Feb 8, 2014
Pacific salmon inherit magnetic sense of direction
A team of scientists last year presented evidence of a correlation between the migration patterns of ocean salmon and Earth's magnetic field, suggesting it may help explain how the fish can navigate across thousands of miles of water to find their river of origin.
This week, scientists confirmed the connection between salmon and the magnetic field following a series of experiments at the Oregon Hatchery Research Center in the Alsea River basin. Researchers exposed hundreds of juvenile Chinook salmon to different magnetic fields that exist at the latitudinal extremes of their oceanic range. Fish responded to these "simulated magnetic displacements" by swimming in the direction that would bring that toward the center of their marine feeding grounds.
The study, which was funded by Oregon Sea Grant and the Oregon Department of Fish and Wildlife, will be published this month in the forthcoming issue of Current Biology.
"What is particularly exciting about these experiments is that the fish we tested had never left the hatchery and thus we know that their responses were not learned or based on experience, but rather they were inherited," said Nathan Putman, a postdoctoral researcher at Oregon State University and lead author on the study.
"These fish are programmed to know what to do before they ever reach the ocean," he added.
To test the hypothesis, the researchers constructed a large platform with copper wires running horizontally and vertically around the perimeter. By running electrical current through the wires, the scientists could create a magnetic field and control the both the intensity and inclination angle of the field. They then placed 2-inch juvenile salmon called "parr" in 5-gallon buckets and, after an acclimation period, monitored and photographed the direction in which they were swimming.
Fish presented with a magnetic field characteristic of the northern limits of the oceanic range of Chinook salmon were more likely to swim in a southerly direction, while fish encountering a far southern field tended to swim north. In essence, fish possess a "map sense" determining where they are and which way to swim based on the magnetic fields they encounter.
"The evidence is irrefutable," said co-author David Noakes of OSU, senior scientist at the Oregon Hatchery Research Center and the 2012 recipient of the American Fisheries Society's Award of Excellence. "I tell people: The fish can detect and respond to the Earth's magnetic field. There can be no doubt of that."
Not all of the more than 1,000 fish swam in the same direction, Putman said. But there was a clear preference by the fish for swimming in the direction away from the magnetic field that was "wrong" for them. Fish that remained in the magnetic field of the testing site -- near Alsea, Ore. -- were randomly oriented, indicating that orientation of fish subjected to magnetic displacements could only be attributable to change in the magnetic field.
"What is really surprising is that these fish were only exposed to the magnetic field we created for about eight minutes," Putman pointed out. "And the field was not even strong enough to deflect a compass needle."
Putman said that salmon must be particularly sensitive because the Earth's magnetic field is relatively weak. Because of that, it may not take much to interfere with their navigational abilities. Many structures contain electrical wires or reinforcing iron that could potentially affect the orientation of fish early in their life cycle, the researchers say.
"Fish are raised in hatcheries where there are electrical and magnetic influences," Noakes said, "and some will encounter electrical fields while passing through power dams. When they reach the ocean, they may swim by structures or cables that could interfere with navigation. Do these have an impact? We don't yet know."
Putman said natural disruptions could include chunks of iron in Earth's crust, though "salmon have been dealing with that for thousands of years."
Read more at Science Daily
Red skies discovered on extreme brown dwarf
Brown dwarfs straddle the line between stars and planets. They are too big to be considered as planets; yet they do not have sufficient material to fuse hydrogen in their cores to fully develop into stars. They are midway in mass between stars, like our Sun, and giant planets, like Jupiter and Saturn. Sometimes described as failed stars, they do not have an internal source of energy -- so they are cold and very faint, and keep on cooling over time.
The brown dwarf, named ULAS J222711-004547, caught the researchers' attention for its extremely red appearance compared to "normal" brown dwarfs. Further observations with the VLT (Very Large Telescope) in Chile and the use of an innovative data analysis technique have shown that the reason for its peculiarity is the presence of a very thick layer of clouds in its upper atmosphere.
Federico Marocco, who led the research team from the University of Hertfordshire, said: "These are not the type of clouds that we are used to seeing on Earth. The thick clouds on this particular brown dwarf are mostly made of mineral dust, like enstatite and corundum.
"Not only have we been able to infer their presence, but we have also been able to estimate the size of the dust grains in the clouds."
The size of the dust grains influences the colour of the sky. In a similar way that the old saying of "Red sky at night, shepherd's delight. Red sky in the morning, shepherd's warning" is used at sunrise and sunset to indicate the changing weather, a red sky on the brown dwarf suggests an atmosphere loaded with dust and moisture particles. If our morning skies are red, it is because clear skies to the east permit the sun to light the undersides of moisture-bearing clouds coming in from the west. Conversely, in order to see red clouds in the evening, sunlight must have a clear path from the west in order to illuminate moisture-bearing clouds moving off to the east. However, the recently discovered brown dwarf ULAS J222711-004547 has a very different atmosphere where the sky is always red.
The giant planets of the Solar System, like Jupiter and Saturn, show various cloud layers including ammonia and hydrogen sulphide as well as water vapour. The atmosphere observed in this particular brown dwarf is hotter -- with water vapour, methane and probably some ammonia but, unusually, it is dominated by clay-sized mineral particles.
Getting a good understanding of how such an extreme atmosphere works will help us to better understand the range of atmospheres that can exist.
Dr Avril Day-Jones, from the University of Hertfordshire's Centre for Astrophysics Research, who contributed to the discovery and analysis said: "Being one of the reddest brown dwarfs ever observed, ULAS J222711-004547 makes an ideal target for multiple observations to understand how the weather is in such an extreme atmosphere."
Read more at Science Daily
Feb 7, 2014
Do Some Animals Get a Taste for Human Blood?
Recent killings by a tiger in northern India reveal how circumstances can cause predators to develop a taste for humans.
Certain animal predators may become serial killers of people, suggest animal experts and reports of multiple deaths inflicted by particular animals. In this case, a tigress is said to have killed nine people -- so far -- in a densely forested area near Jim Corbett National Park in Uttar Pradesh. Hunters are trying to track the animal in the forest, either to capture, but most likely to kill it.
"They do get a taste for humans," conservationist Belinda Wright from the Wildlife Protection Society of India told AFP. "But I think (attacks happen) more because we're very easy prey. As a tiger gets older, or is disabled in some way, we're just very, very easy as we bumble around on our two legs."
This tiger, one of about 200 living in the park, has terrorized local residents. Children can't venture far from their houses and farmers have stopped sleeping in their fields for fear of attack.
George Burgess, director of the Florida Program for Shark Research, told Discovery News: "It is not out of the realm of possibility that some individual animals may learn to target humans. Large cats may come to view us as easy pickings under some circumstances."
A growing taste for salt might explain the deaths.
Maheshwor Dhakal of the Department of National Parks and Wildlife Conservation in Kathmandu believes that as soon as leopards and other big cats start to prey upon humans, it is difficult to get them to stop.
"Since human blood has more salt than animal blood, once wild animals get the taste of salty blood, they do not like other animals like deer," Dhakal told CNN.
But developing a taste for humans, or anything, requires a learning process based on past experience. That isn't possible unless the predator can frequently encounter the "food source."
Johnny Rodrigues, chairman for the Zimbabwe Conservation Task Force, has told Discovery News that wild animals are often reported as being in urban areas "possibly because humans are encroaching more and more into areas previously reserved for wildlife, resulting in the destruction of their habitat."
In terms of big cats, the usual problem concerns deadly encounters with cows, sheep and other livestock. An animal that goes after humans is rare.
Burgess said that he knows of only two instances where individual sharks have repeatedly attacked humans. Both occurred in waters off of Egypt. In each instance, humans were to blame, although indirectly.
He explained that vessels from Australia and New Zealand were transporting live sheep to Egypt, since sheep are sacrificed there for a religious holiday.
"Sheep that died on the ships were tossed overboard," Burgess said. "Sheep defecate and urinate, so that waste was also being washed overboard. The result was a chum trail that likely went all the way from New Zealand to the Red Sea."
He explained that vessels from Australia and New Zealand were transporting live sheep to Egypt, since sheep are sacrificed there for a religious holiday.
"Sheep that died on the ships were tossed overboard," Burgess said. "Sheep defecate and urinate, so that waste was also being washed overboard. The result was a chum trail that likely went all the way from New Zealand to the Red Sea."
An oceanic whitetip shark and a mako shark appear to have followed this trail, winding up in more shallow water used for human recreation. Without sheep or other prey to eat, the sharks went after humans.
"So it's highly unusual for an individual shark or other animal to repeatedly prey upon humans, but it can happen," Burgess said.
Such encounters remind that humans were not always at the top of the food chain.
Kirsten Jenkins, a University of Minnesota anthropologist, explained that an early ape called Proconsul -- thought to have been an ancestor to both modern humans and chimpanzees -- was good eats for numerous predators.
"I have observed multiple tooth pits and probable beak marks on these fossil primates, which are direct evidence for creodonts and raptors consuming these primates," Jenkins told Discovery News.
Read more at Discovery News
Prehistoric Carnivore Had 'Steak Knife' Teeth
Dimetrodon lived at what are now the southwestern United States and parts of Europe between 298 million and 272 million years ago. (The first dinosaurs evolved from other animals some 40 million years later.)
Based on the new study, published in Nature Communications, we know that Dimetrodon was not afraid to bite off more than it could chew.
Its sharp, serrated teeth allowed Dimetrodon to rip into prey much larger than itself. Not surprisingly, this ravenous carnivore was at the top of the terrestrial food chain during its existence in the Early Permian Period.
“The steak knife configuration of these teeth and the architecture of the skull suggest Dimetrodon was able to grab and rip and dismember large prey,” co-author Robert Reisz, a University of Toronto Mississauga biologist, said in a press release.
“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton," he continued. "We already know from fossil evidence which animals existed at that time but now, with this type of research, we are starting to piece together how the members of these communities interacted."
Based on other known animals living at the time of Dimetrodon's existence, the toothy predator probably hunted prey such as large fish, aquatic amphibians, and certain land animals, including reptiles. It might have also snacked on insects that were around then.
Reisz and graduate student Kirstin Brink, who led the study, used high tech equipment, such as a scanning electron microscope (SEM), to get an ultra close-up look at Dimetrodon's teeth.
In addition to its ziphodont (a.k.a. steak knife) teeth, this carnivore also sported cusps -- teeth with raised points on the crown -- which are dominant in mammals.
It's now thought that this over 13-foot-long very ancient animal was a forerunner to mammals. That’s amazing to consider, given the reconstruction of Dimetrodon with its Spinosaurus-type "sail" on its back, turtle-looking head and more.
Read more at Discovery News
Earliest Human Footprints Outside Africa Found in Britain
Researchers discovered the footprints, which were left by both adults and children, in ancient estuary mud at Happisburgh in Norfolk, eastern England.
The only older footprints found so far are at Laetoli in Tanzania, at about 3.5 million years old, and at Ileret and Koobi Fora in Kenya at about 1.5 million years, they added.
"This is an extraordinarily rare discovery," said Nick Ashton of the British Museum, who led the research team, which also involved the National History Museum and Queen Mary University London.
The discovery came at an archaeological site that has yielded several previous discoveries of stone tools and fossil bones, including mammoth remains.
The researchers found the prints at low tide when waves washed away much of the beach sand to expose the silt below.
"At first we weren't sure what we were seeing but as we removed any remaining beach sand and sponged off the seawater, it was clear that the hollows resembled prints, perhaps human footprints, and that we needed to record the surface as quickly as possible before the sea eroded it away," Ashton said.
The group of early humans that left the footprints appeared to have consisted of at least one male and several smaller people believed to be females and youngsters, the researchers said.
"They are clearly a family group rather than a hunting party," said Ashton.
Analysis of the prints found that they were from a "range of adult and juvenile foot sizes" equating to modern shoe sizes of up to British 7 or 8 (US 8 or 9, European 41 or 42).
The researchers estimated that the height of the ancient humans who left the prints varied from about 0.9 meters to over 1.7 meters (2'11" to 5'6"), not far off the height of modern humans.
They were dated at 800,000 years old partly on the basis of the site's geological position beneath glacial deposits, but also because the fossils there come from now-extinct types of mammoth and horse and early forms of vole that were alive at that time.
Read more at Discovery News
The Bird That Does Unbelievable Impressions of Chainsaws, Car Alarms
Charles Darwin hated the peacock — hated it — at one point writing that he was simply sickened by its ostentatious feathers. He couldn’t for the life of him figure out why a creature would essentially beg to be hunted, seemingly in wanton disregard of his new theory of evolution, which is about the survival (not the evisceration) of the fittest.
The answer, Darwin eventually realized, is the principle of sexual selection. With its glorious plumage, the peacock is essentially saying to the peahen, “I’m healthy, and also I might have a bit of an ego problem.” It’s a drive so strong that it outweighs the risk of predation and justifies the tremendous energy the peacock puts into growing the feathers, not to mention lugging them around.
But sexual selection is far from a solely visual process. Behold the superb lyrebird, whose calls are surely the most impressive in the animal kingdom. It has the uncanny ability to perfectly mimic the sounds of the Australian forests it calls home, from camera shutters to other bird species to chainsaws, kinda like that guy from Police Academy with the funny voices, only it can’t carry a gun.
Just watch the video above. It’s real. I know because David Attenborough hosts it, and David is legit. This behavior is particularly common in captivity, where lyrebirds are inundated with decidedly unnatural sounds. And check out the second video below of a lyrebird in Australia’s Adelaide Zoo. It not only pulls off the din of a drill and hammer strikes, but the tone changes as a nail is driven home, guaranteeing that zoo employees will be annoyed by construction long after the construction itself is finished.
Physiologically, what could be driving this incredible mimicry? What makes the lyrebird so adept at impersonation? Well, according to behavioral ecologist Anastasia Dalziell of the Australian National University, we don’t really know yet. We can assume the lyrebird must have excellent hearing and memory, but what makes it so special biologically hasn’t been studied at length.
What we do know is that the lyrebird is a kind of songbird, producing sound with a vocal organ roughly equivalent to our larynx called a syrinx. (Syrinx, by the way, is Greek for “panpipe” and the name of a wood nymph who fled from the advances of Pan, who was a bit of a jackass. Beseeching assistance from water nymphs at a river’s edge, she was turned into reeds, which Pan chopped to pieces and fashioned into a flute. So … yeah.)
With lyrebirds, “it is true that their syrinx is slightly different in structure than most other songbirds,” Dalziell said in an email to WIRED. “For example, it has fewer syringeal muscles, but exactly how the structure of the syrinx allows it to produce so many sounds is not yet clear.” Strangely, notes Dalziell, having more muscles in the syrinx typically corresponds with greater vocal complexity — but the ultra-talkative lyrebirds (and parrots, as it happens) are exceptions to this rule.
In the wild, males will not only flawlessly imitate some 20 different species of birds, but multiple calls from each. They’re particularly fond of imitating Australia’s famous laughing kookaburras, and Dalziell has heard them mimicking the wing beats of small birds jetting through the forest understory. Up to 80 percent of a lyrebird’s song can consist of such mimicry, according to Dalziell, and “males imitate most often during the breeding season, particularly when females are fertile, so in this species there is strong evidence that for males mimicry is sexually selected.”
The females aren’t just looking for the best crooner, but also the best dancer and the best-dressed. So, basically, the avian opposite of me. This is where the lyrebird’s sexual dimorphism — the often dramatically different body types between females and males of a species, like in peafowl — becomes abundantly clear.
“Males have elaborate plumage, dance displays, and songs, while females are visually cryptic and a lot quieter,” said Dalziell. “Females are very independent: They defend their own territory and care for the young all by themselves (leaving males a lot of time to prance about).”
And prance about they do, in fairly remarkable fashion. During the breeding season, males clear space and build several round mounds of dirt in the forest, which they will boldly defend from other males (hey, it’s not like mounds of dirt just grow on trees). When a female takes an interest, the male will approach her with his magnificent tail slung over his head, then back up to one of the mounds.
If she follows, she’s treated to one of the more bizarre mating rituals on the planet, which you can watch below. “During these sexual displays,” said Dalziell, “male superb lyrebirds coordinate song with dance so that each different song is accompanied by a unique choreography, creating a display of a level of sophistication previously known only in humans.”
This is an extremely structured performance that Dalziell breaks into four parts, A through D. The first bit is “a laser gun-like song accompanied by a side-step, followed by a middle section of two alternating songs (B and C), followed by a ‘recapitulation’ of song A before a ‘coda’ of song D.” It’s seriously epic, like, Led Zeppelin at the Royal Albert Hall in 1970 epic.
So just as humans “waltz” to waltz music and “salsa” to salsa music, Dalziell says, “so lyrebirds step sideways with their tail spread out like a veil to song A (which sounds like a 1980s video-arcade game), but jump and flap their wings with their tail in a mohawk position while singing song C (a quiet song that sounds like ‘plinkety-plinkety-plinkety’).”
Only the fittest males, with the most impressive feathers and songs and dances, are allowed to mate and pass on their genes. This will ideally produce equally, if not more, incredible attributes in their offspring. “All females need from males is sperm,” said Dalziell, “and we know from other species of birds that this scenario can lead to intense competition among males for access to females, sometimes resulting in elaborate attempts to impress females.”
Darwin’s idea that females can drive evolution in this way wasn’t exactly popular with his critics (of which there were more than a few) in the 19th century. Not only was it preposterous for female humans to — heaven forbid — make choices, but the same went for all female creatures, even dogs and cats and stuff. But such selection is how the males and females of a given species will physically diverge over countless generations when faced with an abundance of competition.
Interestingly, though, elsewhere in nature the near lack of competition will produce the same effect, only in the sexual reverse. Take, for instance, the deep sea anglerfish, whose fearsome, gargantuan females positively dwarf males, which bite and fuse to the ladies to serve as a ready supply of sperm for the rest of their miserable lives.
Read more at Wired Science
Feb 6, 2014
Bumblebees Can Fly Higher Than Mount Everest
Bumblebees cannot survive the freezing conditions of Mt. Everest's peak. But researchers based at the University of California, Berkley simulated the low oxygen and low air density conditions of such high elevations to determine the limits of the bumblebee's flight capacity, and found the bees were capable of staying afloat at remarkably inhospitable elevations.
The team traveled to a mountain range in western China and collected six male bumblebees of the species Bombus impetuosus at about 10,660 feet (3,250 meters). The species is considered alpine, because it lives at alpine elevations, but it doesn't differ very much from similar species that live closer to sea level.
The researchers placed the bees in clear, sealed boxes and experimentally adjusted the oxygen levels and air density using a hand pump to simulate increasing elevation, while keeping temperature constant.
All of the bees were capable of flying in conditions equivalent to 13,000 feet (4,000 m), and some even made it past 30,000 feet (9,000 m) — the height of the peak of Mount Everest — the team reported Tuesday (Feb. 4) in the journal Biology Letters.
The team used a video camera to study how wing beat patterns changed to compensate for the thinner air and lower oxygen concentrations of high elevations, hypothesizing that the bees would either need to beat their wings faster or swoop them wider to keep their bodies afloat. The researchers found that, instead of beating their wings faster, the bees increased the angle at which they extended their wings with each beat, reaching closer to their heads and abdomens each time. This action increased the amount of air that they swooped, helping to boost their bodies up.
The findings suggest that bumblebees are not limited by flying capacity when searching for places to settle their colonies, but rather by something else, such as the availability of the flower nectar they feed on, study lead author Michael Dillon, who now works at the University of Wyoming, told Live Science. This could bode well for alpine bumblebees in the future, Dillon said, as climate change may force animals up to higher elevations than they once inhabited due to warming conditions at lower elevations.
Read more at Discovery News
Dwarf Whales, Twin-Tusked Walrus Once Swam West Coast
Walruses with short, twin tusks lounged on the beaches. Dwarf baleen whales, relatives of blue whales, filtered tiny creatures from the sea water. A dentally-deranged porpoise with a “chin” longer than its upper jaw shared the sea with the dwarf whales.
Primitive forms of porpoise and a dolphin related to the extinct Chinese river dolphin also lived in the region.
Along with the strange extinct beasts, modern-type species also dwelt in the region, including northern fur seals and right whales, during the late Miocene and Pliocene Epochs, which ended approximately 2.5 million years ago.
Robert Boessenecker, geology doctoral student at the university of Otago, recently published a description of the fossilized remains of the ancient northern Pacific marine animals in the journal Geodiversitas.
“The mix of marine mammals I ended up uncovering was almost completely different to that found in the North Pacific today, and to anywhere else at that time,” Boessenecker said in a press release. “At the same time as this eclectic mix of ancient and modern-type marine mammals was living together, the marine mammal fauna in the North Atlantic and Southern Ocean were already in the forms we find today.”
Read more at Discovery News
New Deep Diving Whale Discovered
The first finding of Mesoplodon hotaula came in 1963 when a 4.5 meter-long (15-foot) female washed up on the beach of Sri Lanka. Originally, the animal was described as a new species, but taxonomists later argued that the animal belonged to an already known variety, the ginko-toothed whale (Mesoplodon ginkgodens).
Since then, corpses of the whale were found on Kiribati, Palmyra Atoll, the Maldives, and the Seychelles. Genetic analysis of the whales and examination of their physical characteristics have now confirmed that Mesoplodon hotaula deserves classification as a distinct species of beaked whale. The journal Marine Mammal Science published the description of the resurrected species.
The animals swim in the deep waters off the continental shelves. They rank among Earth’s champions divers. In the Journal of Experimental Biology, scientists recorded one species, Cuvier’s beaked whale, diving to 1,888 meters (6,194 feet) and staying down for 85 minutes.
Read more at Discovery News
'Missing' Evolutionary Link for Compact Galaxies Found
My first astronomy professor put it this way: Imagine that you are part of an alien race, come down to Earth to study humanity. But, you’ve only got a few minutes to fly around the world and collect your data. How might you try and understand the life cycle of a human being? You’d have lots of pictures of small people, some so small to be almost helpless. Then there are lots of big people, too. People come in all shapes, sizes, and colors. But with that snapshot of humanity, you have to piece together the life stages of a human.
It is like this with galaxies in the Universe. We see big galaxies and small galaxies, spirals and ellipticals and irregular galaxies, too. We’ve had to put together the history of these galaxies as best we can without actually having the millions and billions of years to watch them grow up. Sometimes we get it dead wrong, as in the early 20th century it was thought that elliptical galaxies can eventually flatten out to become disks and spirals. We now know that larger galaxies are built in the mergers of smaller galaxies, but even in that paradigm there is room for diversity.
This method of galaxy building takes quite a bit of time, so you only expect to see larger galaxies nearby but not far away due to lookback time. However, some galaxies just won’t fit that mold. Some seem to defy a simple explanation.
In order to have these in existence, there must have been an incredibly powerful galaxy-building epoch even earlier, at redshifts 3 to 6, or 1 to 2 billion years after the Big Bang. Such galaxies would be full of dust and gas that would obscure their optical light, as well as being redshifted to longer wavelengths by their distance.
Such a population of galaxies has finally been uncovered and categorized by a group of astronomers led by Sune Toft, of the DARK Cosmology Center at the Niels Bohr Institute, University of Copenhagen. In a paper that contains data from many telescopes around the world and in space — including Hubble, Spitzer, Herschel, Keck, the Very Large Array, the Sub-Millimeter Array, and many more — they characterize the sample of submillimeter-emitting gas-rich galaxies that exist in the early Universe and find that it has just the right characteristics to merge and make the giant ellipticals that are “red and dead” 10 billion years ago, and even more so today.
Read more at Discovery News
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