Record-Breaking Whale Stays Underwater for 3 Hours and 42 Minutes

On September 25, 2020September 24, 2020 By A.P.In UncategorizedLeave a comment

By George Dvorsky

Marine biologists are astonished after a Cuvier’s beaked whale held its breath for nearly four hours during a deep dive. The unexpected observation shows there’s much to learn about these medium-sized whales.

Scientists from Duke University and the Cascadia Research Collective recorded the unbelievable dive during field observations off the coast of Cape Hatteras, North Carolina, in 2017. In the first of two epic dives, the Cuvier beaked whale, wearing tag ZcTag066, stayed underwater for nearly three hours. A week later, the whale outdid itself, holding its breath for a bewildering three hours and 42 minutes.

“We didn’t believe it at first, because these are mammals after all, and any mammal spending that long underwater just seemed incredible,” Nicola Quick, the lead author of the new study and a biologist at Duke University, said in an email.

The record-breaking observations occurred in the midst of a five-year survey, in which Quick and her colleagues were measuring the time it takes Cuvier beaked whales (Ziphius cavirostris) to perform their deep foraging dives. During these dives, the whales venture to depths exceeding 9,800 feet (3,000 meters) and hunt squid and deep-sea fish. Unfortunately, the two recordings of ZcTag066 had to be excluded from the researchers’ primary data set “because they were recorded 17 and 24 days after a known [one-hour] exposure to a Navy mid-frequency active sonar signal,” as the authors wrote in the study, adding that these two extreme dives “are perhaps more indicative of the true limits of the diving behaviour of this species.” It’s possible the exposure to sonar might have altered the whale’s normal diving habits, but the researchers don’t know.

Going into the study, the scientists had estimated a maximum length of 33 minutes for the deep dives, after which time the whales need to resurface and gulp some precious atmospheric oxygen, or resume “anaerobic respiration,” in the parlance of the researchers. The team conducted field observations to test this assumption and to measure the length of time it takes for these toothed whales to recover once at the surface. Details of their work were published today in the Journal of Experimental Biology.

Cuvier’s beaked whales are elusive and skittish, having developed fascinating strategies to avoid predators, namely orcas. Thus, it was a challenge for the team to place their satellite-linked tags onto the whales.

“Because the animals spend so little time at the surface, we needed calm seas and experienced observers to look for them,” said Quick in a press release, adding that the “average period they spend at the surface is about two minutes, so getting a tag on [them] takes a dedicated crew and a manoeuvrable vessel.”

The researchers managed to tag 23 individuals, with field observations ongoing from 2014 to 2018. In total, the scientists recorded more than 3,600 foraging dives, the median duration of which was clocked at 59 minutes. The shortest dives lasted just 33 minutes, but the longest dive (excluding ZcTag066’s) was recorded at 2 hours and 13 minutes.

With this data in hand, the researchers had to revise their models. They re-visited the breath-holding patterns and abilities of other aquatic mammals, which led to a new estimate of 77.7 minutes. This obviously still fell considerably short of their field observations, as 5% of dives exceeded this apparent limit.

Clearly, the scientists are missing something about these whales and the unique abilities that allow for their extended stays beneath the water. This sad fact was driven home even further when the team analyzed the whales’ recovery time, that is, the time spent on the surface after a long foraging dive in preparation for a subsequent dive.

It stands to reason that, after a super-long dive, a Cuvier’s beaked whale might want to chill on the surface for a bit to replenish its oxygen supply and rest its weary muscles. Weirdly, this assumption did not jibe with the field observations, as no clear pattern emerged from the data. For example, a whale that dove for 2 hours needed just 20 minutes of rest before it went back for more, while another whale, after diving for 78 minutes, stayed on the surface for 4 hours before foraging again. The new study raises more questions than it answers.

We asked Quick how it’s possible for these mammals to stay underwater for so long.

“These animals are really adapted to diving, so they have lots of myoglobin in their muscles, which helps them to hold more oxygen in their bodies,” she replied. “They are also able to reduce their energy expenditure by being streamlined to dive, and we think reducing their metabolic rate. It’s likely they have many other adaptations as well that we still don’t fully understand, such as being able to reduce their heart rates and restrict the movement of blood flow to tissues.”

As to why some some of the dives lasted so long, the authors said the whales may have been enjoying their time in areas rich in food or reacting to a perceived threat, such as a noise disturbance (U.S. Navy, we’re looking at you).

An encouraging aspect of this study is how much there is still to learn about these aquatic mammals. Clearly, it’s a case of biology exceeding our expectations, which can only be described as exciting.

https://gizmodo.com/record-breaking-whale-stays-underwater-for-mind-bending-1845155205

Ice Age Cave Bear Found Exquisitely Preserved in Siberian Permafrost

On September 16, 2020September 16, 2020 By A.P.In UncategorizedLeave a comment

By George Dvorsky

Reindeer herders working on Bolshoy Lyakhovsky Island in arctic Russia have stumbled upon an incredibly well-preserved cave bear, in what scientists say is a discovery of “world importance.”

When it comes to studying extinct cave bears, paleontologists have traditionally dealt with scattered bones and the odd skull. That’s why this new discovery is so important, as the body of the adult cave bear is “completely preserved” with “all internal organs in place including even its nose,” as scientist Lena Grigorieva explained in a North-Eastern Federal University (NEFU) press release describing the specimen. The finds are of “great importance for the whole world,” she added.

The carcass—now the only known fully intact adult cave bear—was discovered by reindeer herders on the island of Bolshoy Lyakhovsky, which is located in arctic Russia between the Laptev Sea and the East Siberian Sea. Bolshoy Lyakhovsky is the largest of the Lyakhovsky Islands—a part of the New Siberian Islands archipelago.

Cave bears (Ursus spelaeus) went extinct just prior to the end of the last ice age some 15,000 years ago, though possibly as early as 27,800 years ago. Cave bears and modern bears diverged from a common ancestor around 1.2 million to 1.4 million years ago. They were quite large, weighing upwards of 1,540 pounds (700 kg), and were possibly omnivorous.

A preliminary estimate places the age of the newly discovered cave bear at between 22,000 and 39,500 years old. This large window needs to be constrained, and that’ll hopefully be accomplished by a radiocarbon analysis, as senior researcher Maxim Cheprasov from the Mammoth Museum laboratory in Yakutsk explained in the NEFU press release.

The remains will be studied by NEFU researchers in Yakutsk, along with Russian colleagues and international collaborators who will be invited to join the study. Possibilities for research are wide open: isotopic analysis of teeth could point to diet and geographical range; DNA analysis could offer new insights into its evolutionary history and unique genetic traits; and an analysis of its stomach contents could likewise shed light on its diet. It would be good to know, for example, if this beast was an obligate herbivore or an opportunistic omnivore like the modern brown bears it resembles.

In a separate but related discovery, a well-preserved cave bear cub was found on the mainland of Yakutia. Indeed, discoveries from arctic Russia seem to be increasing in frequency as the permafrost melts in Siberia. Recently, ice age lion cubs were found in Yakutsk, and an analysis of their DNA revealed more about the family tree of these extinct creatures.

https://gizmodo.com/ice-age-cave-bear-found-exquisitely-preserved-in-siberi-1845061915

Bees force plants to flower early by cutting holes in their leaves

On May 22, 2020 By A.P.In UncategorizedLeave a comment

By Alice Klein

Hungry bumblebees can coax plants into flowering and making pollen up to a month earlier than usual by punching holes in their leaves.

Bees normally come out of hibernation in early spring to feast on the pollen of newly blooming flowers. However, they sometimes emerge too early and find that plants are still flowerless and devoid of pollen, which means the bees starve.

Fortunately, bumblebees have a trick up their sleeves for when this happens. Consuelo De Moraes at ETH Zurich in Switzerland and her colleagues discovered that worker bumblebees can make plants flower earlier than normal by using their mouthparts to pierce small holes in leaves.

In a series of laboratory and outdoor experiments, the researchers found that bumblebees were more likely to pierce holes in the leaves of tomato plants and black mustard plants when deprived of food. The leaf damage caused the tomato plants to flower 30 days earlier than usual and the black mustard plants to flower 16 days earlier.

It is still a mystery how the leaf damage promotes early blooming. Previous studies have found that plants sometimes speed up their flowering in response to stressors like intense light and drought, but the effects of insect damage haven’t been studied much.

De Moraes and her colleagues were unable to induce early flowering by punching holes in the plant leaves themselves. This suggests that bees may provide additional cues that encourage flowering, like injecting chemicals from their saliva into the leaves when they pierce them. “We hope to explore this in future work,” she says.

Forest Fungi Ride Out Wildfires by Hiding Inside Plants

On April 23, 2020April 23, 2020 By A.P.In UncategorizedLeave a comment

by Annie Greene

After the Chimney Tops 2 Wildfire charred 11,000 acres of the Great Smoky Mountains National Park along the North Carolina–Tennessee state line in November 2016, rangers closed affected trails to visitors. Mycologists Andy N. Miller and Karen Hughes and their teams were an exception. Toting hard hats and sample collection kits, these scientists jumped at the opportunity to track down their research subjects: pyrophilous (“fire-loving”) fungi, which produce mushrooms prolifically after forest fires and then disappear as the forest recovers.

The severely burned areas of the Smokies were almost completely lifeless two months after the blaze, when the group first ventured into the affected zone. “The level of destruction was incredible,” recounts Hughes, a researcher at the University of Tennessee, Knoxville, in an email to The Scientist. “Everything I touched left black carbon on my hands. It was incredibly quiet.” Miller, who is based at the University of Illinois Urbana-Champaign, also noted a surreal lack of activity. “There’s nothing running around, no birds singing,” he says. To him, the site smelled “like a house had burned up.” When the researchers returned to their collection sites a few months later, however, their mushrooms of interest had risen from the ashes. Miller noticed that when these fungi surface, they do so en masse: “They’re less than a millimeter in diameter, but there’s a lot of them, and once you train your eyes, they’re just all over the place.”

The researchers were interested in documenting which species of pyrophilous fungi are present in the Smokies. They also wanted to test a theory about where the fungi go during the long periods between forest fires. Some fire-loving fungi are known to lie dormant in the dirt as spores or other heat-tolerant structures until post-fire soil conditions trigger growth and reproduction. Other species exist between burns in a vegetative state, aiding decomposition of dead organisms or interacting with tree roots. But many fire-loving fungi don’t fit into any of these categories. A new proposal, known as the body snatchers hypothesis, posits that some pyrophilous fungi hide out inside plants or lichens in between fires, nestling among host cells in a so-called endophytic or endolichenic state.

To test the hypothesis, the researchers traveled to the burn site every few months for more than a year to sample the soil, as well as the mosses and lichens that sprang up while the forest recovered. They also gathered specimens from unburned areas of the park for comparison. In May 2018, members of Miller’s lab began analyzing the samples they’d collected. DNA sequencing results identified a total of 22 pyrophilous fungal species in the Smokies. Of these, three species were present only in the soil, while the remaining 19 were found inside plant samples from burned and unburned areas, either exclusively or in addition to being found in the soil. In line with the body snatchers hypothesis, “almost all of our pyrophilous fungi were found as endophytes,” Miller says.

Mosses and lichens often live in difficult-to-reach places such as rock crevices and may be hardy enough to withstand minor flames, so fungi living inside these hosts could theoretically survive a low-intensity wildfire. But it’s still unclear how all of these organisms might persist through a moderate or severe burn, and how a fire-loving fungus would escape its host to recolonize a charred forest. Hughes has a hypothesis based on her observations at the burn site: “After the fire, I saw numerous tiny lichen fragments on the burned soil, as if they had been lofted into the air while trees were burning and settled on the ground after the fire,” she says. These burned plant fragments may inoculate the soil with the fungi they harbor, giving the fire-loving fungi a way into the dirt.

This is a feasible way for both a pyrophilous fungus and its host to rebound after a fire and maintain their relationship, according to Keith Clay, who studies plant-fungus interactions at Tulane University and was not involved with this study. “If [a moss fragment] lands in a good place, it can regenerate the whole plant,” says Clay. “If the endophyte is in that fragment, presumably it can just colonize these newly grown plants as well from the get-go.” Post-fire fungi may also acquire new hosts after a burn, Miller notes. One mushroom can produce millions of airborne spores that likely land on nearby mosses and lichens, germinate, and invade the tissues of these new hosts, he says.

To check whether their findings might apply to other forests, Miller and Hughes analyzed moss and lichen samples from other sites around the US. A handful of the fire-loving fungi identified in the Smokies were also present as endophytes in Indiana and Alaska. That result was surprising because “there was really no evidence that a fire had occurred in the last few years in those areas,” Miller says. “What are they doing there if they’re not waiting for a fire to come along?”

One possibility is that, while body snatching between fires, pyrophilous fungi use their plant hosts as nutrient sources, says Clay. He notes that many plants and fungi have mutualistic endophytic relationships, where the plant typically provides the fungus with “a home where they can live and sugars, carbon, from photosynthesis.” In return, the fungus often produces alkaloids that benefit the host. Yet for the pyrophilous fungi examined in this study, Clay says, “what they offer the plant is not clear.” Sydney Glassman, a microbial ecologist at the University of California, Riverside, who was not involved with the study, notes that in vitro assays using carbon isotopes could help uncover these trade-offs by revealing “nutrient transfer between the plants and the fungus.”

Miller and his team plan to examine the details of fungus-host interactions by recreating body snatching in the lab and conducting long-term field studies, he notes. After all, many forests where pyrophilous fungi live go for decades without fire, he says. “So how is that relationship maintained?”

https://www.the-scientist.com/notebook/forest-fungi-ride-out-wildfires-by-hiding-inside-plants-67326?utm_campaign=TS_DAILY%20NEWSLETTER_2020&utm_source=hs_email&utm_medium=email&utm_content=86856096&_hsenc=p2ANqtz-8BKRYRGs_fo90ZncO_fmihHmxcb7igfgKB79gkfdKckRdyLVHnViIWWELwSyNw7QIkAcI47O7ksk1iFQ0kJDaX39xITA&_hsmi=86856096

Hitchhiking red-billed oxpeckers warn endangered rhinos when people are nearby

On April 14, 2020April 13, 2020 By A.P.In UncategorizedLeave a comment

The black rhino was once the most populous rhino species on Earth, with an estimated 850,000 individuals roaming Africa. But poaching has devastated the species.

The red-billed oxpecker serves as an alarm bell for black rhinos, signaling nearby danger. The birds often eat pests like ticks from the backs of rhinos and other mammals, including livestock. Due to the practice of applying pesticides to livestock, the oxpecker has seen its numbers decline.

By Gloria Dickie

Red-billed oxpeckers hitching rides on the backs of black rhinos are a common sight in the African bush. The birds are best known for feeding from lesions full of ticks or other parasites on a rhino’s hide. But new research suggests that the relationship between the two species is much more mutualistic (SN: 10/9/02). Shouty and shrill oxpeckers can serve as an alarm bell, alerting black rhinos to the presence of people, scientists report April 9 in Current Biology. That could help the endangered animals evade poachers, the researchers propose.

“Rhinos are as blind as bats,” explains Roan Plotz, a behavioral ecologist at Victoria University in Melbourne, Australia. Even in close proximity, a rhino might struggle to notice lurking danger by sight. But the oxpecker easily can, unleashing a sharp call to warn of intruders.

In South Africa’s Hluhluwe–iMfolozi Park, Plotz and his colleague Wayne Linklater of California State University, Sacramento approached 11 black rhinos (Diceros bicornis) by foot on the open plain on 86 occasions. The team found that those rhinos with a red-billed oxpecker (Buphagus erythrorhynchus) tagging along were much better at detecting the researchers’ presence than those without.

“Rhinos without oxpeckers on their back were able to detect our approaches just 23 percent of the time whereas rhinos with oxpeckers detected them every single time,” Plotz says. Rhinos listening to an oxpecker’s heads-up also picked up on the approaching scientists from 61 meters away, more than twice as far as when the rhinos were alone.

All rhinos responded to the oxpeckers’ alarm calls by becoming vigilant — standing up from a resting position, for example — and turning to face downwind, their sensory blind spot. The rhinos then either ran away or walked downwind to investigate the potential danger.

Black rhinos were once the most numerous species of rhino in the world. But poaching for traditional Chinese medicine has devastated the species (SN: 11/17/79). Though poaching has slowed since its peak in 2015, just 5,500 black rhinos remain in the wild and conservationists are searching for solutions that could permanently protect the critically endangered species.

The red-billed oxpecker has also declined. The birds feed on ticks, including those burrowed in cattle, but for decades, farmers treated their livestock with pesticides to kill the parasites. This inadvertently transferred the poison to oxpeckers, causing them to die out in some regions in Africa. In turn, many black rhinos must navigate the landscape without their avian companions. Given the study’s findings, Plotz thinks conservationists should consider reintroducing oxpecker sentinels to rhino populations.

“The oxpeckers are clearly adding a new depth and dimension to rhino awareness levels,” says animal ecologist Jo Shaw, Africa rhino program manager at World Wildlife Fund South Africa. “This emphasizes further the complex webs between species within ecosystems and the need for conservationists to work to ensure all functions remain intact.”

However, wildlife ecologist Michael Knight, chair of the International Union for Conservation of Nature’s African Rhino Specialist Group, cautions that a lot of poaching takes place during full-moon nights when sleeping oxpeckers would be of less assistance.

Hitchhiking oxpeckers warn endangered rhinos when people are nearby

20 minutes in nature a day is your ticket to feeling better

On April 3, 2020 By A.P.In UncategorizedLeave a comment

Nature soothes our stressed-out souls. We instinctively know nature is the best prescription, but research is revealing how little time we need to set aside to reap the benefits.

In one study, published in the journal Frontiers in Psychology, researchers tried to identify the most effective “dose” of nature within the context of normal daily life. As more doctors prescribe nature experiences for stress relief and other health benefits — sometimes referred to as a “nature pill” — the study’s authors hoped to clarify the details of these treatments. More biophilia is generally better for us, but since not everyone can spend all day in deep wilderness, the study looked for a sweet spot.

“We know that spending time in nature reduces stress, but until now it was unclear how much is enough, how often to do it, or even what kind of nature experience will benefit us,” says lead author MaryCarol Hunter, an associate professor at the University of Michigan’s School for Environment and Sustainability, in a statement. “Our study shows that for the greatest payoff, in terms of efficiently lowering levels of the stress hormone cortisol, you should spend 20 to 30 minutes sitting or walking in a place that provides you with a sense of nature.”

A nature pill can be a low-cost, low-risk way to curb the negative health effects of urbanization and indoor lifestyles. To find the most efficient dosage, Hunter and her co-authors asked 36 city dwellers to have nature experiences of at least 10 minutes three times per week over eight weeks. (A nature experience was defined as “anywhere outside that, in the opinion of the participant, made them feel like they’ve interacted with nature,” Hunter explains.) Every two weeks, the researchers collected saliva samples to measure levels of the stress hormone cortisol, both before and after the participants took their nature pill.

The data showed that just a 20-minute nature experience was enough to significantly reduce cortisol levels. The effect was most efficient between 20 to 30 minutes, after which benefits continued to accrue but at a slower rate. Researchers in the United Kingdom who analyzed the routines of roughly 20,000 people came up with a similar prescription: 2 hours a week total spent in a park or woodland setting will improve your health.

Nature time doesn’t have to mean exercise, either

Those results dovetail with the findings of other studies, one of which found that spending 20 minutes in an urban park can make you happier, regardless of whether you use that time to exercise. That study was published in the International Journal of Environmental Health Research,

“Overall, we found park visitors reported an improvement in emotional well-being after the park visit,” lead author and University of Alabama at Birmingham professor Hon K. Yuen said in a statement. “However, we did not find levels of physical activity are related to improved emotional well-being. Instead, we found time spent in the park is related to improved emotional well-being.”

For this study, 94 adults visited three urban parks in Mountain Brook, Alabama, completing a questionnaire about their subjective well-being before and after their visit. An accelerometer tracked their physical activity. A visit lasting between 20 and 25 minutes demonstrated the best results, with a roughly 64 percent increase in the participants’ self-reported well-being, even if they didn’t move a great deal in the park. That last point is particularly positive, since it means most anyone can benefit from visiting a nearby park, regardless of age or physical ability.

The study’s co-author and another UAB professor, Gavin Jenkins, acknowledges the study pool was small, but its findings illustrate the importance of urban parks.

“There is increasing pressure on green space within urban settings,” Jenkins said in the statement. “Planners and developers look to replace green space with residential and commercial property. The challenge facing cities is that there is an increasing evidence about the value of city parks but we continue to see the demise of theses spaces.”

In another review published in Frontiers in Psychology, researchers at Cornell University examined the results of 14 studies that focused on the impact of nature on college students. They found that you might not even need the full 20 minutes to reap the benefits of some outdoor time. The studies showed that as little as 10–20 minutes of sitting or walking in nature can help college students feel happier and less stressed.

“It doesn’t take much time for the positive benefits to kick in,” said lead author Gen Meredith, associate director of the Master of Public Health Program and lecturer at the College of Veterinary Medicine, in a statement. “We firmly believe that every student, no matter what subject or how high their workload, has that much discretionary time each day, or at least a few times per week.”

https://www.mnn.com/health/fitness-well-being/blogs/urban-park-20-minutes-feel-better-study

Ecuadorian Cactus Absorbs Ultrasound, Enticing Bats to Flowers

On January 20, 2020 By A.P.In UncategorizedLeave a comment

by EMILY MAKOWSKI

Plants pollinated by nectar-drinking bats often have flowers that reflect ultrasonic waves, making it easier for the animals to locate flowers through echolocation. But one cactus does the opposite—it absorbs more ultrasound in the area surrounding its flowers, making them stand out against a “quieter” background, according to a preprint published on bioRxiv last month.

Espostoa frutescens is a type of column-shaped cactus found only in the Ecuadorian Andes mountains. It has small flowers on its side that open at night, attracting bats as they fly from flower to flower in search of nectar. One of its main pollinators is Geoffroy’s tailless bat (Anoura geoffroyi).

“Bats are really good pollinators,” Ralph Simon, a postdoc in Wouter Halfwerk’s lab at Vrije Universiteit Amsterdam and the lead author of the preprint, tells The Scientist. “They carry a lot of pollen in their fur, and they have a huge home range so they can transport pollen from plants that grow far apart. For plants with a patchy distribution pattern like this cactus, it’s especially beneficial to rely on bats for pollination,” he says.

For bats to find the flowers at night, they use echolocation, emitting ultrasonic calls too high for humans to hear that bounce off objects and allow the bats to form a mental map of their surroundings. Some plants have evolved techniques that take advantage of this sonar system and allow bats to better detect flowers, such as making their petals more concave, forming a more reflective surface that can bounce more echolocation back to the bat. But E. frutescens takes a different approach.

Each of E. frutescens’s flowers are surrounded by an area of wooly hairs called the cephalium. Simon and colleagues knew from past measurements that the hairs were sound-absorbent, and were interested in seeing whether this part of the cactus could be involved in helping bats find the flowers. They attached a microphone and speaker to a device resembling the shape and size of a bat head in order to mimic a bat, and played prerecorded echolocation calls to the cacti and measured how much sound was reflected back to the bat replica.

The team found that the hairy cephalium absorbed ultrasound, and that the greatest absorption occurred above 90 kHz, in the range of the frequency of Geoffroy’s tailless bat’s echolocation call. The sound that bounced back to the microphone from the cephalium area was about 14 decibels quieter than the sound that bounced off the non-hairy part of the cacti.

It’s a “totally different mechanism” than the reflection method other cacti use, says Simon. “Instead of making the flowers conspicuous, it dampens the background. The background absorbs the ultrasound, and the flowers show up in [the middle of] this absorbent fur.”

This mechanism makes sense from a communication standpoint, writes May Dixon, a graduate student studying bat behavior in Mike Ryan’s lab at the University of Texas at Austin who was not involved with the study, in an email to The Scientist. “If you are trying to send a message, you have to think not only about the message itself but also the context. For example, if you are calling someone, you should be loud enough for them to hear, sure, but you should also call from a quiet place,” she says.

“There is something wonderful about the ways that plants have found to communicate with animals through evolution,” Dixon notes. “A cactus has no sense of what it is to be a bat—it can’t see, smell, or echolocate—but here it is, sending a bat a message in a language that a bat can understand.”

The cephalium appears to have originally evolved to protect flowers from environmental stressors such as UV rays, drying out, getting too cold, or being eaten, but “during evolution, it co-opted another function, and it functions as a sound absorbing structure as well,” says Simon. The evolution of this mechanism benefits both cactus and bat. “From the bat point of view, with this mechanism, they save time. And for them, it’s important to save time, because they have to visit several hundred flowers each night to get enough energy,” he says.

The current study did not look at whether sites on the plants with the highest sound absorption in the bats’ echolocation range “indeed resulted in the highest detection and visitation rates by bats,” says Jan Komdeur, an evolutionary ecologist at University of Groningen in the Netherlands who did not participate in the research, in an email to The Scientist. In the future, researchers could investigate how often real-life bats approach hairy versus experimentally manipulated hairless flowers, he suggests.

Jorge Schondube, an ecologist at the Universidad Nacional Autónoma de México who was not involved with the study, agrees that research on real-life bats is needed. “The pattern’s very clear, but now [researchers] need to show how the mechanism is actually changing the behavior of the bats,” he says.

Still, he’s impressed by the findings so far. “Nature is very creative. And by being creative, it allows the origin of completely new and unimaginable things. It’s really surprising that something like this can happen, and the paper shows it really, really beautifully. . . . What we’re seeing here is something that has not been seen before in terms of sound.”

https://www.the-scientist.com/news-opinion/ecuadorian-cactus-absorbs-ultrasound–enticing-bats-to-flowers-66981?utm_campaign=TS_DAILY%20NEWSLETTER_2020&utm_source=hs_email&utm_medium=email&utm_content=82166272&_hsenc=p2ANqtz-9in3Tqjl731fVW0JE_k3Ht2NOEvCOnql7E5ADhmEp4j43Rrs5Q6gxTipSPvHXAs-8C6MvOvVFdBpktnFeyya1pvZPF2A&_hsmi=82166272

Bounding and Galloping crocodiles

On December 24, 2019December 23, 2019 By A.P.In UncategorizedLeave a comment

Even on land, crocodiles are no fish out of water. While these reptiles might look lazy and slow sunning on the bank, they can easily pick up speed when necessary, and a scary number can gallop or bound like a horse or a dog.

Bounding is when an animal’s forelimbs hit the ground at the same time, with the back legs pushing off soon after; meanwhile, a gallop is a four-beat sequence whereby the fore and hindlimbs take turns landing.

Freshwater crocodiles from Australia (Crocodylus johnstoni) were historically thought to be the only species capable of doing both. But that’s not actually true. Not even close.

It turns out even scientists have underestimated these creatures. Past research suggested only a handful of croc species were able to gallop, but a new study now adds five more to the mix, suggesting it’s a whole lot more common than we ever thought.

Setting up video cameras around a zoological park in Florida, veterinary scientists analysed the gaits and speeds of 42 individuals from 15 species of crocodylia, which includes true crocodiles (family Crocodylidae), alligators and caimans.

While alligators and caimans were only able to trot on land, the team noticed eight species of crocodile capable of galloping or bounding.

They claim their study is the first to properly document galloping in the Philippine crocodile (Crocodylus mindorensis), the Cuban crocodile (C. rhombifer), the American crocodile (C. acutus), the West-African slender-snouted crocodile (Mecistops cataphractus) and the dwarf crocodile (Osteolaemus tetraspis).

Judging by how common this skill appears to be, there might even be more species that can do the same. There have already been anecdotal reports of galloping in species such as the marsh crocodile (C. palustris) and the New Guinea crocodile (C. novaeguineae).

“We were really surprised at one major thing – despite the different gaits crocodiles and alligators use, they all can run about as fast,” John Hutchinson, a specialist in evolutionary biomechanics at the Royal Veterinary College (RVC), told PA.

No matter what their size, almost every species studied was able to reach nearly 18 kilometres per hour (11 mph), whether it be through trotting, galloping or bounding.

Only crocodiles, however, could use their legs asymmetrically, providing longer stride frequencies, especially among those with smaller body sizes. Why alligators cannot do this remains uncertain, but the researchers think this skill is probably ancestral and has less to do with speed than we thought.

“We suspect that bounding and galloping give small crocodiles better acceleration and manoeuvrability, especially useful for escaping from danger,” explains Hutchinson

“It seems like alligators and caiman stand their ground rather than run away with an extreme gait.”

Similar to other studies, the researchers think the crocodile’s unusual asymmetrical gait came from a long-lost ancestor that lived on the land and had longer legs.

If this is right, it could mean that the ancestors of the alligators somehow lost this ability or no longer express it.

But there’s also another possibility that is rarely acknowledged: the common ancestor of today’s 20 crocodile species may have actually evolved this asymmetrical gait as opposed to inheriting it.

Looking at related species could clear up some of the confusion – the gharial is an Asian fish-eating crocodile that lies outside the Crocodyloidea and Alligatoroidea ancestry, so if they can be shown to have asymmetrical gaits, it could shed light on how this skill appeared.

But similar to crocodiles and alligators, the gaits of the gharial’s are not well documented, so there’s clearly a lot more research that needs to be done.

“Together, our new observations of asymmetrical gaits and our broader dataset on locomotor kinematics spanning the clade Crocodylia considerably expand our knowledge of their behaviours and natural history,” the authors conclude.

“Importantly, this combined evidence strongly refutes the popular notion that only a few crocodiles use asymmetrical gaits.”

The study was published in Scientific Reports.

https://www.sciencealert.com/approach-with-caution-more-crocodile-species-than-we-thought-can-reach-a-gallop

Predators may make prey get smart and grow more brain cells

On December 11, 2019 By A.P.In UncategorizedLeave a comment

By Chelsea Whyte

Sometimes stress can be good for a fish. When there are more predators around, killifish in Trinidad grow more brain cells than those that face no predators, and they do so even into adulthood.

“I was surprised to find this because in previous studies, we found that predators inhibit the production of brain cells,” says Kent Dunlap at Trinity College in Connecticut. It seems that killifish swim their own way.

Dunlap and his colleagues examined the brains of a type of wild caught killifish (Rivulus hartii) from three streams on the Caribbean island. In each stream, they gathered about eight adult fish from a location with a high number of predators and about eight from a location with little to no predation. They only used males because previous research on these fish showed that predation affects male but not female brains.

The researchers measured the size of the males’ brains as well as the density of newly grown cells. They found that fish from both spots in each stream had brains similar in size relative to their bodies, but those that had to fight off more predators had nearly double the amount of new brain cells. Dunlap says this may mean that instead of fairly static brains that respond to predators in a timid way, the new brain cells could allow for more responsive behaviour.

To sort out whether this effect is genetic or purely a response to their environment, Dunlap and his team raised fish from each location and then dissected their brains. In the lab, even with an absence of predators, they saw that the increased brain cell growth persisted in fish descended from those that lived in high-predation areas.

“Over evolutionary time, predation has caused the populations to differ genetically, so there’s this intrinsic difference now that’s upheld,” says Dunlap. He adds that this pattern would likely show up in other animals that continue to grow brain cells into adulthood.

“We mammals and birds, once we reach sexual maturation our body and brain don’t grow very much,” he says. “But fish grow throughout their lifetime, as do many other non-birds and non-mammals.”

Journal reference: Royal Society Proceedings B, DOI: 10.1098/rspb.2019.1485

Pig-Monkey Hybrid Engineered in China

On December 8, 2019December 7, 2019 By A.P.In UncategorizedLeave a comment

This piglet had some cells from a monkey but died within a week of birth
Tang Hai

By Michael Le Page

Pig-primate chimeras have been born live for the first time but died within a week. The two piglets, created by a team in China, looked normal although a small proportion of their cells were derived from cynomolgus monkeys.

“This is the first report of full-term pig-monkey chimeras,” says Tang Hai at the State Key Laboratory of Stem Cell and Reproductive Biology in Beijing.

The ultimate aim of the work is to grow human organs in animals for transplantation. But the results show there is still a long way to go to achieve this, the team says.

Hai and his colleagues genetically modified cynomolgus monkey cells growing in culture so they produced a fluorescent protein called GFP. This enabled the researchers to track the cells and their descendents. They then derived embryonic stem cells from the modified cells and injected them into pig embryos five days after fertilisation.

More than 4000 embryos were implanted in sows. Ten piglets were born as a result, of which two were chimeras. All died within a week. In the chimeric piglets, multiple tissues – including in the heart, liver, spleen, lung and skin – partly consisted of monkey cells, but the proportion was low: between one in 1000 and one in 10,000.

It is unclear why the piglets died, says Hai, but because the non-chimeric pigs died as well, the team suspects it is to do with the IVF process rather than the chimerism. IVF doesn’t work nearly as well in pigs as it does in humans and some other animals.

The team is now trying to create healthy animals with a higher proportion of monkey cells, says Hai. If that is successful, the next step would be to try to create pigs in which one organ is composed almost entirely of primate cells.

Something like this has already been achieved in rodents. In 2010, Hiromitsu Nakauchi, now at Stanford University in California, created mice with rat pancreases by genetically modifying the mice so their own cells couldn’t develop into a pancreas.

Pig-human chimeras

In 2017, Juan Carlos Izpisua Belmonte’s team at the Salk Institute in California created pig-human chimeras, but only around one in 100,000 cells were human and, for ethical reasons, the embryos were only allowed to develop for a month. The concern is that a chimera’s brain could be partly human.

This is why Hai and his team used monkey rather than human cells. But while the proportion of monkey cells in their chimeras is higher than the proportion of human cells in Belmonte’s chimeras, it is still very low.

“Given the extremely low chimeric efficiency and the deaths of all the animals, I actually see this as fairly discouraging,” says stem cell biologist Paul Knoepfler at the University of California, Davis.

He isn’t convinced that it will ever be possible to grow organs suitable for transplantation by creating animal-human chimeras. However, it makes sense to continue researching this approach along with others such as tissue engineering, he says.

According to a July report in the Spanish newspaper El País, Belmonte’s team has now created human-monkey chimeras, in work carried out in China. The results have not yet been published.

While interspecies chimerism doesn’t occur naturally, the bodies of animals including people can consist of a mix of cells. Mothers have cells from their children growing in many of their organs, for instance, a phenomenon called microchimerism.

Journal reference: Protein & Cell, DOI: 10.1007/s13238-019-00676-8

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