1-31-19 Giant pandas may have only recently switched to eating mostly bamboo
The switch to a bamboo diet occurred some 5,000 years ago, not 2 million years ago as thought. When it comes to deciding what’s for breakfast, lunch or dinner, pandas have it easy: Bamboo, bamboo and more bamboo. But that wasn’t always the case. Although modern giant pandas (Ailuropoda melanoleuca) chow almost exclusively on bamboo in the mountain forests of central China, these bears’ diet was much broader not so long ago, researchers report online January 31 in Current Biology. Analyses using chemical signatures from bones and teeth of both ancient and modern pandas indicate the bears’ hyperdependence on bamboo could have developed as recently as about 5,000 years ago. That’s roughly 2 million years later than previously assumed from molecular and paleontological data. “It has been widely accepted that giant pandas have exclusively fed on bamboo for a long time, but our results show the opposite,” says Fuwen Wei, a wildlife ecologist at the Chinese Academy of Sciences’ Institute of Zoology in Beijing. “That made us excited.” Wei and his colleagues compared the relative abundance of isotopes — atoms of the same element but with a different number of neutrons in the nucleus — in modern and fossil animals, including pandas. Animal diets contain different amounts of naturally occurring “heavy” and “light” isotopes of carbon, oxygen and nitrogen that are then incorporated into bones, hair, nails and teeth. The ratio in which the isotopes occur in the body depends on the animal’s position in the food chain and the climate in which the animal lives. Carnivores, for example, have a higher abundance of the heavy nitrogen-15 isotope because they almost exclusively consume meat, which is made of nitrogen-rich amino acids. And animals living in cold, dry places tend to consume a higher abundance of the heavy oxygen-18 isotope in what they eat and drink because the heavy isotope doesn’t evaporate from that environment as easily as it does in warm, wet conditions.
1-30-19 Scientists name 66 species as potential biodiversity threats to EU
Threats include a North American squirrel, a venomous catfish and crayfish from the Ohio River. North America’s fox squirrel, the venomous striped eel catfish (SN: 4/29/17, p. 28) and 64 other species are now considered invasive threats to existing species in the European Union, scientists report online on December 12 in Global Change Biology. Emphasis on the word ‘threat.’ None of these organisms have been found yet in the EU, except for in captivity. The goal in listing and evaluating invasive threats is to prevent these species from ever crossing EU borders and establishing themselves, says coauthor Helen Roy, an ecologist at the Centre for Ecology and Hydrology in Wallingford, England. Roy and colleagues whittled a European watch list of 329 invasive species down to 66 using a technique called “horizon scanning.” Experts scored the likelihood of each creature arriving in the EU within the next decade, establishing itself, spreading and changing local ecosystems. This effort is the first time horizon scanning has been used on a continental scale to account for so many taxonomic groups. The eight most worrying species include East Asia’s voracious northern snakehead, a fish that has wreaked havoc in U.S. waters since the early 2000s (SN Online: 7/8/14). Also on the “very high risk” list to biodiversity are the aggressive rusty crayfish, a species native to the Ohio River that can spread fungus or diseases harmful to local species, and Asia’s golden mussels, prone to accumulating on native plants and clogging pipes. Many of the most worrying species are expected to invade EU territory within 10 years and out-compete native species. If the invasions occur, it will likely be due to human activities. Species could stowaway aboard an airplane or ship or could escape from confinement from a zoo or research lab.
1-29-19 Using CRISPR to stop male calves being born may lower animal suffering
For many livestock animals, being born male means an instant death sentence. Male dairy calves are unwanted because they do not produce milk, while male chickens are routinely killed as soon as they hatch because they do not lay eggs. Now researchers are proposing a radical solution to this slaughter: genetically engineering the animals we eat so that they mostly produce female offspring. The idea could reduce animal suffering and improve farms’ profitability, but is likely to collide with public opposition to genetically-modified organisms. Researchers led by Motti Gerlic and Udi Qimron of Tel Aviv University in Israel have devised a system to ensure that male animals are rarely born. They worked with mice, which are not livestock animals, so their study is a proof of principle rather than something that could immediately be used on farms. Like humans, female mice have two X chromosomes while males have one X and one Y. The researchers used CRISPR gene editing to automatically destroy Y-chromosomes in unborn embryos, causing them to abort at an early stage. The team modified the genome of one group of mice to include a key CRISPR enzyme called Cas9, which cuts DNA in specified places. In a second group of mice, they added markers to three genes on the Y chromosome, making them a target for Cas9. Each gene is essential for embryos to develop, so damaging even one of them would cause the embryo to abort. They targeted three to be extra sure. In theory, when these two lines of modified mice mated with each other, only female offspring should have been born. The team found that such crosses produced just three males for every 20 females, so the method shows promise, but may need to target more genes to be fully effective.
1-25-19 Male birds’ sexy songs may not advertise their brains after all
A biologist rejects an idea he studied for years that quality birdsong is a sign of bird smarts. After some 20 years of theorizing, a scientist is publicly renouncing the “beautiful hypothesis” that male birds’ sexy songs could indicate the quality of their brains. Behavioral ecologist Steve Nowicki of Duke University called birdsong “unreliable” as a clue for choosy females seeking a smart mate, in a paper published in the March 2018 Animal Behaviour. He will also soon publish another critique based on male songbirds that failed to score consistently on learning tests. And in what he calls a “public service announcement,” Nowicki summarized the negative results of those tests on January 4 at the annual meeting of the Society for Integrative and Comparative Biology in Tampa, Fla. “This was a beautiful hypothesis that got beaten up by data,” he says. Knowing that something about male singing matters to a female songbird, Nowicki and other researchers once proposed that the quality of singing might indicate a bird’s brainpower. The idea was that, because songbirds need to learn their songs, females could select males with the best brain development by selecting those singing the most precisely copied songs. A brainier male might be better at hunting baby food or spotting predators, thus helping more chicks to survive. Or braininess might signal an indirect benefit, such as contributing good genes to chicks.
1-24-19 Some snails wear jackets made of algae to protect them from the sun
Beach life can be tough for creatures that endure ocean tides every day. One species of marine snail, however, appears to have found a clever way of coping with the dramatic changes in conditions – they wear heatproof coats. A type of turban snail, so-called because of the shape of their shells, is often found on rocky shorelines around Japan covered in a mat of green algae. While most turban snails will eagerly feast upon algae, Lunella coreensis accumulates it as a vegetative jacket as they grow, until they are entirely covered in it at maturity. The algae itself also appears to only grow on the shells of this snail, although the reason why was a mystery. Now a study suggests the algae insulates the snails from sudden shifts in temperature as the tide recedes. “The snails are regularly out of water and are exposed to sun at low tide,” says Osamu Kagawa, a marine biology student at Tohoku University and lead author of the study. “The difference in temperature between low tide and high tide is sometimes more than 20°C.” Kagawa and his colleague Satoshi Chiba noticed snails on boulders close to sandy areas of beach often lacked algal coats while those inhabiting rockier areas almost entirely did. When the pair collected the coatless snails, they were far less hardy than those blessed with a covering of algae. Snails left under heat lamps in the laboratory for 30 minutes – an attempt to mimic the heat of the sun on the beach after the tide has gone out – suffered nearly double the mortality rate if they lacked algae compared to those with it.
1-23-19 Young emperor penguins brave icy, winter waters in their first year
The young birds head north to warmer waters before returning to winter in Antarctica. Only months after their first ocean swim, young emperor penguins are braving Antarctica’s treacherous winter seas. GPS trackers strapped to 15 young penguins showed the birds venturing north to warmer waters beyond Antarctica’s pack ice in December 2013, and returning a few months later as the waters chill. That finding surprised some scientists, who thought the inexperienced juveniles might play it safe closer to the Antarctic sea ice’s edge rather than risk freezing or drowning in the choppy open sea. After all, “they just learned how to dive a few months beforehand,” says marine ecologist Sara Labrousse at the Woods Hole Oceanographic Institute in Massachusetts. But within a few weeks of being on their own, at around 5 months old, these plucky penguins were already diving to depths of around 100 meters, like adults do, the researchers report January 17 in Marine Ecology Progress Series. That’s just after they had shed their fluffy down, and before they had built up an insulating fat layer. The tracked birds then headed more than 1,000 kilometers north to open, ice-free waters, in some cases reaching points roughly halfway between Antarctica and Australia. Data from more than 62,000 dives indicate the emperor penguins (Aptenodytes forsteri) made mostly shallow dives there, likely hunting fish and krill that feast on floating algae, the authors say. In March or April, when the birds were about 8–9 months old, the fattened youngsters returned south and ventured back to Antarctica’s sea ice for winter.
1-23-19 A CRISPR gene drive for mice is one step closer to reality
The genetic tool might one day help control invasive wild rodents. Scientists are getting closer to creating a genetic pest-control measure against rodents. Female mice engineered to carry a genetic cut-and-paste machine called a gene drive may be able to pass a particular version of one gene on to more than 80 percent of their offspring, researchers report January 23 in Nature. That rate would beat the usual 50 percent chance of handing down a gene variant, first reported in 1865 by Gregor Mendel from his studies of peas. “What we’ve done is engineered a gene that can be inherited more frequently than it would be by normal Mendelian inheritance,” says Kimberly Cooper, a developmental geneticist at the University of California, San Diego. “My graduate student likes to call it ‘cheating Mendel.’” Such engineered genetic cheats have been proposed to wipe out disease-carrying mosquitoes and invasive species by targeting genes involved in reproduction (SN: 12/12/15, p. 16). Gene drives might also be used to prevent pests from carrying diseases, such as malaria (SN: 12/26/15, p. 6). Researchers have made successful gene drives in laboratory experiments in mosquitoes, fruit flies and yeast. But no one has yet built one that works in a mammal. And Cooper isn’t claiming to have done so either. By definition, a gene drive must cheat Mendelian inheritance rules over multiple generations, spreading itself to an entire population. Cooper’s group has produced one generation of genetic cheater mice, but hasn’t yet tracked the gene drive’s spread through multiple generations.
1-21-19 Probability helps zebrafish stay in schools when faced with predators
Zebrafish are exceptionally good synchronised swimmers, forming tight schools that contain hundreds of individuals. Physicists have shown how the fish stay together even as they swim faster to avoid a predator – and they do so by subconsciously performing the kind of weighted averages calculation familiar to high-school mathematics students. Small fishes tend to swim in schools. Sticking together decreases the risk of any individual fish being killed by predators, and biologists say a school of fish can have more foraging success because many eyes are better than two when it comes to searching for food. Scientists have built mathematical models to understand how fish manage to swim so closely to dozens of others without colliding. They found that in order to maintain the schools’ structure, every fish keeps tabs on what many of its peers are doing – their speed, orientation, and any changes in either of these. Gonzalo de Polavieja at the Champalimaud Centre for the Unknown in Portugal wanted to know if these rules still applied when the school comes under attack from a predator and the fish must swim faster. With his colleagues, de Polavieja tracked the movement and speed of over 200 zebrafish swimming in groups in fishtanks in their lab. Through modelling, they found the earlier mathematical models no longer apply when the fish move quickly – at more than three body lengths per second. At these higher speeds, the fish collect the bare minimum information they need to avoid collisions and synchronise their swimming with others. The model shows each fish considers the position, speed and direction of just five neighbours on average. Even then, not all of them matter equally. The movement and speed of neighbours that swim faster or are closer have the biggest impact on the direction and speed of any individual fish.
1-21-19 Astronauts could use fish and human waste to grow food on long trips
Fish may be key to sustaining people on a long space mission. A well-stocked aquarium could provide enough extra nutrients to feed the astronauts’ crops, while also offering a source of protein. The ideal spaceship is a closed system, where those on board can grow everything they need to survive and all waste is processed for reuse. On the International Space Station, for example, urine is collected and processed so that it is safe to drink. For growing crops, one approach would be to use human waste as a plant feed. However, it turns out this alone is not enough, as plants need more calcium, magnesium, phosphorus and sulphur than it contains. Carrying extra nutrients on board would take up space and they could run out if the journey took longer than expected. A team from the Krasnoyarsk Scientific Centre in Russia discovered that travelling with crucian carp could complete the loop. They found that the left-over parts of a carp dinner, such as the bones, scales and internal organs, would be enough to make a nutritionally complete plant feed. To make the mix, space travellers would first have to create hydrogen peroxide from water and oxygen. This would be placed in an alternating current alongside human waste and the leftover fish parts. Around three hours later, the hydrogen peroxide would decompose into water and oxygen. The results would then be mixed with nitric acid, which could also be synthesised from urine, to create the plant food. To test the recipe, the team fed this mix to wheat plants on Earth. They found that after 180 days, the crop had grown to a similar size as would be expected with regular plant feed.
1-19-19 Cryptic remains of tiny animals have turned up in an Antarctic lake
Mud from Lake Mercer revealed crushed critters that resembled spiders and worms. Much to their surprise, scientists in Antarctica have uncovered what appear to be remnants of tiny animals in mud dredged from a lake that has been covered by a thick mantle of ice for thousands of years. The researchers on this expedition — known as the Subglacial Antarctic Lakes Scientific Access, or SALSA — are the first to sample Lake Mercer, a body of water about 600 kilometers from the South Pole. After drilling about a kilometer through the ice in late December, researchers lowered instruments that brought water and sediment up to the surface. Looking at these samples under a microscope, the team found “some things that looked like squished spiders and crustacean-type things with legs … some other things that looked like they could be worms,” says expedition member David Harwood, a micropaleontologist at the University of Nebraska–Lincoln. The researchers also spotted what appeared to be the vestige of a famously durable microscopic critter called a water bear (SN Online: 7/14/17). Examining the DNA of these remnants will help researchers ID them more precisely. This find, first reported online by Nature on January 18, “is really intriguing,” says Slawek Tulaczyk, a glaciologist at the University of California, Santa Cruz who is not part of the SALSA team. Until now, scientists hadn’t considered such Antarctic lakes like Mercer to be suitable environments for organisms larger than microbes.
1-18-19 We’ve dug up tiny animals from beneath a frozen Antarctic lake
During the last decade, researchers began drilling into Antarctica’s ice-covered lakes in search of life. Now we have what may be the clearest evidence yet of biologically complex life in one of these lakes – although it’s not yet clear whether any of the animals are currently alive. According to a report in Nature, a few weeks ago a team of US biologists discovered the preserved carcasses of tiny crustaceans and tardigrades in the mud at the bottom of Lake Mercer, which lies beneath a kilometre of ice. The discovery raises two questions: how did the animals get there, and are there any still living in the lake today? According to the report, animal ecologist Byron Adams at Brigham Young University in Utah has had a chance to examine the dead animals and other organic remains in the mud. He has noticed similarities to communities that once lived in the Dry Valleys, a few hundreds of kilometres from Lake Mercer, and also in the Transantarctic Mountains a few tens of kilometres from the lake. He suspects the animals lived in rivers or lakes in the mountains when the climate was briefly warmer, perhaps just a few thousand years ago. From there, the animal carcasses were somehow washed into Lake Mercer – perhaps, according to other researchers, in rivers that run beneath the ice. This would suggest that Lake Mercer is simply an animal graveyard rather than a body of water with living animal communities. That might make sense. Lake Mercer is buried beneath a layer of ice so thick that no light can reach the water. The microbes living there may grow too slowly to support communities of animals, Nature reports.
1-18-19 This honeybee parasite may be more of a fat stealer than a bloodsucker
New looks at a hive’s nightmare challenge a decades-long assumption about Varroa destructor. Tests with fake bee larvae reveal that a “vampire” mite attacking honeybees may not be so much a bloodsucker as a fat slurper. The ominously named Varroa destructor mite invaded North America in the 1980s, and has become one of the biggest threats to honeybees. Based on research from the 1970s, scientists thought that the parasitic mites feed on the bee version of blood, called hemolymph. But the mites are actually after the fat of young and adult honeybees, says entomologist Samuel Ramsey, who is joining the U.S. Department of Agriculture’s Bee Research Laboratory in Beltsville, Md. That insight might aid the largely failed efforts to develop antimite compounds for feeding to bees, says toxicologist Aaron Gross of Virginia Tech in Blacksburg. He has documented mites resisting some of the current controls and hopes for new options. Ramsey’s rethink started with Varroa biology. For instance, the mites don’t have the more flexible body that can swell with a lot of incoming fluid or a gut specialized for elaborate liquid filtering that many other bloodsuckers do. And insect hemolymph looked to Ramsey like a weak, watery choice for exclusive nutrition. So Ramsey spent about a year while at the University of Maryland in College Park developing artificial bee larvae from gelatin capsules that let him test how well mites survived when fed different proportions of fat from an organ called the bee fat body versus hemolymph. Mites lived for just 1.8 days on average on pure hemolymph. The only ones to survive the entire seven-day tests — though few in number — ate 50 percent or 100 percent fat.
1-18-19 Fat dogs die early
If you can’t persuade your family to stop feeding your dog scraps from the dinner table, try this line of argument: They could be cutting short poor Fido’s life. Researchers looked at the life spans of 50,000 dogs taken to veterinarians in the U.S. between 1994 and 2015. The hounds were from 12 of the most popular family breeds, and included dachshunds, golden retrievers, and Labrador retrievers. Researchers found that being overweight was linked to a reduced life span in every one of the breeds: from five months shorter in German shepherds to two and a half years in Yorkshire terriers. The study didn’t explore why chubby dogs died earlier than svelte ones, but previous research has shown that overweight pooches are more likely to suffer from joint disease, breathing issues, and cancer, all of which can reduce longevity. Co-author Alex German, from the University of Liverpool, tells ScienceDaily.com: “Being careful about what you feed your dog could go a long way toward keeping them in good shape and enabling them to be around for many years to come.”
1-18-19 Peacocks might use their showy tails for covert communication
Peacock tails are brightly coloured and highly conspicuous – but maybe not to their predators. The animals that hunt peacocks have poor colour vision and, to their eyes, the birds’ tails may actually help them blend into the background. However, it is not clear whether this colour-based camouflage helps the peacocks much, because they make themselves noticeable in so many other ways. Peacocks are male Indian peafowl (Pavo cristatus). When they court the female peahens, they display an enormous tail decorated with iridescent eyespots. All else being equal, peahens prefer males with more elaborate and beautiful tails. We had thought that the tail’s bright colours also attract the attention of predators. In the birds’ native south Asia, the threats include tigers, leopards and stray dogs. But it is not obvious that these animals would take notice of peacock tails, because their colour vision is not as good as ours, argue Suzanne Amador Kane of Haverford College in Pennsylvania and her colleagues. Human eyes have three kinds of colour-sensitive receptors, which mean most of us can tell the difference between colours like red and green. But cats and dogs only have two colour-sensitive receptors, so some hues look the same to them. Kane’s team used spectroscopes to measure the light reflected be peacock tails, to determine their exact colours. Then they calculated how the tails would appear to other peafowl, and to their predators. They found that the famous eyespots are conspicuous to peafowl but blend in for the predators. What’s more, when shown against a background of foliage the peacock tails further blended in. The team argues that peacock tails have evolved to form a kind of secret communication channel that other peafowl can see, but which their predators are not aware of.
1-17-19 BBC America's new animal documentary Dynasties is more gripping than Game of Thrones
A queen locked in a bloody war against her power-hungry daughter. A grande dame struggling to keep her subjects alive. A princeling abducted from his parents by a jealous emperor. Each could easily be subplots in Game of Thrones, but these stories instead make up three of the five episodes in BBC America's new nature documentary series, Dynasties. Cleverly focusing on the ruling family unit as it exists in nature, the show's twist on the natural history genre makes Dynasties as gripping as any human royal drama, fictional or otherwise. Four years in the making, Dynasties comes from the same group behind the beloved productions Planet Earth II and Blue Planet II. Each of the five hour-long episodes are presented by the inimitable 92-year-old David Attenborough, and will be simulcast beginning Saturday across the BBC America, AMC, IFC, and SundanceTV channels. Specifically, Dynasties zeroes in on five different animal "characters": Charm the lioness; David the chimpanzee; Raj Bhera the tigeress; and Tait and Blacktip the painted wolves. There's also a colony of emperor penguins. But unlike other nature documentaries that dutifully narrate the onscreen action, Dynasties, as the name suggests, applies a monarchical frame to its animal matriarchs and patriarchs. "We join each family at a crucial moment in their lives, when they're battling against the odds, fighting for survival against the elements and against rivals," Attenborough explains in the show's intro. And because of the incredible access the videographer teams had with their subjects — several of the episodes took two years to complete — Dynasties makes you feel as if you know David and Blacktip the way you know Catelyn Stark and Daenerys Targaryen. (Hyenas, which appear as the villains in two of the episodes, are undoubtedly the White Walkers in this analogy).
1-17-19 This rediscovered Bolivian frog species survived deadly chytrid fungus
The species was feared to be extinct, except for one lonely male. Save for one “lonely” survivor in captivity, the Sehuencas water frog hadn’t been seen in the wild since 2008. That’s when its numbers collapsed, primarily due to chytridiomycosis, a fungal disease that has devastated frog populations worldwide. Fearing the species might be extinct, some scientists spent 10 years searching the Bolivian mountain forests for the amphibians. Now, they’ve found a tiny population of five. “It’s just incredible,” says herpetologist Robin Moore, communications director at Global Wildlife Conservation in Austin, Texas. He was among the scientists who announced the discovery on January 15. With no current way to get rid of the lethal chytrid fungus in the wild, scientists are keen to study the survivors, Moore says. The five Sehuencas water frogs (Telmatobius yuracare) were found in their native habitat: the Bolivian mountain cloud forests, where the climate is moist and cool — and ideal for chytrid to grow. “It could be that this small population has immunity” or genetic resistance, Moore says. “It could be an environmental factor,” such as an unusually warm microclimate. It could also just be nature’s luck. “Many species of frogs that disappeared for years — decades in some cases — have been seen again later,” says ecologist Karen Lips of the University of Maryland in College Park. In December 2018, for example, researchers announced they had rediscovered Ecuador’s marsupial horned frog, more than 10 years after the species disappeared.
1-16-19 Manatees, whales and turtles are coming back from the brink in the US
The US’s Endangered Species Act is even more effective than we thought. We already knew it has helped save many terrestrial plants and animals. Now it’s also been shown to have helped many marine mammals and turtles. The act provides considerable protection for the 2000 species assessed to be endangered or likely to become endangered, such as the iconic bald eagle. It has been estimated that 227 species would have gone extinct by 2006 were it not for the 1973 act. But no one had done an overall assessment of how well it has worked for the 60-odd marine mammals and turtles listed, including the Antillean manatee, the sei whale and Kemp’s ridley turtle. Now Abel Valdivia of the Center for Biological Diversity in California and colleagues have crunched the numbers for 31 populations of 19 different species. The team concludes that 24 of these populations are recovering, five are stable and just two continue to decline. The recovering ones include the Guadalupe fur seal, the green sea turtle and the Pacific population of fin whales, which has increased from under 2000 to nearly 10,000. The recovering populations have all been listed as under threat for 20 years or more. However, the act – long attacked by critics who say it holds back development – is itself endangered. Last July, the Trump administration made proposals that would greatly weaken it. If the proposed changes were in place in the 1970s, the bald eagle would be extinct today, Brett Hartl at the Center for Biological Diversity said at the time the proposals were made. “These proposals would slam a wrecking ball into the most crucial protections for our most endangered wildlife.”
1-16-19 Long penises help hermit crabs avoid being robbed during sex
Some hermit crabs have unusually large penises, and now we might know why. A long penis allows a male crab to have sex without leaving the shell he calls home, reducing the risk it will be stolen while he is busy. Many species of hermit crabs protect themselves from predators by moving into empty mollusc shells, which they then carry around with them. Mark Laidre at Dartmouth College, New Hampshire, calls the mollusc shells a form of hermit crab private property. A few hermit crab species – especially those in a group called the Coenobita – modify their private property: spending months or even years tearing away some of hard material inside the shell to make it a roomier and more comfortable dwelling. But remodelled shells are potentially seen as more desirable, which can make them a tempting target for theft by another hermit crab especially when the homeowner is preoccupied. Laidre wondered whether this risk of theft might explain a curious feature of Coenobita hermit crab anatomy – namely, that some males have penises that can be 60 per cent as long as the rest of their bodies. Laidre’s idea was that a male with a larger penis can remain inside his valuable home during sex and simply extend his penis out of the shell towards the female. A male with a shorter penis would have to creep out of his shell for sex, which would mean leaving his private property unoccupied and at risk of being stolen. Laidre dubs this the ‘private parts for private property’ hypothesis.
1-16-19 How hagfish can make enough slime to clog a shark’s jaws in seconds
When a hagfish is attacked by a shark, it spews out a defensive slime that clogs up the predator’s jaws, allowing the hagfish to escape. The slime rapidly expands in milliseconds, and now we know how. Gaurav Chaudhary at the University of Illinois at Urbana-Champaign and his colleagues modelled the hydrodynamics of hagfish slime, determining the mathematics that govern the goo. Hagfish slime is made up of mucus cells and 1-micrometre-thick thread-like fibres. Each of these fibres is about 10 to 16 centimetres long, and is twisted into a ball that is a fraction of a millimetre in diameter. It looks a little like a skein of yarn with a single loose thread sticking out of one side. When deployed, such threads fully unravel in under 0.4 seconds to help form a fibrous network for the mucus to stick to. “Some experiments have suggested that the threads unravel because seawater dissolves a protective membrane around them, but the timescale doesn’t work,” Chaudhary says. “It happens much faster than that in nature.” To figure out how the threads unravel so quickly, Chaudhary first tested whether a skein would fully unravel on its own in salt water, or whether it required force pulling on the loose end of the thread. “Only when I applied force did it unravel,” he says. Then he and his team explored the various forces that would pull the loose threads in a shark-eat-hagfish situation. They modelled a number of scenarios, including one where the loose thread was stuck to a surface but the skein itself was floating free, one where the skein was stuck and the thread was floating free, and one where both were free.
1-16-19 Cuttlefish embryos can see and recognise predators before they hatch
CUTTLEFISH can see and respond to threats while still in the egg. Even more impressively, they can learn to recognise predators by sight days before they hatch. “They are pretty smart,” says Anne-Sophie Darmaillacq of the University of Caen Normandy in France. Many animals are forced to fend for themselves from the moment they hatch. Some fish and amphibians can sense the outside world while still in the egg and start preparing for the conditions they will face. For instance, salamanders exposed to the scent of predators while in the egg will spend more time sheltering after they hatch. Now Darmaillacq and her colleagues have shown that embryos of pharaoh cuttlefish (Sepia pharaonis), which grow in eggs that are nearly transparent, can respond to the sight of predators and to cuttlefish ink. Male pharaoh cuttlefish die soon after mating and the females die after laying eggs, usually placing them under rocks on the seabed. So for the 24 days or so it takes for the eggs to develop, the offspring are on their own. For the last few days they can see what is happening around them. The team put cuttlefish embryos in the final stages of development into small, sealed glass containers. These were then put inside a larger tank. When pufferfish, which eat cuttlefish eggs, were placed in the tank, the breathing rate of the embryos fell. This is thought to be part of a “freeze” response that makes the eggs harder to spot by reducing movement. It also reduces the strength of electric impulses from their nerves and muscles that can be sensed by sharks. The embryos responded in a similar way when exposed to clouds of black ink like those released by adult cuttlefish fleeing predators. But they didn’t react to clownfish, which don’t eat cuttlefish eggs.
1-15-19 How one heatwave killed 'a third' of a bat species in Australia
Over two days in November, record-breaking heat in Australia's north wiped out almost one-third of the nation's spectacled flying foxes, according to researchers. The animals, also known as spectacled fruit bats, were unable to survive in temperatures which exceeded 42C. In the city of Cairns, locals saw bats toppling from trees into backyards, swimming pools and other locations. Wildlife rescuers found surviving animals clumped together, usually on branches closer to the ground. "It was totally depressing," one rescuer, David White, told the BBC. Lead researcher Dr Justin Welbergen, an ecologist, believes the "biblical scale" of deaths could be even higher - as many as 30,000 - because some settlements had not been counted. Australia had only an estimated 75,000 spectacled flying foxes before November, according to government-backed statistics. "This sort of event has not happened in Australia this far north since European settlement," says Dr Welbergen, who is also the president of the Australasian Bat Society, a not-for-profit conservation group. The spectacled flying fox - so named for light-coloured fur around its eyes - can also be found in Papua New Guinea, Indonesia and the Solomon Islands. In Australia, the species is only found in a small rainforest region of northern Queensland, where it helps to pollinate native trees. Dr Welbergen says about 10,000 bats of another species - black flying foxes - succumbed to the heat during the same two-day period. Flying foxes often experience fatal heat stress when temperatures eclipse 42C, scientists say. During November's heatwave, Cairns recorded its highest-ever temperature of 42.6C.
1-14-19 Dolphins unintentionally poisoning offspring with banned chemicals
Some industrial chemicals that were banned more than 30 years ago are still being passed on to dolphins born today. A new study has found that pollutants called polychlorinated biphenyls (PCBs), banned from use in Europe since the 1980s, persist in the Mediterranean Sea and show up in high quantities in bottlenose dolphins that swim those waters. Male dolphins were found to have significantly higher concentrations of PCBs in their blubber than females, which suggests that females offload these pollutants to their offspring. “Once a female has a calf, a lot of these fats will mobilise from their blubber into the milk, and consequently into the calf,” says Tilen Genov at the Slovenian Marine Mammal Society, who led the study. He says recent research also suggests that PCBs can be transferred through the placenta. Genov and his colleagues tracked 32 dolphins in the Gulf of Trieste from 2011 to 2017, taking samples of skin and blubber tissue. Overall 87.5 per cent of the dolphins had PCB concentrations above 9 milligrams per kilogram of lipid weight, the threshold at which physiological problems like hormonal disruptions begin, says Genov. Previous research has found that 41 milligrams per kilogram of lipid weight is the threshold of PCB contamination in ringed seals where reproduction begins to be impaired. In the current study, 65.6 per cent of the bottlenose dolphins had levels of PCBs in their blubber higher than this. Female dolphins that had not given birth also had significantly higher toxicity levels than females with calves. The pollutants affect firstborn dolphins more, because many of the toxins the female dolphin has accumulated throughout her life will find their way into her milk when she begins feeding her first infant. Provided she has calves at regular intervals, the level of contamination in her body tissue will stay relatively low.
1-14-19 Rich people’s gardens are better for bees and other pollinators
Pollinating insects, such as bees, seem to prefer richer areas. This may be because gardens in wealthier areas typically have a wider range of flowers. A team surveyed the distribution of plants and pollinating insects in four cities in the UK: Bristol, Edinburgh, Leeds and Reading. They found that residential, allotments and community gardens supported a greater abundance of pollinators than other types of urban land, such as parks and road verges. “This is consistent with the so-called ‘luxury effect’ whereby socioeconomic status is often positively correlated with urban biodiversity,” wrote the team in their paper. “In our case, the effect is driven by the greater quality of floral resources for pollinators in wealthier neighbourhoods.” Up to 50 times more bees were found in gardens than in areas with man-made surfaces including car parks and industrial estates. The authors recommend increasing the number of flowers in parks and other public green spaces and providing more allotments in towns and cities to increase the number of pollinating insects. “By understanding the impact of each urban land use on pollinators, whether it’s gardens, allotments, road verges or parks, we can make cities better places for pollinators,” says Jane Memmott at the University of Bristol, who runs the Urban Pollinators Project.
1-11-19 How worm blobs behave like a liquid and a solid
Scientists are studying how the animals move collectively when tangled together by the thousands. Blobs of worms flow like a fluid, plop like a solid and fascinate scientists. A worm by itself is as solid as any other living animal. But a mass of aquatic California blackworms tangled together flows through a tube like a liquid. Pouring, heating and otherwise playing with blobs of worms shows that a tangled mass of them has properties of both fluids and solids, Saad Bhamla reported January 5 at the annual meeting of the Society for Integrative and Comparative Biology. A blob can hold itself together like a solid: When released to fall a short distance on a hard surface, it plops instead of splashing, Bhamla, a biophysicist at Georgia Tech in Atlanta, said. And video from his lab also revealed a worm blob version of melting. In a container of water where a hot spot develops, the blob starts fraying and “melts” away as some blackworms (Lumbriculus variegatus) disentangle themselves and swim off, while others collectively move to a spot with a lower temperature. Adding chilly water, however, will cause the blob to solidify again as the animals rejoin the ball. Blobs of worms that ooze along as a mass might help advance the study of biological physics, Bhamla said. Unlike some more famous animal group behaviors, such as birds flocking or fish schooling, worms tangling in a blob nudge against each other and transfer forces directly. Such contact matters in some of biophysics’ profound questions about how little bits of soft matter come together as multicellular life.
1-10-19 Poison toilet paper reveals how termites help rainforests resist drought
Forests with more termites show better soil nutrient distribution and leaf litter removal. It took hundreds of teabags and thousands of rolls of toilet paper for tropical ecologist Kate Parr and her colleagues to demonstrate that termites help tropical rainforests resist drought. Forests with more termites show more soil moisture, leaf litter decomposition and seedling survival during a drought than forests with fewer termites, the scientists report January 10 in Science. The study was part of a project by the University of Liverpool and the Natural History Museum in London to examine how ants and termites affect decomposition and consumption of seeds, fruits and carcasses in rainforests of the Maliau Basin Conservation Area in northern Borneo. Termites play an important role in tropical ecosystems, but “nobody knows exactly how important they are,” says Parr from the University of Liverpool. To isolate the effect of termites from the other soil critters, Parr’s team exploited termites’ cellulose diet. In 2014, the researchers buried insecticide-soaked rolls of toilet paper as well as tainted teabags in four forest plots, each about the size of five Olympic swimming pools. Toilet rolls are like cotton candy for termites, Parr says, “this really amazing, easy-to-digest food for termites.” The team used poisoned teabags just in case some termites “were fussy and didn’t eat the toilet paper.” Termites died after eating the poisoned baits, while the 14 other most commonly found invertebrate groups, including ants and beetles, were unaffected. None of these other critters nosh on hard-to-digest cellulose.
1-10-19 Bumblebees lose sleep looking after the young by napping half as much
In some ways, bumblebees are just like us. When they’re tending to their queen’s offspring, they lose significantly more sleep than they do away from the presence of the brood. In bumblebee colonies, worker bees tend to the queen’s eggs as they move into the larva and then pupa stages before becoming adults. To see if this takes a toll on the amount of sleep the bees get, Guy Bloch at Hebrew University in Israel and his colleagues compared the sleep behaviour of bumblebees during periods of caring for the young and time away from the brood. Using high-speed video, they tracked bees as they moved around, considering a bee to be asleep if it was motionless for more than 5 minutes. Bees who were tending to larva, the worm-like state that worker bees feed with honey and pollen, got about twice as much daily sleep as those that were tending pupae, which the worker bees actively groom and incubate by wrapping their legs around it and vibrating their abdomens. For bees tending pupae, the number of naps they took decreased, but the duration of sleep each time did not. The presence of a pupa also increased the worker bee’s time spent building wax pots, which was correlated with reduced sleep. Pupae don’t need to be fed by the worker bees, so it’s not just the heightened activity of caring for their young that’s keeping bees up at night. Just the presence of empty cocoons was enough to impact the bees’ sleep.
1-10-19 Wasp eggs laid on paralysed insects emit gas that keeps victims fresh
A bee-killing wasp lays eggs that emit toxic gas – a food hygiene technique that keeps the larvae’s dinner fresh until they hatch. The European beewolf’s eggs spew out large amounts of nitric oxide (NO), which reacts with oxygen in the air to form nitrogen dioxide (NO2). The gases destroy microbes such as fungi that threaten food resources for the offspring. The beewolf paralyses its prey by stinging them with venon. It then lays eggs on the paralysed bodies of bees, which provides a handy meal for hatched larvae. But the dank soil where egg-laying occurs is microbe-rich, so the bees can get consumed by mould in the three days before larvae emerge. Fumigation prevents the hapless bee from spoiling. Erhard Strohm at the University of Regensburg got a whiff of the mechanism during experiments with beewolves that had laid eggs inside lab containers. A swimming pool aroma caused by NO2 was noticeable when the containers were opened. “The smell is really strong sometimes and it differs from brood cell to brood cell a bit,” he says. Strohm and his colleagues confirmed the presence of nitrogen oxides with a simple reactive dye test. “It’s kind of undeniably cool that the wasp has evolved mitigations for a pest control strategy,” says Tobin Hammer at the University of Texas at Austin. He says he can’t think of another example of naturally-occurring fumigation in the insect world. Nichole Broderick at the University of Connecticut says she is stumped too. Strohm and his team also identified a gene in the beewolf eggs that is missing a common instruction known to limit NO production. It is possible that this is why the eggs generate so much noxious gas.
1-10-19 Floating seabirds provide a novel way to trace ocean currents
Data from GPS trackers on shearwaters matched those collected by buoys and other tools. Seabirds are like feathered buoys. Gently rafting on the ocean’s surface, these birds go with the flow, making them excellent proxies for tracking changes in a current’s speed and direction. Oceanographers traditionally use radar, floating buoys or autonomous underwater vehicles to measure ocean current velocities, which can affect the climate, ecosystems and the movement of important seafood. But some ocean regions aren’t easily accessible. Seabirds lazily resting on the ocean surface could offer a novel alternative to collecting those data, researchers report online January 10 in Scientific Reports. “I don’t think it’s going to replace the various instruments we use,” says Evan Mason, a physical oceanographer at the University of Washington in Seattle. “It was just interesting to see what we might find.” Mason and his colleagues outfitted 75 Scopoli’s shearwaters (Calonectris diomedea), a seabird found in the Atlantic Ocean and Mediterranean Sea, with GPS tags and tracked their movements in the Balearic Sea off eastern Spain. On average, the birds spent only 10 percent of their time idly drifting on the water, but the team still collected 405 trajectories, the researchers say. Visually comparing wind and water velocity information with the way birds drifted, the researchers determined ocean currents, winds or both drove the animals’ direction, excluding some that preferred hitching a boat ride instead. The team then compared those tracks with satellite- and buoy-derived data of winds and surface currents and found they matched well.
1-9-19 Crows can guess the weight of an object by watching it sway in wind
It’s obvious to us that objects moved by a gentle breeze must be light, and those that don’t move are heavy, but can animals make this deduction? In the case of New Caledonian crows, the answer appears to be yes. “As humans, we have a very full understanding of what weight means across a variety of contexts,” says Sarah Jelbert, who led the study at the University of Cambridge, UK. “We don’t know if animals have these broad conceptions about the concept of weight in the same way that humans do.” Jelbert and her colleagues first trained 12 crows to discriminate between light and heavy objects. Six birds were rewarded when they dropped light objects into a food dispenser, and six were rewarded for choosing heavy objects. During this initial training, the birds were able to touch and pick up the objects. Then pairs of unfamiliar objects – one light and one heavy – were suspended from strings in front of an electric fan before the birds could interact with them. After seeing how they moved in front of the fan, the birds touched the correct object first, according to the rule they learned earlier, in 73 per cent of tests. If the test was done with the fan switched off, the birds did no better than chance. New Caledonian crows are famously fast learners with particularly impressive tool-making skills. In the wild, they often drop nuts on the ground to crack them open. The weight of a nut can indicate whether it’s good to eat, or rotten, so being able to infer weight by observation could be useful to them while foraging, says Jelbert.
1-8-19 Flowers hear bees and make sweeter nectar when they’re buzzing nearby
Evening primrose flowers can hear approaching bees and quickly make their nectar sweeter in response to the sound. Lilach Hadany and colleagues at Tel-Aviv University, Israel, collected nectar from flowers before and after exposing them to a range of sounds, including recordings of bees and synthetic noises. Within three minutes of exposure to bee sounds or artificial sounds of a similar frequency, the flowers increased the concentration of sugar in their nectar by 20 per cent on average. There was no change in sugar levels in flowers played no sound, or higher-frequency sounds. Bees are highly sensitive to differences in sugar concentration, preferring to go after higher calorie nectar. By improving the rewards on offer, plants may benefit by encouraging the pollinators to spend longer visiting the plant, or to visit more flowers of the same species. Enhancing sugar levels when pollinators approach might help a plant save energy in the long run, and reduce the risk of nectar being degraded by microbes or stolen by ants. “Nectar can be a significant energy investment, and thus keeping a constantly high level of sugar can be wasteful,” says Hadany. How plants detect the sound of bees is unknown. However, using highly sensitive laser instruments, the researchers found that the evening primrose flowers vibrate when played recordings of bee or moth sounds. Hadany thinks that flowers may receive sound pressure in a similar way to ears. When petals were removed from flowers, they vibrated less when played the sound clips, suggesting petals may help receive or amplify pollinator sounds.
1-8-19 Why more female penguins are washing up dead in South America
Every year, thousands of penguins become stranded on South America's coast - with females three times more likely to wash up dead or injured than males. Now scientists from Japan and Argentina have concluded this is because female Magellanic penguins are migrating further north in search of food than their male counterparts.
1-7-19 Green darner dragonflies migrate a bit like monarch butterflies
Each annual migratory loop takes multiple generations. The monarch butterfly isn’t the only insect flying up and down North America in a mind-boggling annual migration. Tests show a big, shimmering dragonfly takes at least three generations to make one year’s migratory loop. Ecologist Michael Hallworth and his colleagues pieced together the migration of the common green darner, described December 19 in Biology Letters, using data on forms of hydrogen in the insects’ wings, plus records of first arrivals spotted by citizen scientists. The study reveals that a first generation of insects emerges in the southern United States, Mexico and the Caribbean from about February to May and migrates north. Some of those Anax junius reach New England and the upper Midwest as early as March, says Hallworth, of the Smithsonian Migratory Bird Center headquartered in Washington, D.C. Those spring migrant darners lay eggs in ponds and other quiet waters in the north and eventually die in the region. This new generation migrates south from about July until late October, though they have never seen where they’re heading. Some of these darners fly south in the same year their parents arrived and some the next year, after overwintering as nymphs. A third generation emerges around November and lives entirely in the south during winter. It’s their offspring that start the cycle again by swarming northward as temperatures warm in the spring. With a wingspan as wide as a hand, they devote their whole lives to flying hundreds of kilometers to repeat a journey their great-grandparents made.
1-5-19 Japan sushi tycoon pays record tuna price
A Japanese sushi boss has paid a record $3.1m (£2.5m) for a giant tuna at the first new year's auction in Tokyo's new fish market. Self-styled "Tuna King" Kiyoshi Kimura bought the 278kg (612lbs) bluefin tuna, which is an endangered species. He spent more than twice the previous record of $1.4m, which he paid in 2013. Wholesalers and sushi company owners often pay high prices for the best fish at the first pre-dawn auction of the new year. "I bought a good tuna," Mr Kimura told AFP after the auction. "The price was higher than originally thought, but I hope our customers will eat this excellent tuna." Mr Kimura has been the highest bidder at the new year auction for seven of the past eight years. (Webmaster's comment: What chance does wildlife have against the greed inspired by this!) On a normal day a similar sized fish would sell for around $60,000. Today's record is in part about status - and it creates a lot of publicity for Mr Kimura and his sushi empire. But it is also a reflection of the scarcity of large Pacific bluefin tuna. They are officially listed by the WWF (World Wildlife Fund) as an endangered species. In 2018 catches off the coast of Japan were significantly down, and since the middle of last year prices in Tokyo have climbed by more than 40%. (Webmaster's comment: Someday the last wild animal will be killed so the rich can eat it!)
1-4-19 Rabbits that don’t eat their own faeces are small and weak
Rabbits have a taste for their own faeces – and now we know why. The small mammals produce both soft and hard faeces, and will routinely eat the soft ones. It turns out that eating soft faeces helps the rabbits digest their food and gain weight at a healthy rate. To test what effect a faeces-containing diet has on rabbits, Ming Li at the Henan Agricultural University in China and his team raised two groups of New Zealand rabbits. Some were allowed to eat their own faeces freely and others wore a cone-shaped collar that stopped them from eating anything but the food they were given by the researchers. Previous work has shown that rabbits prohibited from eating faeces take in 15 to 22 per cent less microbial protein, as their digestive system may not be efficient enough to absorb nutrients quickly before food is expelled as waste. Rabbit faeces include a variety of microorganisms that may be required to populate the gut and aid in digestion. When Li’s team compared their two groups of rabbits after 90 days, they found that those that were prohibited from eating faeces had significantly lower body weight. Their weight gain over the three-month study was 32 per cent less than the rabbits without collars, even though both groups took in the same amount of food. The collared rabbits also had livers that weighed less than the livers of rabbits in the control group. Retinoic acid – formed from ingested vitamin A – is stored in the liver, and a lack of retinoic acid can lead to abnormal organ development. The team analysed the genes expressed in the livers of both groups of rabbits, and found that genes related to retinoic acid were less active in the rabbits that didn’t eat their own faeces. Collectively, this suggests that rabbits must ingest their faeces to develop a healthy liver – and ensure healthy organ development.
1-4-19 Japan’s plan to resume commercial whaling could actually help whales
Japan’s move is bad news for whales within its waters, but spells the end of high seas whaling, says Matthew Collis. As 2018 drew to a close, Japan used the cover of the holiday season to confirm that it will quit the International Whaling Commission (IWC) and “resume” commercial whaling. Of course, Japan has never really stopped. Since a ban on the practice came into force in 1986, Japan continued supplying its whale meat market under the guise of “scientific” whaling, slaughtering more than 15,000 animals in the intervening years. This supposed research has been repeatedly discredited, both by scientific panels set up by the IWC and by international courts and conventions. What has changed is that Japan now says it will withdraw from the Southern Ocean and hunt whales only in its own waters. That is welcome news for whales in the high seas, which will no longer be pursued for science that nobody respects and products that nobody needs. It is good news for legitimate science, too. The only whale science to take place in the Antarctic under the auspices of the IWC from next year will be non-lethal research via the multi-nation Southern Ocean Research Partnership. Japan’s departure will allow that work to continue without being overshadowed by a discredited programme. Japan’s announcement comes while its whaling fleet is killing whales in the Southern Ocean. Given it says it will end its Antarctic whaling when its withdrawal from the IWC comes into effect at the end of June, there is no reason for it to continue its “scientific” slaughter now. Instead, it should immediately withdraw its whaling fleet. The International Fund for Animal Welfare, where I work, expects conservation-minded members of the IWC to be demanding no less. Of course, Japan’s announcement is bad news for whales in Japanese waters. The country claims it will set catch limits in accordance with methods adopted by the IWC. What is more likely is it will develop its own version of the IWC method, one designed to produce catch quotas that meet domestic market needs and political imperatives, not the IWC’s sustainability criteria. It will be important for the international community to scrutinise these plans carefully when more detail is revealed.
1-4-19 A subterranean ecosystem
The ground beneath our feet is teeming with a diverse ecosystem that is almost double the size of all the life found in the world’s oceans. That’s the conclusion of 1,200 scientists who are nearing the end of a decade-long international project to examine the mysterious microbes that inhabit Earth’s subsurface, reports ScienceDaily.com. Researchers with the Deep Carbon Observatory gathered samples from hundreds of underground sites around the world—including diamond mines, 3-mile-deep boreholes, and underwater mud volcanoes. They calculated that the subterranean ecosystem could contain up to 25 billion tons of carbon—hundreds of times more than is woven into all 7.5 billion humans. Some 70 percent of the microbes on Earth are thought to live in the subsurface, including many organisms that are unlike anything above ground. Some breathe uranium and expel the waste as crystals, while others live in deep-sea hydrothermal vents with temperatures of 250 degrees Fahrenheit. “It’s probably reasonable to assume that the subsurface of other planets and their moons is habitable,” says Rick Colwell, a professor from Oregon State University, “especially since we’ve seen here on Earth that organisms can function far away from sunlight.”
1-3-19 Fetal sharks may look for food by swimming around inside their mothers
Sharks are agile swimmers, even before they are born. Underwater ultrasound scans have revealed that shark fetuses can swim from one of their mother’s twin uteruses to the other. Most mammal fetuses remain sedentary in their mothers’ wombs. Like mammals, some sharks give birth to live young instead of eggs, leading scientists to assume that fetal sharks probably stay put too. Taketeru Tomita at Okinawa Churashima Research Center in Japan and his colleagues have now discovered that this isn’t the case. Using a newly developed underwater ultrasound machine, the team monitored three pregnant tawny nurse sharks living in the Okinawa Churashima Aquarium. Female sharks have two connected uteruses, aligned side by side. Conducting 44 ultrasound scans throughout the sharks’ pregnancies, the team found that the number of fetuses in each of a shark’s two uteruses kept changing, from two months into pregnancy onwards. This suggests that the fetal sharks swim from one uterus to another. To swim between uteruses, a fetus must navigate through a tight, U-shaped bend. The ultrasound footage showed one fetal shark wiggling its tail as it moved from one uterus to another at a speed of 8 centimetres per second. It is unclear why these animals begin swimming inside their mother before birth, but Tomita thinks they may be looking for food. Like some other shark species, fetal tawny nurse sharks are known to feed on undeveloped eggs. It is possible that fetal sharks move between uteruses in search of more eggs to eat. Tomita thinks the eggs eaten in the womb are probably unfertilised, but we don’t know for sure.
1-2-19 Black-haired monkeys in Costa Rica are suddenly turning blonde
One group of monkeys is going through an unexpected transition – their coats are changing rapidly from charcoal black to creamy yellow. Hair colour in primates is controlled by melanin. It comes in two forms: eumelanin, which is responsible for brown and black hues, and pheomelanin, which produces yellow and red tones. The mix of melanin in an animal’s skin and hair is determined by DNA, so the natural hair colour of individuals belonging to the same species should remain relatively fixed. That’s why Ismael Galván at the Doñana Biological Station in Spain and his colleagues were so surprised when they spotted several mantled howler monkeys (Alouatta palliata) in Costa Rica that have patches of blonde hair on their limbs and tails. Normally, these monkeys have a fully black coat. To find out what happened, the team collected samples of black hair and blonde hair from a mantled howler monkey. Galván found its blonde hair contains pheomelanin instead of the eumelanin that the monkeys usually produce. “I don’t know any precedent example of a conspicuous colour change in a given population of a wild animal,” says Galván. Back in 2001, none of the mantled howler monkeys in Costa Rica had blonde hair. In 2013, a dozen mantled howler monkeys were spotted with yellow hair on the tip of their limbs and tails. The most recent observation suggests that there are at least 21 individuals with the yellow colouration. Moreover, the patches are increasing in size – and two of the monkeys have a fully yellow coat with no black hair.
1-1-19 How an ant colony remembers
The whole is greater than the sum of its parts. Like a brain, an ant colony operates without central control. Each is a set of interacting individuals, either neurons or ants, using simple chemical interactions that in the aggregate generate their behavior. People use their brains to remember. Can ant colonies do that? This question leads to another question: What is memory? For people, memory is the capacity to recall something that happened in the past. We also ask computers to reproduce past actions — the blending of the idea of the computer as brain and brain as computer has led us to take "memory" to mean something like the information stored on a hard drive. We know that our memory relies on changes in how much a set of linked neurons stimulate each other; that it is reinforced somehow during sleep; and that recent and long-term memory involve different circuits of connected neurons. But there is much we still don't know about how those neural events come together, whether there are stored representations that we use to talk about something that happened in the past, or how we can keep performing a previously learned task such as reading or riding a bicycle. Any living being can exhibit the simplest form of memory, a change due to past events. Look at a tree that has lost a branch. It remembers by how it grows around the wound, leaving traces in the pattern of the bark and the shape of the tree. You might be able to describe the last time you had the flu, or you might not. Either way, in some sense your body "remembers," because some of your cells now have different antibodies, molecular receptors, which fit that particular virus. Past events can alter the behavior of both individual ants and ant colonies. Individual carpenter ants offered a sugar treat remembered its location for a few minutes; they were likely to return to where the food had been. Another species, the Sahara Desert ant, meanders around the barren desert, searching for food. It appears that an ant of this species can remember how far it walked, or how many steps it took, since the last time it was at the nest. A red wood ant colony remembers its trail system leading to the same trees, year after year, although no single ant does. In the forests of Europe, they forage in high trees to feed on the excretions of aphids that in turn feed on the tree. Their nests are enormous mounds of pine needles situated in the same place for decades, occupied by many generations of colonies. Each ant tends to take the same trail, day after day, to the same tree. During the long winter, the ants huddle together under the snow. The Finnish myrmecologist Rainer Rosengren showed that when the ants emerge in the spring, an older ant goes out with a young one along the older ant's habitual trail. The older ant dies, and the younger ant adopts that trail as its own, thus leading the colony to remember, or reproduce, the previous year's trails.