Starling flocks, schools of fish, and clouds of insects all agree.
- Scientists discover that active particles take a pass on Newton's Second Law.
- Active particles exist in a "swirlonic" state of matter.
- Swirlonic behavior explains some of the more dazzling natural phenomena such as starling swarms and shape-shifting schools of fish.
It's likely you've seen some of the fascinating videos of starling murmurations, great swarms of birds mysteriously flying as if with a single mind. These gigantic shapes swoop and swirl, shapeshifting their way through the skies while maintaining miraculous integrity. Maybe you've seen schools of fish shifting together into new shapes in likewise dazzling displays of synchrony.
How do these things happen? Consider them super-sized examples of a newly described state of matter that scientists at the University of Leicester in the U.K. are calling "swirlons." And swirlons are something new: They stand in some ways outside Newtonian law.
Swirlons are described in a paper recently published in Scientific Reports.
Credit: Wikimedia Commons/Big Think
According to Newton's Second Law, the acceleration of an object depends on both the force acting upon it and the object's mass. Its acceleration increases in accordance with the force being exerted, and as its mass increases, the object's acceleration decreases. These things don't happen with swirlons.
It appears that the Second Law relates only to passive, non-living objects at small and large scales. Swirlons, however, are comprised of active, living matter that moves courtesy of its own internal force. In this context, individual starlings are analogous to self-propelled particles within the larger swirlonic object, their flock.
Spotting swirlonic motion
Credit: Johnny Chen/Unsplash
The scientists at Leicester, led by mathematician Nikolai Brilliantov, came upon swirlonic matter as they developed computer models of self-propelled particles similar to simple bacteria or nanoparticles. They were interested in better understanding the movement of human crowds evacuating a crowded space, and these particles served as human stand-ins.
The word "swirlonic" comes from the circular direction in which the scientists witnessed their particles milling about in clusters that operated together as larger quasi-particles.
"We were completely baffled," says Brilliantov, "to witness how these quasi-particles swirl within active matter, behaving like individual super-particles with surprising properties including not moving with acceleration when force is applied, and coalescing upon collision to form swirlons of a larger mass."
Brilliantov tells Live Science, "[They] just move with a constant velocity, which is absolutely surprising."
It's not the first time such behavior has been seen, but the first time it's been identified as a distinct state of matter. Says Brilliantov, "These patterns have previously been observed for animals at different evolution stages, ranging from plant-animal worms and insects to fish, but rather as singular structures, not as a phase which borders other phases, resembling gaseous and liquid phases of 'normal' matter."
The researchers also saw that swirlonic particles operate on a sort of "one for all, all for one" basis. With passive particles such as water, different individual particles can exist in different states: some may evaporate into gas as others remain as liquid. The models of active particles, on the other hand, stuck together in the same state as either a liquid, solid, or gas.
Moving forward, and back, or up, or down together
Brilliantov and his colleagues hope to explore swirlons further, moving beyond their simulation into real-world investigations and experiments.
The researchers are also developing more sophisticated models that mimic the behavior of swirlonic animals such as starlings, fish, and insects. In these models, the active particles will have information-processing capabilities that allow them to make movement decisions as living creatures presumably do. They hope these models will reveal some of the secrets behind flocking, schooling, and swarming.
Another future possibility is creating man-made active particles that can self-assemble. Other Leicester experts agree that this is reason alone to continue researching swirlons.
In any event, says study co-author Ivan Tyukin, "It is always exciting to consider deepening our understanding of novel phenomena and their guiding physical principles. What we know to date is so much less than what there is to know. The phenomenon of the 'swirlon' is part of the tip of the iceberg of hidden knowledge. It leaves us with the eternal question: 'what else don't we know'?"
Exceptionally high-quality videos allow scientists to formally introduce a remarkable new comb jelly.
- Gorgeous simplicity characterizes the comb jelly recently discovered by National Oceanic and Atmospheric Administration Fisheries.
- The small denizen of the deep was spotted three times beneath the waters off Puerto Rico.
- Though it's unusual to formally identify an animal strictly based on video observations, the quality of NOAA's video made it possible in a case where there's no better alternative.
Usually, when scientists announce the discovery of a previously unknown animal, they have a specimen of the new arrival in hand. That's not the case, though, with Duobrachium sparksae, an amazing and beautiful ctenophore encountered 3,910 meters beneath the ocean surface about 40 kilometers off the coast of Puerto Rico. No one has met Duobrachium sparksae in person — we know of its existence only through several high-definition videos. ("Ctenophore" is pronounced teen-a-for, by the way.)
Says NOAA Fisheries' Marine Biologist Allen Collins in a NOAA press release, "It's unique because we were able to describe a new species based entirely on high-definition video."
It's also unique because it's such an exquisitely elegant organism.
Meet cute beneath the waves
The first encounter humanity had with the jelly occurred on April 10, 2015, when Deep Discoverer (a remotely operated vehicle or ROV) came across the gelatinous wonder. Fortunately, the ROV sports cameras that were sufficiently high-definition to clearly capture Duobrachium sparksae's fine details.
The animal was first noticed in a video feed by Mike Ford of the shoreside science team working in NOAA's Exploration Command Center far away, outside of Washington, D.C. The ROV was working the Arecibo amphitheater canyon. What Ford saw was, in his words, "a beautiful and unique organism."
Deep Discoverer's cameras produce externally high-resolution images, and are capable of measuring objects as small as a millimeter.The comb jelly's body is about 6 centimeters in size, and its tentacles are about 30 cm long.
While video-based animal identification can be controversial, there was little choice in this case. "We didn't have sample collection capabilities on the ROV at the time," says Collins. "Even if we had the equipment, there would have been very little time to process the animal because gelatinous animals don't preserve very well; ctenophores are even worse than jellyfish in this regard."
Credit: Nicholas Bezio/NOAA Office of Ocean Exploration and Research
Describing Duobrachium sparksae
All told, three individuals were observed by the scientists in three separate encounters with the ROV. The image at the top of this article is from the second encounter. The fact that three separate examples were easily spotted leaves scientists hopeful that the creature is not a rarity in the seas.
Ford describes what they saw:
"The ctenophore has long tentacles, and we observed some interesting movement. It moved like a hot air balloon attached to the seafloor on two lines, maintaining a specific altitude above the seafloor. Whether it's attached to the seabed, we're not sure. We did not observe direct attachment during the dive, but it seems like the organism touches the seafloor."
The role that Duobrachium sparksae plays in its ecosystem is not yet understood.
Finding a place in the family
The manner in which light refracted prismatically off the jelly's cilia combs immediately placed it in the ctenophore family as a start.
Collins explains, "We don't have the same microscopes as we would in a lab, but the video can give us enough information to understand the morphology in detail, such as the location of their reproductive parts and other aspects."
"We went," says Ford, "through the historical knowledge of ctenophores and it seemed clear this was a new species and genus as well. We then worked to place it in the tree of life properly."
The videos—the only "specimens" there are of Duobrachium sparksae—are now publicly accessible as part of the Smithsonian National Museum of Natural History Collection.
These tiny fish are helping scientists understand how the human brain processes sound.
- Fragile X syndrome is a genetic disorder caused by changes in a gene that scientists call the "fragile X mental retardation 1 (FMR1)" gene. People who have FXS or autism often struggle with sensitivity to sound.
- According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain.
- Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information.
Associate professor Ethan Scott and Dr. Lena Constantin recently carried out a study using zebrafish that carry the same genetic mutations as humans with "Fragile X" syndrome and autism. During their research, they discovered the neural networks and pathways that produce hypersensitivities to sound in both zebrafish and humans.
What is Fragile X syndrome?
Fragile X syndrome (commonly referred to as FXS) is a genetic disorder caused by changes in a gene that scientists call the "fragile X mental retardation 1 (FMR1)" gene. This gene typically makes a protein called fragile X mental retardation protein (FMRP) that's needed for typical brain development. The brains of people with FXS do not make this protein, and if it is there, it's abnormal.
What is autism?
Autism spectrum disorder (ASD) is a developmental disability that can cause significant social, communication, and behavioral challenges. People with ASD may communicate, interact, behave, and learn in different ways than most other people. A current diagnosis of ASD now includes several conditions that were previously diagnosed separately such as autistic disorder, pervasive developmental disorder, and Asperger syndrome.
By disrupting a specific gene in Zebrafish, we're able to better understand the same disruption of that gene in humans with FXS or autism.
Credit: slowmotiongli on Adobe Stock
"Loud noises often cause sensory overload and anxiety in people with autism and Fragile X syndrome -- sensitivity to sound is common to both conditions," Dr. Constantin explained to Science Daily.
How do zebrafish relate to humans with autism?
According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain.
The thalamus, according to Dr. Constantin, works as a control center, relaying sensory information from around the body to different parts of the brain. The hindbrain then coordinates different behavioral responses. Using the different sound tests, the team was able to study the whole brain of the zebrafish larvae under microscopes and see the activity of each brain cell individually.
According to Dr. Constantin, the research team recorded the brain activity of zebrafish larvae while showing them movies or exposing them to bursts of sound. The movies stimulated movement, a reaction to the visual stimuli that was the same for fish with the Fragile X mutation and those without. However, when the fish were given a burst of white noise, there was a dramatic difference in the brain activity of the fish with the Fragile X mutation.
After seeing how the noise radically affected the fish brain, the team designed a range of 12 different volumes of sound and found the Fragile X model fish could hear much quieter volumes than the control fish.
"The fish with Fragile X mutations had more connections between different regions of their brain and their responses to the sounds were more plentiful in the hindbrain and thalamus," said Dr. Constantin.
Essentially, the fish with Fragile X mutation had more connections between the regions of their brain and so their responses to the sounds were more notable.
Understanding how this gene disruption works in zebrafish will give us a better understanding of sound hypersensitivity in humans with FXS or autism.
"How our neural pathways develop and respond to the stimulation of our senses gives us insights into which parts of the brain are used and how sensory information is processed," Dr. Constantin said.
Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information.
"We hope that by discovering fundamental information about how the brain processes sound, we will gain further insights into the sensory challenges faced by people with Fragile X syndrome and autism."
One of the world's most isolated island groups has just been made one of the world's largest ocean reserves.
- The small island group of Tristan da Cunha has created one of the world's largest ocean sanctuaries.
- Neither fishing nor extractive activities will be allowed in the area, which is three times the size of the United Kingdom.
- Animals protected by this zone include penguins, sharks, and many seabirds.
Tristan da where now?
Tristan da Cunha is a British Overseas Territory consisting of an archipelago in the south Atlantic. The titular island is the largest in the group at about 100 square kilometers. Those hoping to visit will have to get there by a week-long boat ride from Cape Town. The island's government gleefully notes that it takes longer to get there than it takes astronauts to get to the Moon.
The marine protection zone will cover 627,247 square kilometers (over 242,000 miles) of the ocean around the islands. It will be the "gold standard" in ocean conservation, with neither fishing nor other extractive activities allowed, often referred to as "no-take." It will be the largest no-take zone in the Atlantic, and the fourth largest anywhere in the world.
The zone includes small areas just off the inhabited islands in which sustainable fishing will be allowed, but these areas are a small fraction of the no-take area's size. Given the historical reliance of the island's economy on the sea, this consideration is quite understandable.
These protected areas join many others covered by the United Kingdoms' Blue Belt Programme of marine protection, which aims to preserve 30 percent of the world's oceans by 2030.
In a press release issued by the government of Tristan da Cunha, the chief executive of the Royal Society for the Protection of Birds, Beccy Speight, left no doubt as to the environmental significance of this protection zone:
"This is a story two decades in the making, starting with the RSPB and Government of Tristan da Cunha commencing a conservation partnership, and culminating in the creation of this globally important protected area," Speight said. "The waters that surround this remote UK Overseas Territory are some of the richest in the world. Tens of millions of seabirds soar above the waves, penguins and seals cram onto the beaches, threatened sharks breed offshore and mysterious whales feed in the deep-water canyons. From today, we can say all of this is protected."
Speight added that in 2020, the need for these protections is greater than ever. "While Tristan da Cunha may be far away in distance it is still close to our hearts and protecting it is still the UK's responsibility. Closer to home, the crisis facing nature is also huge. So huge that our wellbeing, our economic future, and our very survival depend on the choices we make now about the natural world." Speight also used the statement to issue a call to action. "We need politicians to emulate the leadership of this small community to help us build the world we all want to live in. We hope today's fantastic announcement is the first of many more that help revive our world."
For the less romantic, there are also human-centered reasons why we ought to protect the oceans. A recent study suggests that keeping fishing boats out of a mere five percent of the ocean can raise catches everywhere else by a 20 percent. As it turns out, protecting the planet we live on provides benefits.
Most important of all, what animals are protected by this?
The now protected fish that inhabit the waters are a vital food source for many kinds of animals, all of which will benefit from not having to share their food supply with humans.
The vast area is home to many species of whales, sharks, and seals. Endangered species of albatross also drop by. Many birds that live on the islands and cannot be found elsewhere, such as the Wilkins bunting and the Inaccessible rail, also stand to benefit from the new protections.
Most adorable of all, the endangered northern rockhopper penguins make a home on one of the archipelago islands. With luck, they may not be endangered much longer.
Researchers find a key clue to the evolution of bony fish and tetrapods.
- A new study says solar and lunar tide impacts led to the evolution of bony fish and tetrapods.
- The scientists show that tides created tidal pools, stranding fish and forcing them to get out of the water.
- The researchers ran computer simulations to get their results.
Tides influenced by the sun and the moon were likely the reason why fish developed limbs and early tetrapods evolved, found new research.
The groundbreaking study took a look at tides during the Late Silurian—Devonian periods, which happened between 420 million years ago and 380 million years ago.
The scientists built their work on the theory that the Moon's mass and specific location along its orbit can greatly affect vast tidal ranges across Earth and can create tidal pools. Because they are isolated from each other, the pools provided the biological motivation for fish stranded by high tides to eventually grow limbs.
The study involved researchers from UK's Bangor University and Oxford University as well as Uppsala University in Sweden. They devised very detailed numerical simulations that proved the existence of large tides during the period they studied. They are first to tie tidal hydrodynamics to an evolutionary biological event, states the press release from the University of Oxford.
To come up with the simulations, the scientists employed paleogeography, the study of historical geography, to reconstruct the Earth's continents within the numerical model. The calculations showed tides over four meters happening around the South China block. That area holds the known origin site of the earliest bony fish we know and has been a treasure-trove of the earliest fossils of that nature. Geological evidence also supports changes in tides to be lined to these fossils.
Neil deGrasse Tyson Explains the Tides
"Large tidal ranges could have fostered both the evolution of air-breathing organs in osteichthyans to facilitate breathing in oxygen-depleted tidal pools, and the development of weight-bearing tetrapod limbs to aid navigation within the intertidal zones," states the paper.
The researchers believe further tidal simulations from early Earth can be used to recreate that far past with greater detail. The findings can help us understand more what roles tides played in diversifying early vertebrates or in causing extinction events.
Check out the study published in Proceedings of the Royal Society A.