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Honeybees Waggle To Communicate. But To Do It Well, They Need Dance Lessons




In a castaway test setup, groups of young honeybees figuring out how to forage on their own start waggle dancing spontaneously — but badly.

Waggling matters. A honeybee’s rump-shimmy runs and turning loops encode clues that help her colony mates fly to food she has found, sometimes kilometers away. However, five  colonies in the new test had no older sisters or half-sisters around as role models for getting the dance moves right.

Still, dances improved in some ways as the youngsters wiggled and looped day after day, reports behavioral ecologist James Nieh of the University of California, San Diego. But when waggling the clues for distance information, Apis mellifera without role models never did match the timing and coding in normal colonies where young bees practiced with older foragers before doing the main waggle themselves.

The youngsters-only colonies thus show that social learning, or the lack of it, matters for communicating by dance among honeybees, Nieh and an international team of colleagues say in the March 10 Science. Bee waggle dancing, a sort of language, turns out to be both innate and learned, like songbird or human communication.

The dance may appear simple in a diagram, but executing it on expanses of honeycomb cells gets challenging. Bees are “running forward at over one body length per second in the pitch black trying to keep the correct angle, surrounded by hundreds of bees that are crowding them,” Nieh says.

Beekeepers and biologists know that some kinds of bees can learn from others of their kind — some bumblebees even tried soccer (SN: 2/23/17). But when it comes to waggle dancing, “I think people have assumed it’s genetic,” Nieh says. That would make this fancy footwork more like the chatty but innate communications of cuttlefish color change, for instance. The lab bee-castaway experiments instead show a nonhuman example of “social learning for sophisticated communication,” Nieh says.

Testing for social learning took some elaborate beekeeping. At an apiary research center in Kunming, China, researchers put thousands of nearly grown-up honeybees (at what’s called the purple-eyed pupae stage) into incubators and then collected the brand-new winged adults when they emerged.

These youngsters went into five weirdly populated colonies of same-age worker newbies. Each colony got a queen, who would lay eggs but not leave the colony to forage. Food had to come from the young workforce, with no older, experienced foragers buzzing in and dancing the locations of flowers.

In waggle dancing, foraging bees have to master not only the moves but the obstacles of the honeycomb dance floor. A cell may be empty. “It’s just the edges to hang on to…. It would be easy to stumble,” Nieh says. Unlike commercial hives with manufactured uniform honeycomb cells, natural combs “are very irregular,” he says. “Along the edges, they get a bit crazy and rough.”

A honeybee that brings home food to her colony does a looping, waggling dance that tells her colony mates how to find the source. In the center, a bee with a green dot on her back is doing her first waggle dance as other bees crowd around. She’s already gotten to follow along with dances by other experienced foragers, so she makes fairly regular figure eights. Bees that don’t have such mentors don’t nail the dance moves as well, a new study shows. 

Dances on these treacherous surfaces encode the food’s direction in the angle a dancer waggles across the comb (measured relative to gravity). Duration of waggling bout gives a clue on how far away the bonanza is.

The five colonies of castaways were left to figure out dancing on their own, in contrast to five other colonies in the apiary with a natural mix. Early in the experiments, researchers recorded and analyzed the first dances of five bees from each hive.

Even in the mixed-age hives, the dancers didn’t get the angle perfect every time. The extremes in a set of six waggle runs might differ by a bit more than 30 degrees. The castaway hives, though, had far more trouble at first. Two of the five castaway dancers’ angles veered more than 50 degrees apart, and one poor bee strayed more than 60 degrees in six repeats.

Waggle dancing lets honeybees share news about where to find food. The honeybee marked with a purple dot that’s making irregular figure eight loops in the center did not have older, experienced foragers around to lead her in practice dances. As a result, her first dance is rough and other bees seem to be colliding with her as much as following her. A study comparing bees with and without dance mentors suggests that this sophisticated communication is a mix of innate and learned behavior.

As the castaways got more experience, they got better though. Repeating the test with the same marked bees a few weeks later near the end of their lives found them angling about as well as dancers in a normal hive.

What the castaways didn’t change much were dance features that encode distance to food. Researchers had set up the hives so that all would have the same experience of flying the distance to a feeder. Yet castaway bees persisted in dancing as if it were farther.

They gave more rump wags per waggle run (closer to five wags) than bees from mixed-age hives (more like 3.5 wags). The youngsters also took longer on each run.

Evidence like this foraging study is “indeed accumulating for the importance of learning (whether individual or social) in the complex behaviors of bees,” insect ecophysiologist Tamar Keasar of the University of Haifa in Israel says in an email. In her own work, she sees bees learning to extract food from complicated flowers. Bees aren’t, after all, just little automatons with wings.


Scientists Have Now Recorded Brain Waves From Freely Moving Octopuses





For the first time, scientists have recorded brain waves from freely moving octopuses. The data reveal some unexpected patterns, though it’s too early to know how octopus brains control the animals’ behavior, researchers report February 23 in Current Biology.

“Historically, it’s been so hard to do any recordings from octopuses, even if they’re sedated,” says neuroscientist Robyn Crook of San Francisco State University, who was not involved in the study. “Even when their arms are not moving, their whole body is very pliable,” making attaching recording equipment tricky.

Octopuses also tend to be feisty and clever. That means they don’t usually put up with the uncomfortable equipment typically used to record brain waves in animals, says neuroethologist Tamar Gutnick of the University of Naples Federico II in Italy. 

To work around these obstacles, Gutnick and colleagues adapted portable data loggers typically used on birds, and surgically inserted the devices into three octopuses. The researchers also placed recording electrodes inside areas of the octopus brain that deal with learning and memory. The team then recorded the octopuses for 12 hours while the cephalopods went about their daily lives — sleeping, swimming and self-grooming — in tanks.

Some brain wave patterns emerged across all three octopuses in the 12-hour period. For instance, some waves resembled activity in the  human hippocampus, which plays a crucial role in memory consolidation. Other brain waves were similar to those controlling sleep-wake cycles in other animals.

The researchers also recorded some brain waves that they say have never been seen before in any animal. The waves were unusually slow, cycling just two per second, or 2 hertz. They were also unusually strong, suggesting a high level of synchronization between neurons. Sometimes just one electrode picked up the weird waves; other times, they showed up on electrodes placed far apart,

Observing these patterns is exciting, but it’s too early to tell whether they’re tied to a specific behavior or type of cognition, Gutnick says. Experiments with repetitive tasks are necessary to fully understand how these brain areas are activated in octopuses during learning.

The new research is exciting in that it provides a technique for future researchers to observe brain activity in awake and naturally behaving octopuses, Crook says. It could be used to explore brain activity behind the animals’ color-changing abilities, spectacular vision, sleep patterns and adept arm control (SN: 1/29/16; SN: 3/25/21).

Octopuses are highly intelligent, so by studying the creatures “you can get ideas about what is important for intelligence,” Gutnick says. “The problems that the animals face are the same problems, but the solutions that they find are sometimes similar and sometimes different and all of these comparisons teach us something.”

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Static Electricity Helps Parasitic Nematodes Glom Onto Victims





LAS VEGAS — Some species of parasitic roundworms can catapult themselves high into the air to latch onto fruit flies and other insects. Experiments now reveal that leaping Steinernema carpocapsae nematodes take advantage of a secret weapon that makes them particularly effective in their pursuit of victims: static electricity.

Flying insects build up electric charge as they move through the air (SN: 10/31/22). It’s the same effect that causes electricity to collect on droplets of mist in clouds, and ultimately leads to lightning.

Individual insects can accumulate charges of 100 volts or so, biomechanics researcher Víctor Ortega Jiménez of the University of Maine in Orono reported March 6 at the American Physical Society meeting. When nematodes leap, the charge on a passing insect attracts the parasites like lint to a staticky sweater.

An insect in the top middle of the frame with a rainbow of colors surrounding it. The arrows show the direction the nematodes move; colors indicate relative speed with blue for slower and red for faster. 
As an insect moves, it builds up charges that create surrounding electric fields. Those charges create static electricity that pulls parasitic nematodes toward the insect, new research reveals. The arrows show the direction the nematodes move; colors indicate relative speed with blue for slower and red for faster.Víctor M. Ortega Jiménez

To test the effect of electric charge, Ortega Jiménez and colleagues mounted dead fruit flies on wires and placed them near a surface covered in nematodes. With no charge on a fly, only nematodes that happened to jump in the direction of the insect landed on target, as expected. When researchers applied an electric charge to a suspended fruit fly, even nematodes that initially headed in the wrong direction were caught up in the electric field and pulled onto the fly.

Ortega Jiménez has also studied electric force effects on spider webs. When charged insects neared a web, “the silk is attracted directly to the insects,” he says. That made him wonder whether leaping nematodes rely on those forces as well.

Researchers have long considered the effect of fluids and air flow on insects and other tiny creatures. But only recently have they added electricity to the mix, Ortega Jiménez says. “We need to know how animals actually are dealing with these forces at this scale.”

Some teeny-tiny parasitic roundworms called nematodes have an unerring ability to leap high into the air to land on fruit flies and other living prey. It turns out that the prey unwittingly give the nematodes a hand, new research shows. By simply moving, a fly builds up an electric charge. Like static electric cling, that charge can pull a nematode in. In this experiment, researchers applied an electric charge to a pinned-in-place fly. A speck of a nematode (left) cartwheeled into the air and then headed straight for the fly.

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This Fish Could Expand What We Know About One Odd Deep-Sea Ecosystem





Off the Pacific coast of Costa Rica sits a deep-sea chimera of an ecosystem. Jacó Scar is a methane seep, where the gas escapes from sediment into the seawater, but the seep isn’t cold like the others found before it. Instead, geochemical activity gives the Scar lukewarm water that enables organisms from both traditionally colder seeps and scalding hot hydrothermal vents to call it home.

One resident of the Scar is a newly identified species of small, purplish fish called an eelpout, described for the first time on January 19 in Zootaxa. This fish is the first vertebrate species found at the Scar and could help scientists understand how the unique ecosystem developed. 

Jacó Scar was discovered during exploration of a known field of methane seeps off the Costa Rican coast and named for the nearby town of Jacó. It is “a really diverse place” with many different organisms living in various microhabitats, says Lisa Levin, a marine ecologist at Scripps Institution of Oceanography in La Jolla, Calif.

Levin was on one of the first expeditions to the Scar but wasn’t involved in the new study. She recalls the team finding and collecting one of the fish during this early excursion, but the researchers didn’t recognize it as a new species.

Several more specimens were snagged during later submersible dives. Charlotte Seid, an invertebrate biologist at Scripps who is working on a checklist of organisms found at the Costa Rican seeps, brought the fishy finds to ichthyologist Ben Frable, also of Scripps, for formal identification.

Frable says he knew the fish was an eelpout. They look exactly as one would expect based on their name: like frowning eels, though they aren’t true eels. But he was having trouble determining what type. Eelpouts are a diverse family of fish comprised of nearly 300 species that can be found all over the world at various ocean depths.

Because the physical differences between species can be subtle, they are “kind of a tricky group” to identify, Frable says. “I just was not really getting anywhere.” So the team turned to eelpout expert Peter Rask Møller of the Natural History Museum of Denmark in Copenhagen, sending him X-rays, pictures and eventually one of the fish specimens.

Møller narrowed the enigmatic eelpout to the genus Pyrolycus, meaning “fire wolf.” Turns out, the tool, called a dichotomous key, that Frable had been using to identify the specimens was outdated, made before Pyrolycus was described in 2002. “I did not know that genus existed,” Frable says.

Because the other two known Pyrolycus species live far away in the western Pacific and have different physical features, the team dubbed the mystery fish P. jaco — a new species.

The first eelpouts most likely evolved in cold waters, Frable says, but many have since made their home in the scalding waters of hydrothermal vents. Of the 24 known fish species that live only at hydrothermal vents, “13 of them are eelpouts,” Frable says.

A Pyrolycus jaco specimen is shown freshly collected (top), preserved (middle) and in X-rays superimposed over the fresh image (bottom), all on a black background.
A Pyrolycus jaco specimen is shown freshly collected (top), preserved (middle) and in X-rays superimposed over the fresh image (bottom).B. Frable and C. Seid/Scripps Institution of Oceanography

The new finding raises questions about how the known Pyrolycus species came to live so far apart. It may have to do with the fact that methane seeps are more common than previously thought on the ocean floor, and if some are lukewarm like Jacó Scar, the new species could have used them as refuges while moving east.

And by comparing P. jaco to its vent-living relatives, researchers may be able to figure out how it adapted to live in the tepid waters of the Scar — which may provide clues to how other species living there did too.

The eelpout is part of a medley of other species that form Jacó Scar’s composite ecosystem, along with, for example, clams typically found at cold seeps and bacteria found at hydrothermal vents. Jacó Scar is a “mixing bowl” of species found in other parts of the world, Seid says. Figuring out how this eclectic bunch interacts “is part of the fun.”

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