scientists have seen a lot of evidence for frozen water at the Martian poles, and water vapour in the planet's atmosphere. Liquid water, on the other hand, has been harder to come by, as the temperature and atmospheric pressure at the surface is too low.
But the soil on Mars is known to host perchlorate salts, which lower the freezing point of water, meaning the chilly surface conditions are not an absolute barrier to liquid water.
Images from NASA's Phoenix lander in 2009 suggested it had liquid water running down one leg, but this sighting may also have been ice, leaving the case for liquid water inconclusive.
Martian nights
So Javier Martin-Torres of the Luleå University of Technology in Kiruna, Sweden, and colleagues have tracked the weather conditions on Mars throughout Curiosity's first Martian year, recording humidity, air and ground temperatures with its Rover Environmental Monitoring Station (REMS).
The team found that during Martian winter, conditions throughout the cold but humid nights would allow liquid water to be stable in the first 5 centimetres of the surface. Shorter periods of stability would also be possible in other seasons.
They suggest that calcium perchlorate in the ground absorbs water from the atmosphere until it dissolves into a salty solution, or brine. This process is called deliquescence. When the sun comes up and the temperature rises, the water evaporates and returns to the atmosphere, starting the cycle anew.
Curiosity can't measure this water directly, says Martin-Torres, but everything is in place for it to be there. "We find the conditions for brines to be produced, but if you want to measure them directly you need some other kind of measurement," he says, such as an instrument that can look for changes in electrical conductivity.
A briney solution
Alfonso Davila of the SETI Institute in Mountain View, California, says there is not enough evidence to be certain that there is liquid water on the current surface of Mars, but the result does indicate that the planet was previously wetter. "To me, the work is significant because it suggests that deliquescence processes could have been important in the past, when there was more water in the atmosphere and the temperatures were higher," he says.
If the water is there, it's unlikely to harbour life, as the temperature is below -30 °C on average – too cold for even extreme Earth microbes to replicate and metabolise. "The fact that no microorganisms on Earth can grow at temperatures lower than -20 °C or so suggests that this could be a hard limit for water-based life," says Davila.
This water might one day help life flourish on Mars in other ways, however. Martin-Torres is currently working on a proposed device for the European Space Agency's ExoMars rover, due to launch in 2018, that would exploit Curiosity's findings. "It's a proof of concept of an instrument that will take water out of the atmosphere to produce liquid water for astronauts," he says. Small containers holding salts and mounted on the rover would mimic the natural deliquescence process. If it works, future astronauts could do the same on a larger scale to support Mars exploration.
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Did ancient ammonites sink or swim? This X-ray image of a fossil is bringing their shells back to life to help tell us if they could move freely through water.
We think that ammonites, which lived up to 65 million years ago, used their shells as a flotation device, pumping out water through gaps in the structure and filling them up with buoyant gas. The photo below shows what the actual holes look like.
(Image: Damian Gorczany)
To work out whether the structure would have allowed for swimming, René Hoffmann of Ruhr University in Bochum, Germany, used X-rays to produce a 3D model of an ammonite. Using the reconstructions, he was able to calculate the ammonite's weight and volume, and thus determine whether the chambers really could help it float. To check his results, he also created models of the nautilus, a present-day relative of ammonites that are able to float. Since he could access living specimens, he was able to compare their body weight with calculations based on the volume and density of the simulated shell.
His results suggest that young ammonite shells had 11 chambers, enough to keep hatchlings afloat. Although he has yet to confirm the buoyancy of adults, ammonites developed more shell chambers as they aged and became heavier, which would have helped support them in the water.
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(Image: Flávio H. G. Rodrigues)
(Image: Flávio H. G. Rodrigues)
(Image: Stuart Franklin / Magnum Photos) 
Not so tough: A leatherback turtle munches on a pyrosome in the Azores (Image: Brian Skerry/National Geographic Magazine)
The number of nests of Kemp's ridley turtles dropped massively in 2010, when the Deepwater Horizon oil spill happened (Image: Erich Schlegel/Corbis)
(Image: René Hoffmann)
(Image: Damian Gorczany)