Posts Tagged ‘Nature’

The purpose and evolutionary origins of sleep are among the biggest mysteries in neuroscience. Every complex animal, from the humblest fruit fly to the largest blue whale, sleeps — yet scientists can’t explain why any organism would leave itself vulnerable to predators, and unable to eat or mate, for a large portion of the day. Now, researchers have demonstrated for the first time that even an organism without a brain — a kind of jellyfish — shows sleep-like behaviour, suggesting that the origins of sleep are more primitive than thought.

Researchers observed that the rate at which Cassiopea jellyfish pulsed their bell decreased by one-third at night, and the animals were much slower to respond to external stimuli such as food or movement during that time. When deprived of their night-time rest, the jellies were less active the next day.

“Everyone we talk to has an opinion about whether or not jellyfish sleep. It really forces them to grapple with the question of what sleep is,” says Ravi Nath, the paper’s first author and a molecular geneticist at the California Institute of Technology (Caltech) in Pasadena. The study was published in Current Biology.

“This work provides compelling evidence for how early in evolution a sleep-like state evolved,” says Dion Dickman, a neuroscientist at the University of Southern California in Los Angeles.

Mindless sleep
Nath is studying sleep in the worm Caenorhabditis elegans, but whenever he presented his work at research conferences, other scientists scoffed at the idea that such a simple animal could sleep. The question got Nath thinking: how minimal can an animal’s nervous system get before the creature lacks the ability to sleep? Nath’s obsession soon infected his friends and fellow Caltech PhD students Michael Abrams and Claire Bedbrook. Abrams works on jellyfish, and he suggested that one of these creatures would be a suitable model organism, because jellies have neurons but no central nervous system. Instead, their neurons connect in a decentralized neural net.

Cassiopea jellyfish, in particular, caught the trio’s attention. Nicknamed the upside-down jellyfish because of its habit of sitting on the sea floor on its bell, with its tentacles waving upwards, Cassiopea rarely moves on its own. This made it easier for the researchers to design an automated system that used video to track the activity of the pulsing bell. To provide evidence of sleep-like behaviour in Cassiopea (or any other organism), the researchers needed to show a rapidly reversible period of decreased activity, or quiescence, with decreased responsiveness to stimuli. The behaviour also had to be driven by a need to sleep that increased the longer the jellyfish was awake, so that a day of reduced sleep would be followed by increased rest.

Other researchers had already documented a nightly drop in activity in other species of jellyfish, but no jellyfish had been known to display the other aspects of sleep behaviour. In a 35-litre tank, Nath, Abrams and Bedbrook tracked the bell pulses of Cassiopea over six days and nights and found that the rate, which was an average of one pulse per second by day, dropped by almost one-third at night. They also documented night-time pulse-free periods of 10–15 seconds, which didn’t occur during the day.

Restless night
Without an established jellyfish alarm clock, the scientists used a snack of brine shrimp and oyster roe to try to rouse the snoozing Cassiopea. When they dropped food in the tank at night, Cassiopea responded to its treat by returning to a daytime pattern of activity. The team used the jellyfish’s preference for sitting on solid surfaces to test whether quiescent Cassiopea had a delayed response to external stimuli. They slowly lifted the jellyfish off the bottom of the tank using a screen, then pulled it out from under the animal, leaving the jelly floating in the water. It took longer for the creature to begin pulsing and to reorient itself when this happened at night than it did during the day. If the experiment was immediately repeated at night, the jellyfish responded as if it were daytime. Lastly, when the team forced Cassiopea to pull an all-nighter by keeping it awake with repeated pulses of water, they found a 17% drop in activity the following day.

“This work shows that sleep is much older than we thought. The simplicity of these organisms is a door opener to understand why sleep evolved and what it does,” says Thomas Bosch, an evolutionary biologist at Kiel University in Germany. “Sleep can be traced back to these little metazoans — how much further does it go?” he asks.

That’s what Nath, Abrams and Bedbrook want to find out. Amid the chaos of finishing their PhD theses, they have begun searching for ancient genes that might control sleep, in the hope that this might provide hints as to why sleep originally evolved.

https://www.nature.com/news/jellyfish-caught-snoozing-give-clues-to-origin-of-sleep-1.22654

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By Sean Quinton

This is a tale of a rabbit, a fox and an eagle — but it’s no bedtime story.

An incredible display of nature unfolded Saturday on San Juan Island as a young fox quickly learned a valuable lesson about the pecking order in the Northwest wilderness.

A fox kit pranced along the prairie of San Juan Island National Historical Park with a rabbit clenched in its jaws, apparently pleased with its catch. Then the predator pauses abruptly, looks up and sees a bald eagle coming its way. The predator becomes the prey.

The fox tumbles and spins, and the eagle swoops to take hold of the rabbit. Both the rabbit and the fox are lifted into the air. The eagle flaps its wings. The fox doesn’t give up right away, flailing its young legs.

But the bird is too much for the red fox, which lets go of the rabbit and falls twirling back to the ground. The bird of prey won the battle.

The eight-second spectacle was captured on video.

Zachary Hartje was shooting photos when he anticipated what was about to happen in the prairie. He switched his camera to video mode.

“I was totally shocked,” he said. “No one I had ever talked to had ever seen anything like that.”

Hartje recently graduated from Gonzaga University and goes to the San Juan Islands several times a year to film and photograph the foxes there.

“It was a baby fox, so it might’ve been its first kill,” he said. “The fox just ran away into the den after. It looked pretty scared.”

Another photographer, Kevin Ebi, was also there to watch the fox kits.

“When I heard the bald eagle calling, I knew exactly what was going to happen,” Ebi said, who posted his photos to his blog, LivingWilderness.com. “I knew it wanted that rabbit.”

“After I saw the eagle finally drop the fox … I thought, ‘This is one of the most incredible things I’ve ever seen.’ “

Ebi said he has photographed eagles for years. He even published a book called “Year of the Eagle,” which chronicles the life of the Pacific Northwest birds. Even for him, the event was unprecedented.

Ebi said eagles don’t like to expend more calories than they need to get food, so when they see some other animal that’s already done the work of hunting, they might try to swoop in to steal a meal. The behavior is called kleptoparasitism.

Saturday’s confrontation was on another level. “This is the most difficult attempt I’ve ever seen and it’s extremely uncommon,” Ebi said.

The fox appeared to escape without injury, but next time it might think twice before taking its prey across the prairie.

Large boulders 2 metres across and weighing 10 tonnes could soon begin blasting out from Kilauea, the erupting volcano on Hawaii’s Big Island. But the biggest imminent threat to residents could arise if the volcano starts spewing ash to heights of 6000 metres or more.

The conditions are similar to those when Kilauea last erupted in 1924, which showered the island in ash for several months. “That’s what I would guess will happen next,” said Don Swanson of the Hawaiian Volcano Observatory, in a press conference video issued on 9 May.

Kilauea has been unusually active since late April. On 30 April, the floor of the lava lake at the volcano’s summit collapsed.

The lava has been draining ever since. By 9 May, and following a 6.9-magnitude earthquake on 3 May, it had already plunged almost 300 metres into the vertical shaft below. The lava is now below the level of water-saturated rock at 600 metres above sea level. “Since the earthquake, the lava lake has dropped in a very steady manner, at 2.2 metres per hour,” said Swanson.

Steam explosions

Because the lava has sunk so low, water is now draining into the empty shaft that it previously occupied. The walls of the crater are red hot, so the water is instantly turning to steam, which is now bellowing in white clouds from the volcano summit.

What happens next is difficult to predict, said Swanson. But there could be explosions. If large rocks fall from the unstable walls of the shaft, they could block it, in which case pressure from steam will build up underneath and cause an explosion.

Once the “plug” is blown out, the steam can escape again unimpeded, until the plug is restored by rock falls.

The result would be a series of explosions followed by hiatuses. That’s what happened in 1924: there were 60 explosions over the course of four months or so.

Boulders and ash

Any explosion can produce a variety of “ejecta”, said Swanson. “You can get rocks ejected like cannonballs, weighing up to 10 tonnes and 2 [metres] in diameter,” he said.

The good news is that these boulders should fall within about a kilometre of the summit. This area is deserted. Smaller rocks the size of softballs could impact a bit further away, albeit still not far enough to reach people’s homes. But tinier fragments a fraction of an inch wide could reach peopled areas. “They would sting, but not be lethal,” says Swanson.

The most important hazard is fine ash, which can block thoroughfares and accumulate on buildings. In 1924, ash landed on railway tracks and made them too slippery for trains to run on safely.

“It’s a nuisance, especially if it goes on for several weeks,” said Tina Neal of the Hawaiian Volcano Observatory at the press conference. “I’ve been in many ash falls myself, and the most difficult bit is keeping it out of your eyes.”

Meanwhile, lava fountains and steam continue to spew copiously from cracks on the island, reaching heights of 30 metres. By Monday, there were 19 fissures in total. So far, more than 30 properties have been destroyed by lava, and 2000 residents remain evacuated.

https://www.newscientist.com/article/2168913-hawaiis-erupting-volcano-may-blast-out-10-tonne-cannonballs/

by MICHAEL D’ESTRIES

Much to the chagrin of everyone who loves the great outdoors, a new species of exotic tick has officially set up residence in the United States.

The New Jersey Department of Agriculture announced last week that the longhorned tick, a species native to China, Japan and Australia has successfully survived the New Jersey winter and may be spreading throughout the state.

The tick was first discovered in the U.S. last August after a N.J. farmer walked into a county health office covered in ticks. She reported that she had been shearing the single sheep on her property when she noticed multitudes of the four-legged blood suckers crawling up her arms. A closer inspection by health officials revealed something even more frightening: nearly 1,000 ticks moving throughout her clothing.

“What she didn’t know was her entire clothing, pants and everything, they were covered in ticks,” Tadhgh Rainey, division manager of Hunterdon County Division of Health Services, told NPR.

More unusual than this sight, however, was that officials couldn’t identify the species of tick clinging to her clothes. A team of experts later determined it to be Haemaphysalis longicornis, never before seen in the U.S., and plaguing livestock that had never ventured outside the country.

A grim discovery

A description of the team’s visit to the tick-plagued farm sounds like something straight out of a horror movie.

“Investigation of the Hunterdon property in early October revealed a large number of ticks both on the sheep and throughout the paddock,” the scientists shared in a new study published in the Journal of Medical Entomology. “The ticks in the paddock were so numerous that they crawled on investigators’ pants soon after setting foot inside. The sheep was supporting hundreds of ticks, including all three active life stages (larva, nymph, adult). Although ticks were concentrated on the sheep’s ears and face, engorged ticks of all stages were readily found all over its body, including areas beneath the animal’s thick coat.”

Following a chemical treatment in September, the sheep was later declared tick-free. Visits by officials in late November found no ticks in either the paddocks or the surrounding grounds. While scientists were hopeful that the state’s cold winter temperatures might kill off any remaining populations, the longhorned tick has one evolutionary advantage that gave them pause.

“This tick overwinters in the ground,” Rainey told NJ.com. “No tick does that.”

Sure enough, when entomologists visited the site again this spring, they were disappointed to discover that the longhorned tick had successfully overwintered. They added that, based on this evidence, the new species has quite possibly “become established in the state.”

Divide and conquer

Besides its ability to burrow underground to avoid death from freezing temperatures, the longhorned also has some other characteristics that put a frightening spin on this discovery. For one thing, the tick reproduces asexually, rapidly increasing in population by cloning itself and laying thousands of eggs. The nymphs and adults also tend to “swarm” their prey, with recorded observations of hundreds of ticks hanging from their hosts like “bunches of grapes.”

“Only one tick is needed to start a population, and they can grow to high numbers quickly,” Andrea M. Egizi, Ph.D., research scientist at the Tick-Borne Disease Laboratory at Rutgers University and senior author on the report, told Entomology Today. “They are not limited by the need to find mates, which can be difficult in a small population.”

While the longhorned ticks tested at the New Jersey sheep farm came back negative for known tick-borne disease, such as Lyme disease or borreliosis, it may be only a matter of time before they become carriers. The tick is already a known transmitter of diseases in its native ranges.

If there’s any good news to come out of this discovery, it’s that the ticks apparently don’t have a taste for human, preferring instead to swarm livestock and wildlife. Unfortunately, this also makes it easier for them to spread. In late April, federal and state wildlife officials combing the area around the farm where the infestation was first discovered found a longhorned tick on a white-tailed deer, a foreboding sign for early containment efforts.

A call for vigilance

In an effort to track the extent of the tick’s spread, N.J. Department of Agriculture officials are asking people to report infestations of unusual ticks on pets or livestock. Figuring out whether or not they’re exotic or native species may be another challenge altogether.

“Like deer ticks, the nymphs of the longhorned tick are very small (resembling tiny spiders) and can easily go unnoticed on animals and people,” they said in a statement.

The group plans to continue surveillance of potentially impacted species throughout the rest of the year.

https://www.mnn.com/health/fitness-well-being/blogs/self-cloning-longhorn-tick-new-jersey

By Mindy Weisberger

Treetop-dwelling ants from Southeast Asia have an explosive defensive move: The insects take down their foes by blowing themselves up. If that sounds gut-wrenching to you, just imagine what it feels like to the ant.

Commonly known as “exploding ants,” workers in this group respond to threats by deliberately (and fatally) rupturing their body walls, spattering rivals with toxic fluid.

Exploding ants are typically lumped together into a species group called Colobopsis cylindrical, but researchers recently determined that there are at least 15 species of these self-sacrificing insects — including one previously unknown species in Borneo, which they described in a new study.

Many animals engage in chemical warfare, stewing toxic brews in their own bodies to subdue prey or scare off enemies. Venomous creatures — which include snakes, spiders, insects, fish, cephalopods, amphibians, reptiles and even some types of mammals — deliver their toxins with stings, stabs or bites.

But others, such as skunks, venom-squirting scorpions and bombardier beetles, opt to spray their chemicals. In fact, bombardier beetles can emit their heated, poisonous blasts even after they’ve been swallowed, with unfortunate results for their predator’s digestion (and a sticky escape for the beetle).

However, defensively rupturing one’s own body — a process called autothysis, from the Greek words for “self” and “sacrifice” — is somewhat more unusual, and is known only in ants and termites, the scientists reported.

Tick, tick, boom!
The new ant species — Colobopsis explodens — was formerly called “yellow goo,” after the brightly colored gunk produced by its exploding worker ants. Their colonies can contain thousands of individuals, inhabiting the leafy canopies of trees that stand as tall as 197 feet (60 meters), and covering an area of at least 26,900 square feet (2,500 square meters), the study authors reported.

The researchers decided to make C. explodens a model species — one that scientists look at to draw conclusions about a larger group; in this case, exploding ants. They noted that C. explodens ants were “particularly prone to self-sacrifice” in the presence of threats — which included intruding researchers.

To blow themselves up, the reddish-brown minor workers — all sterile females — contracted a part of their abdomens called the gaster. They clenched it so tightly that it ruptured, spewing a yellow secretion that was manufactured in the ants’ jaw glands and had “a distinctive spice-like odor,” according to the study.

And suicidal explosions aren’t the only weird adaptation in C. explodens. Major workers — the bigger “soldier” ants that are also sterile females — have enlarged heads with raised shield-like sections that are circular and flattened at the top. The oddly shaped heads create a perfect plug that the ants use to temporarily block openings into their nests, the scientists wrote.

The findings were published online today (April 19) in the journal ZooKeys.

Original article on Live Science.

https://www.livescience.com/62354-exploding-ants-new-species.html?utm_source=notification

By MELISSA LOCKER

“Zombie-like” raccoons have taken over an Ohio town. This isn’t the inevitable re-boot of Night of the Living Dead, though, or another Walking Dead spin-off. Instead, it’s an eery invasion that has authorities looking for answers.

Police in Youngstown, Ohio, have responded to over a dozen calls from concerned humans who have spotted raccoons behaving very strangely, according to local news outlet WKBN. The raccoons were seen popping up onto their hind legs, baring their teeth, and then falling over in a comatose state. The animals weren’t easy to scare off, either, and seemed to have lost their natural fear of humans. If that wasn’t odd enough, the majority of the sightings and calls happened in the daytime even though raccoons are nocturnal.

Police received calls about 14 raccoons over the past three weeks, with some of the residents making the zombie comparison. The Ohio Department of Natural Resources said it doesn’t sound like rabies, but rather a disease called distemper. If this diagnosis is correct, distemper is not transmissible to humans, but can be spread to dogs who come in contact with zombie raccoons.

According to the American Veterinary Medical Association, distemper “attacks the respiratory, gastrointestinal and nervous systems” of infected animals and symptoms include, “head tilt, muscle twitches … seizures, and partial or complete paralysis.” Unfortunately, the affected raccoons have to be captured and put down to prevent the disease from spreading further.

http://time.com/5229420/zombie-raccoons-ohio-police-reports/

BY BRUCE BOWER

People have evolved to sleep much less than chimps, baboons or any other primate studied so far.

A large comparison of primate sleep patterns finds that most species get somewhere between nine and 15 hours of shut-eye daily, while humans average just seven. An analysis of several lifestyle and biological factors, however, predicts people should get 9.55 hours, researchers reported recently in the American Journal of Physical Anthropology. Most other primates in the study typically sleep as much as the scientists’ statistical models predict they should.

Two long-standing features of human life have contributed to unusually short sleep times, argue evolutionary anthropologists Charles Nunn of Duke University and David Samson of the University of Toronto Mississauga. First, when humans’ ancestors descended from the trees to sleep on the ground, individuals probably had to spend more time awake to guard against predator attacks. Second, humans have faced intense pressure to learn and teach new skills and to make social connections at the expense of sleep.

As sleep declined, rapid-eye movement, or REM — sleep linked to learning and memory (SN: 6/11/16, p. 15) — came to play an outsize role in human slumber, the researchers propose. Non-REM sleep accounts for an unexpectedly small share of human sleep, although it may also aid memory (SN: 7/12/14, p. 8), the scientists contend.

“It’s pretty surprising that non-REM sleep time is so low in humans, but something had to give as we slept less,” Nunn says.

Humans may sleep for a surprisingly short time, but Nunn and Samson’s sample of 30 species is too small to reach any firm conclusions, says evolutionary biologist Isabella Capellini of the University of Hull in England. Estimated numbers of primate species often reach 300 or more.

If the findings hold up, Capellini suspects that sleeping for the most part in one major bout per day, rather than in several episodes of varying durations as some primates do, substantially lessened human sleep time.

Nunn and Samson used two statistical models to calculate expected daily amounts of sleep for each species. For 20 of those species, enough data existed to estimate expected amounts of REM and non-REM sleep.

Estimates of all sleep times relied on databases of previous primate sleep findings, largely involving captive animals wearing electrodes that measure brain activity during slumber. To generate predicted sleep values for each primate, the researchers consulted earlier studies of links between sleep patterns and various aspects of primate biology, behavior and environments. For instance, nocturnal animals tend to sleep more than those awake during the day. Species traveling in small groups or inhabiting open habitats along with predators tend to sleep less.

Based on such factors, the researchers predicted humans should sleep an average of 9.55 hours each day. People today sleep an average of seven hours daily, and even less in some small-scale groups (SN: 2/18/17, p. 13). The 36 percent shortfall between predicted and actual sleep is far greater than for any other primate in the study.

Nunn and Samson estimated that people now spend an average of 1.56 hours of snooze time in REM, about as much as the models predict should be spent in that sleep phase. An apparent rise in the proportion of human sleep devoted to REM resulted mainly from a hefty decline in non-REM sleep, the scientists say. By their calculations, people should spend an average of 8.42 hours in non-REM sleep daily, whereas the actual figure reaches only 5.41 hours.

One other primate, South America’s common marmoset (Callithrix jacchus), sleeps less than predicted. Common marmosets sleep an average of 9.5 hours and also exhibit less non-REM sleep than expected. One species sleeps more than predicted: South America’s nocturnal three-striped night monkey (Aotus trivirgatus) catches nearly 17 hours of shut-eye every day. Why these species’ sleep patterns don’t match up with expectations is unclear, Nunn says. Neither monkey departs from predicted sleep patterns to the extent that humans do.

Citations
C.L. Nunn and D.R. Samson. Sleep in a comparative context: Investigating how human sleep differs from sleep in other primates. American Journal of Physical Anthropology. Published online February 14, 2018. doi:10.1002/ajpa.23427.

https://www.sciencenews.org/article/humans-primates-sleep-evolution