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Writers, artists, and engineers have long marveled at the nautilus's beauty and swimming abilities.

The chambered or pearly nautilus is a cephalopod (a type of mollusk)-a distant cousin to squids, octopi, and cuttlefish. Unlike its color-changing cousins, though, the soft-bodied nautilus lives inside its hard external shell. The shell itself has many closed interior chambers or "compartments."

The animal resides in the shell's largest chamber, while the other chambers function like the ballast tanks of a submarine. This is the secret to how the nautilus swims.

The tissue in a canal called the siphuncle [sigh-funk-el] connects all of the interior chambers. As seawater pumps through the living chamber, the nautilus expels water by pulling its body into the chamber, thereby creating jet propulsion to thrust itself backwards and to make turns. While swimming up or down through the water column, the nautilus uses its siphuncle to suck fluid into, or draw it out of, the smaller sealed chambers, allowing the animal to adjust its overall buoyancy.

According to fossil records, animals similar to the chambered nautilus have existed for about 500 million years. Although no regulations currently exist to protect them, the six living species of chambered nautilus appear to be in decline. They are trapped mostly for their attractive shells and also for the shell's inner layer, called nacre, which is used as a pearl substitute in jewelry and trinkets. In 2013, NOAA Fisheries funded a University of Washington researcher to conduct population studies of the nautilus in Fiji and American Samoa. The research should provide a clearer picture of nautilus abundance in those areas.

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The ancient Greeks saw the chambered nautilus shell as a symbol of perfection. The shell can be described mathematically as a logarithmic spiral.

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national oceanic and atmospheric administration

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The chambered or pearly nautilus ( Nautilus pomilius ) is a type of cephalopod-a distant cousin to squids, octopi, and cuttlefish. Unlike its color-changing cousins, though, the soft-bodied nautilus lives inside its hard external shell. The shell itself has many closed interior chambers or "compartments.".

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Paleo-art - New Visions of Ancient Creatures

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Paleo-art - New Visions of Ancient Creatures

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Want more paleoart? Listen to Gabriel Ugueto on Science Friday and explore a visual guide of his illustration process. Learn how dinosaurs walked with Science Friday Educate, and see how puppeteers brought dinosaurs to life on stage.

Paleoartist and scientific illustrator Gabriel Ugueto has a golden rule for his work: Accuracy. And he says that’s not to be confused with realism.

“Accuracy, based on what we know, is one of the most important things I can showcase in my work,” he says, “and we do what we can with the evidence that we have so far… Realism is very difficult because we don’t know exactly what these animals looked like. It’s just all suggestions and interpretations.”

As a paleoartist, Ugueto reconstructs and illustrates prehistoric animals that aren’t around anymore. You might see his work in books, museums, documentaries, or even scientific journals that deal with extinct animals.

[Why do dinosaurs matter, anyway?]

In order to resurrect the dinosaurs and other ancient creatures, Ugueto begins with a single bone and works his way from inside out. He researches whether there are any related animals alive today, or existing fossils that may shed light on how the bone fragment fits into a larger piece, and reconstructs the entire skeletal system. He then sketches in muscle groups, and adds skin and color considering where the animal lived and during what period of time.

But his resulting illustrations often don’t match the Jurassic Park-inspired dinosaurs that we’re used to.

“I think there’s a big boom in paleoart right now, because there are a lot of recent discoveries and science is allowing us to look at dinosaurs in a whole different way,” Ugueto says. “We know now what coloration they could have had. We know a lot more about the way they were related to each other. We know now more than ever about how they could have behaved, who they are related to… There is a huge renaissance to make these animals more accurate.”

Enjoy Ugueto’s reinterpretations of some of the prehistoric animals that we thought we knew so well:

Plesiosaurs

Polycotylus. Image courtesy of Gabriel Ugueto.

Until recently, Ugueto explains, people thought that plesiosaurs had smooth, taut skin. Then, researchers unearthed a “beautifully preserved” plesiosaur in Mexico.

The finding revealed two new discoveries: Skin impressions revealing tiny scales, and blubber-like deposits around the body, particularly around the tail and neck.

“I think, for a long time, paleoart suffered from skin-wrapping everything,” Ugueto says. “We didn’t give any room for fat deposits, muscles, and everything looked really like the animals were anorexic… but we have to keep in mind that they were alive.”

[Looking for some micrometeorites? Check the roof.]

Theropods

Geminiraptor. Image courtesy of Gabriel Ugueto.

We may now know that birds are modern dinosaurs, but the feathers they sport go way back—and they didn’t always appear only on the dinos that flew.

“We have evidence for many, many groups of non-avian dinosaurs that they had feathers,” says Ugueto. And these dinosaurs had plenty of different types of feathers, he explains, from very simple ones that look more like hair  to the types of feathers that can be still found on birds like pigeons today.

“But we don’t know exactly where the origin of feathers started,” he explains. “And some people even think that pycnofibers are present on pterosaurs, which are those little hair-like structures, are probably homologous with feathers. So if that is the case, then the ancestor of both pterosaurs and dinosaurs had feathers or some sort of feather-like integument.”

Tyrannosaurus rex

Tyrannosaurus rex. Image courtesy of Gabriel Ugueto.

Perhaps the most commonly-depicted dinosaur, Tyrannosaurus rex is usually shown as a terrifying, glamorous, photogenic lizard. But in reality, the mighty T. rex  was a bit scruffier around the edges than you’ve been lead to believe.

“What I learned is that you have to be really careful how you reconstruct teeth,” says Ugueto. Like humans, dinosaurs periodically lost some teeth. But unlike humans, they grew new ones. Those perfectly aligned and filled sets of chompers that we may see in movies aren’t very accurate—Ugueto takes care to reconstruct dinosaurs with teeth in various stages of development.

And if this T. rex looks a bit grizzled, that’s because it likely was. “It is known that tyrannosaurs had a very violent social life,” says Ugueto. “They bit each other’s face frequently, and they have a lot of scars in the fossils.” When illustrating their heads, Ugueto takes care to depict the scarring from all those scuffles.

And finally, while tyrannosaurs were mostly scaly, that doesn’t meant that they didn’t have feathers on parts of their bodies, says Ugueto.

[From bones to blades, the history of ice skates.]

Deinocheirus

Deinocheirus. Image courtesy of Gabriel Ugueto.

When he’s not doing strictly paleontological work, Ugueto occasionally gets to flex his artistic muscles a little more, as in this illustration of an irritable deinocheirus, above.

In order to flesh out the pond scene, Ugueto infused some character into his resurrection, and imagined the deinocheirus defending its territory

“If you’ve ever been around swans or geese or ducks, you know they’re super cranky,” says Ugueto. “And a lot of times too, I think dinosaurs were probably cranky also, only with a lot more teeth and a lot more attitude and a bigger size.” In fact, the deinocheirus depicted above was about the size of a T. rex.

The deinocheirus was likely omnivorous or herbivorous, so Ugueto wanted to resurrect the deinocheirus as a creature that wasn’t predatory, but was “aggressive in the sense of defending its territory.”

Anurognathus

Agnur. Image courtesy of Gabriel Ugueto.

Sometimes, Ugueto’s recreations seem almost too astonishing to be true. When he brought this illustration of the Anurognathus to the printer, he had an exchange with the woman behind the counter, who couldn’t believe that such an animal had once roamed the earth. Ugueto compares this pterosaur called Anurognathus, depicted above, to a porg from The Last Jedi.

Ugueto says it’s easy for people to be surprised and amazed when they see his recreations. But the feeling goes both ways: “I think part of it is the rush of creating something that looks so bizarre, and it fuels your imagination to think, ‘What were they doing? How could they have behaved? What were those weird structures they had for?’” he muses.

Even for a paleoartist, the creatures can be surprising and amazing.

Correction 3/16/18: A previous version of this article implied that plesiosaurs and pterosaurs are dinosaurs. Plesiosaurs are marine reptiles, not dinosaurs, and pterosaurs, while closely related, are not dinosaurs either. We’ve clarified the language and regret the error.

Credits

Produced by Luke Groskin
Music by Audio Network
Illustrations by Gabriel Ugueto
Article by Johanna Mayer
Additional Images by Shutterstock and E. Frey

Meet the Producer

About Luke Groskin

@lgroskin

Luke Groskin is Science Friday’s video producer. He’s on a mission to make you love spiders and other odd creatures.

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Eight years ago, Stephen and Amelie Trice learned that their three-year-old son Troupe needed a new heart. After many months of perplexing symptoms-small size, low energy, enlarged liver-Troupe was diagnosed with restrictive cardiomyopathy, an extremely rare and deadly condition in which the heart is unable to relax between heartbeats.

There is no cure and very few treatments. Despite his doctors' attempts to manage his condition with medicine, Troupe's health deteriorated. Afraid of losing their son, the Trices sought the expertise of a cardiologist at Children's Hospital in Atlanta. The doctor sat the worried parents down and over two hours explained that Troupe needed a heart transplant. Amelie recalls, "With a diagnosis of certain death, our only option was to cross our fingers that we were going to get more time with a new heart." The Trices went back home to Alabama, explained what they had learned as best they could to Troupe, and waited. Two months later, the couple were out with friends when they got the call.

"Across the table [Stephen] yelled to me, 'Amelie, they got a heart for Troupe!' I didn't say goodbye or pay a tab. I literally picked up my purse, walked out of the restaurant, and got into the car." The next morning, Troupe was in surgery. Amelie, a registered nurse, knew that soon the surgeons would be cracking open their toddler's chest. Another thought weighed on her mind, too. "As I walked to the waiting room unable to stop the tears and the feeling of my knees buckling, I knew that somewhere a mother and a family was grieving for their baby."

Four weeks later, Troupe's heart was still not working as it should. Again, he was dying. Quickly, doctors found a second organ and performed an emergency surgery. This time the transplant took. Still, Amelie remains haunted. "I live with a complex ball of guilt and grief," Amelie says. "I benefited from someone else's pain."

At Troupe's tenth birthday celebration, while he skated with his friends, chatted up his family, and scarfed pizza, the heart of another child pumped blood into his lungs, through his body, and back again. But the Trices' could not relax. The family had learned that again they would need the generosity of another despairing family-their youngest son Henry would also need a new heart. Thankfully, last year, Henry received his match.

According to Stephen, when the Trice family began their relationship with the United Network for Organ Sharing, "the average wait for a child's heart was six months. The current average wait for a child of Henry's size is one year." In the United States, and worldwide, we face an organ shortage. Today, over 123,000 people in the U.S. are waiting for lifesaving organs, according to the network. Many patients will never receive a match.

Right now, only a human body can grow a complex human organ. Unlike relatively simple tissues such as bones and skin, to give a heart, the donor must be declared brain dead and the family must consent. According to Howard Nathan, the president and CEO of Gift of Life, the nonprofit group appointed by the U.S. government to match transplant donors with those in need, 2.4 million people die in the United States every year. About half die in acute care hospitals where organs can be obtained. Of that roughly 1.2 million people, only 1% are suitable for organ donation. "That's it," he says. "Only about 14,000 people in the entire United States are suitable for organ donation. 8,200 people last year were donors."

Faced with those numbers, scientists and doctors have begun to ask, what would it take to give a family like the Trices a pair of new hearts without guilt or delay? Currently, tissue engineering can provide simple, thin tissues including cartilage, skin, and bone. Larger, more complex organs like the liver and heart present much more formidable challenges. They are structurally intricate, contain many different cell types, and require an extensive network of blood vessels.

Some researchers are working to create useable organs within animals. Much of this work has focused on genetically engineering animals such as pigs to grow human-compatible organs. But while researchers have succeeded in engineering pig organs to express human cell-membrane proteins, over time, additional incompatibilities have emerged. Some which were implanted in non-human primates suffered from immune attacks. Others failed due to incompatibilities with blood clotting proteins, which can cause blockages in some places and uncontrolled bleeding in others.

The fact remains that today, if someone needs a complex organ, a human is required to provide it. But in the near future, perhaps, families may not have to live with conflicting emotions of guilt, grief, and joy. Maybe all that will be required are a knowledgeable team of dedicated people, a slurry of cells, and a printer.

Bioprinting in 3D

Around the time that Troupe Trice was undergoing surgery to receive his new heart, Dr. Thomas Boland at Clemson University secured a promising sounding patent: "Ink-jet Printing of Viable Cells."

Boland's patent relies on 3D printers, which can build complex shapes from little more than blueprints and the right type of material, including cells. An ink-jet printer that spits out three-dimensional objects works much like the familiar two-dimensional versions that sit on our desks-in fact, many started their "lives" printing paper. Like the 2D version, a 3D printer precisely deposits material drop by drop. But instead of feeding a sheet of paper past the print heads, a 3D ink-jet printer ratchets its platform down a notch and then deposits another layer atop the last. The "ink" can be virtually anything that can flow through a print-head and later harden-plastic, wood pulp, proteins, human cells. For 3D bioprinting, scientists fill the ink cartridges with cells and proteins instead of plastic.

There's also another promising 3D bioprinting technology, called stereolithography, which uses laser light to harden portions of a soup of polymers into a solid frame or "scaffold." When the machine is done, the excess liquid drains away to expose detailed supports. Researchers then bathe these scaffolds in cells and nutrients and wait for the cells to grow and remodel the scaffold to their liking.

Organovo's bioprinter creates tissue that mimics the structure and composition of various human organs.

Like many 3D printing techniques, 3D stereolithography was originally designed for more traditional manufacturing. There, the usual polymer materials are efficient, but unsuited to printing organs. "No matter how convenient the 3D printing technology may be, if there are toxicity aspects remaining, it is essentially useless for real life applications," says Sungho Jin, a professor of materials science at the University of California, San Diego.

Roger Narayan, a biomedical researcher at North Carolina State University, set out to make them biocompatible, so he substituted riboflavin-or vitamin B12-for the toxic polymer hardening substances.

In one set of experiments, he found that the structures were less toxic than glass, meaning the mixture would be suitable for implantable medical devices or possibly as scaffold for fine-featured organs. "What is unique about this technique," Narayan says, "is that it allows you to do 3D printing at submicron dimensions. You begin to be able to make structures that can interact with cellular or sub-cellular components."

That high resolution allows researchers to consider 3D printing tissue types that were too detailed for earlier methods. "Many tissues exhibit complex small-scale geometries that are difficult for engineering to mimic using conventional scaffold techniques," says Mohan Edirisinghe, a biomechanical engineer at University College London. "Complex scaffolds for many types of artificial tissues, including the kidney, the liver, and blood vessels, can be created using this approach."

Narayan's technique and its kin are still early in their development, but there is one company that's 3D printing tissues today. San Diego-based Organovo is using 3D tissue printing to create 3D printed "organs on a chip." Rather than spending time and money testing drugs on animals, organs on a chip will allow researchers to test immediately on human cells. Cells can come from a research cell line, a patient, or other sources such as stem cells. "These tissues will take the form of both normal health or diseased by design," says Michael Renard, executive vice president of commercial operations. Organovo's has released a 3D-printed liver tissue, and the company has partnered with the NIH to create tests for human eye tissue as well.

State-of-the-Art

Organovo liver tissues, while an impressive 20-30 cell layers thick, are not fully-functional organs, but they are a step toward that goal. Several challenges remain, Renard says, including "securing the proper cell types in the quantities needed to achieve the desired level of function and the integration of a vascular network necessary to maintain a healthy condition." These hurdles are shared by virtually anyone hoping to create complex human organs.

Robert Langer, a professor of chemical engineering at MIT, points out several other oft-forgotten limitations of 3D bioprinting. "Right now, we can't make any organ or tissue to function properly in humans other than skin. 3D printing hasn't even been used successfully for that. Making an organ also requires blood vessels, nerves, and cells to behave properly. 3D printing can't do that."

Recreating human vasculature, seen here in a 3D CT scan of a human heart, is difficult using current 3D printing techniques.

Still, the desire to print these organs drives much of today's 3D bioprinting research. Laboratories have successfully recreated human ears, noses, skull bones, jaw bones, tracheas, ears, noses, skin sections, bladders, arteries, and fat. Rather than cutting squares of healthy skin from a patient to help cover an injury, a 3D printer could print skin perfectly shaped to fit. Patients marred by disfigurement may soon be able to customize a nose on a computer.

While some 3D printed body parts, such as skull and facial implants, have shown success in human patients and have received FDA approval, others are still working their way from the laboratory into animal testing. Few tissues are ready for implantation. Size remains a problem, Renard says. Current technologies struggle to build tiny structures such as human retinas, capillaries, and ear cochlea, as well as large, complex organs like livers and lungs. If you need fine detail, it takes so long to build an organ that the cells die. If a researcher quickly prints a large organ from huge blobs of cells, she cannot engineer enough detail to provide blood vessels for the cells to survive, for example.

In many ways, the challenges of 3D organ printing mirror those of organ transplantation. As Nathan from Gift of Life points out, "When taken from a deceased person, tissues can be collected 24 hours after the heart stops, but organs need a blood supply." Without vasculature, cells do not receive nutrients and oxygen or excrete wastes beyond a thickness of a few layers. "One of the greatest challenges is ensuring that printed structures have an adequate supply of nutrients and oxygen until they can integrate with the body," says Dr. Anthony Atala, the director of the Wake Forest Institute for Regenerative Medicine.

Researchers have been scrambling to find ways to fix this plumbing problem. Strategies include layering cells on pre-made channels, leaving holes in tissues for blood vessels to grow, and adding chemicals that encourage blood vessel formation.

A stained sample of Organovo's 3D printed human liver tissue

Tissues are somewhat easier than organs. Cartilage, for example, does not need as much blood as other tissues, which is partly why Faiz Bhora, chief of thoracic surgery at Mount Sinai Roosevelt and Mount Sinai St. Luke's Hospitals in New York City, is working to 3D print a working trachea from stem cells. Bhora begins by using a gel that is hardened with UV light to create the scaffold. He then seeds the scaffold with stem cells and adds signaling compounds which instruct the cells to turn into cartilage. As a test, the team implanted a printed trachea into a baby pig. It is now a healthy adult. Bhora hopes to gain FDA approval of the first 3D bioprinted artificial trachea within three years.

At Cornell University, biomedical engineering professor Jonathan Butcher is working to build a functional human heart valve. His team starts with a goopy liquid the consistency of toothpaste that contains stem cells, hydrogels, and nutrients, and then they harden the liquid to the perfect stiffness using light. As he's perfected the system, Butcher has reduced the time required to build a heart valve from 14 hours-long enough for all the cells to expire-to under an hour. "One hour is more than enough. The cells don't really care about that," he says.

Rather than placing each cell in the valve exactly where it needs to go and telling each cell what it needs to do, Butcher is betting that if he puts the stem cells in the right environment, they will figure it out. As a part of the process, the cells are trained and tested in a machine that simulates human blood flow before they are implanted in an animal or human. "You have to figure out how to make this thing so that right when you implant it, it is working," he says. "We are pirating the natural engineering."

An Agonizing Wait

Thirty years ago, 3D printing was just an experimental technology capable of producing rudimentary objects. Today, researchers are cranking out organ scaffolds that are orders of magnitude more complex. While that progress has been remarkable, we still have a long way to go. We're nowhere near growing a little heart for a child like Trice or Henry, a liver for a beloved parent, or a kidney for a tiny infant, Atala says. "Based on our current work, we expect segments of bone, muscle and cartilage to be available within five to ten years. More complex structures, such as kidneys and livers, will obviously take much longer."

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That day cannot come soon enough for those who are waiting for organs, but for now they must hope for a human match. "I try not to worry about whether we will get one in time, and just continue on day to day," says Amelie Trice. Still, the promise of the technology makes her hopeful.

"My greatest wish is someone will grow a new healthy heart, customized to my children's immune systems and bodies, so we would never need a donor or medications that have so many side effects, and they could live long and happy lives naturally."

Image credits: Gordon Museum/Wellcome Images (CC BY-NC-ND), Courtesy Oganovo, Mark Riccio

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Eight years ago, Stephen and Amelie Trice learned that their three-year-old son Troupe needed a new heart. After many months of perplexing symptoms-small size, low energy, enlarged liver-Troupe was diagnosed with restrictive cardiomyopathy, an extremely rare and deadly condition in which the heart is unable to relax between heartbeats.

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Threddy Threddyrex GIF - Threddy Threddyrex Trampoline - Discover & Share GIFs

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Android early earthquake warnings

In California, Washington, and Oregon, we partner with the ShakeAlert® team to distribute alerts provided by their system. ShakeAlert uses a network of 1675 seismic sensors to detect earthquake shaking, and analyzes that data to determine the location and size of the earthquake. The ShakeAlert® system then sends a signal to Android Earthquake Alerts System, which then sends an earthquake alert directly to Android users.

Outside of these U.S. states, we use a crowdsourced approach to detect earthquakes. All smartphones contain tiny accelerometers that can sense vibrations and speed, signals that indicate an earthquake might be happening. If the phone detects something that it thinks may be an earthquake, it sends a signal to our earthquake detection server, along with a coarse location of where the shaking occurred. The server then combines information from many phones to figure out if an earthquake is happening. This approach uses the 2+billion Android phones in use around the world as mini-seismometers to create the world's largest earthquake detection network; the phones detect the vibration and speed of shaking of an earthquake, and alert Android users in affected areas accordingly.

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Earthquake detections can also be viewed on Google Search. Simply search for "Earthquake near me" - if you've felt shaking - to get additional information about any seismic activity near you.

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Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3

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Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3 https://t.co/9q4GLvLm9O

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Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3 pic.twitter.com/9q4GLvLm9O
— Dave Burke (@davey_burke) September 19, 2020

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Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3 https://t.co/9q4GLvLm9O

# data[].attributes.attachment_link.metadata.attachment_props.original_text
Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3 https://t.co/9q4GLvLm9O

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Android phones and #USGS gave Southern California residents an early warning to the 4.5 earthquake last night Here's what the phones' sensors, acting as seismometers, detected. Yellow and red concentric circles are expected locations of the P and S waves. https://t.co/duKZnnIjE3

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NOVA: Making Stuff Faster | The Math Behind Package Delivery | PBS LearningMedia

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Learn how UPS, a global package delivery company, has developed an algorithm to schedule routes for its delivery trucks in this video from NOVA: Making Stuff Faster. Host and technology columnist David Pogue examines how difficult it is to find the most efficient way to visit multiple locations-a mathematical challenge known as the "traveling salesman problem."

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Eagle Eye Structure and Vision | Eagle Power | PBS LearningMedia

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Watch a golden eagle find a target from a great distance, and learn about the anatomical characteristics of an eagle’s eyes that gives it excellent vision, in this video adapted from NOVA: Eagle Power. Use the video content as a basis for creating a model to test the limitations of an eagle’s eye st…

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Peregrine Falcon Adaptations - World's Fastest Animal

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Peregrine Falcon Adaptations - World's Fastest Animal

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Peregrine Falcon Adaptations | World's Fastest Animal | PBS LearningMedia

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Learn about the adaptations that make the peregrine falcon a highly effective aerial predator in these videos from NOVA: World's Fastest Animal. Use this resource to provide detailed observations of peregrine falcons and to exemplify how adaptive traits and behaviors increase an organism's chances to survive and thrive in their environment.

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Sunbirds’ dazzling feathers are hot, in both senses of the word

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Iridescent feathers reflect vivid colors. But they also become scorching hot in the sunlight, a study finds.

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Discover the possibilities of biotech from molecule to medicine with all-new high school curriculum and Professional Learning tools. Join Genentech and Discovery Education as we deepen student understanding of the full Product Life Cycle while exposing students to biotech industry trends, practical…

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Learn about the relationships among the Sun, clouds, and weather in this video excerpt from NOVA's Cloud Lab. The Sun heats Earth's surface unevenly, driving global weather patterns that carry heat and humidity around the world. Differences in air pressure result in wind, causing air masses with different temperature and humidity to move.

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We offer a small but growing collection of films that offer glimpses into the hearts and lives of scientists and aspiring scientists. These films reveal their passions, struggles, setbacks, and the prices many willingly pay to pursue their dreams and to do what they love.

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The Wonder of Science website aggregates the work of Paul Andersen around the NGSS (Next Generation Science Standards)

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Moth Mimicry: Using Ultrasound to Avoid Bats

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Moth Mimicry: Using Ultrasound to Avoid Bats | This video follows scientists as they uncover the ways in which moth species in Gorongosa National Park use ultrasound to avoid being eaten by bats.

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Ancient Math & Music | PBS LearningMedia

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Explore how Pythagoras and Plato found mathematics in music and nature in this video from NOVA: The Great Math Mystery. The ancient Greeks identified three pleasing musical intervals: an octave, a fifth, and a fourth. Pythagoras discovered that the beautiful musical relationship between the notes was also a mathematical relationship: the harmonious sounds are produced by vibrating strings with particular ratios of string length.

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Moth Mimicry: Using Ultrasound to Avoid Bats

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Moth Mimicry: Using Ultrasound to Avoid Bats | This video follows scientists as they uncover the ways in which moth species in Gorongosa National Park use ultrasound to avoid being eaten by bats.

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How did dinosaurs regulate their body temperatures?

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How did dinosaurs regulate their body temperatures?

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How Did Dinosaurs Regulate Their Body Temperatures?

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How Did Dinosaurs Regulate Their Body Temperatures | This activity extends concepts covered in the film The Origin of Birds. Students analyze and interpret data from a scientific paper to explore thermoregulation in living and extinct animals, including dinosaurs.

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Battle of the Weavers: Joro Spider vs. Golden Silk Orb Weaver | Coastal Georgia Botanical Gardens

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In the world of arachnids, spiders come in all shapes and sizes, showcasing a stunning diversity of colors, patterns, and behaviors. Among these fascinating creatures, the Joro spider and the Golden Silk Orb Weaver stand out as formidable and captivating representatives of their kind. Both renowned for their intricate web-building abilities, these spiders have unique characteristics that set them apart in the world of silk-spinning arachnids. Let’s delve into the duel between the Joro spider and the Golden Silk Orb Weaver.

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Joro Watch is a monitoring program to collect data and better understand the current spread and distribution of Joro spiders.

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From Dog DNA to Human Diseases | This video follows biologist Elinor Karlsson, who studies dogs to find genes associated with traits, including certain diseases.Due to a long history of selective breeding, dogs within a breed are almost genetically identical. This makes them ideal for finding genetic differences associated with traits of interest. Scientists focus on single nucleotide polymorphisms (SNPs): specific positions in the genome where nucleotides are known to vary among dogs. They can use SNPs to locate genes associated with diseases such as cancer, which may also inform human medicine.

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What van Leeuwenhoek Saw | This activity complements the animated short video Seeing the Invisible. Students explore concepts related to relative size and scale using cards of cells and microorganisms.

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Why world records are getting hard to beat according to math

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Why world records are getting hard to beat according to math

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New world records in some sports are remarkably elusive, yet in others they seem to fall regularly, as Armand Duplantis's extraordinary pole vault recently demonstrated. Looking to records in other areas such as climate change can help explain why.
To the roar of the crowd at the Athletics World Championships in Tokyo, Armand "Mondo" Duplantis sprinted down the runway with his pole aloft. Pumping music reached a crescendo and the cheers became deafening. Then Duplantis flew.

The Swedish pole vaulter soared above the competition to assert his dominance over one of athletics' most technical disciplines - achieving a new world record in the event. His 6.3m (20.6ft) leap saw Duplantis win his third consecutive world title and, astonishingly, break his 14th world record. He is, in every way, raising the bar again and again. ( Read more about how Armand Duplantis is reaching new heights from BBC Sport.)

This is often what can happen in sport. Improvements in diet, technique or equipment can bring a sudden spate of world records, especially in technical disciplines like pole‑vaulting and cycling where small adjustments make a big difference. Technical advances in running events have also seen records tumble in recent years.

In contrast, the men's world record in the long jump has been broken only once since 1968 when Mike Powell leapt 8.95m (29ft 4in) at the 1991 World Championships, also held in Tokyo. Perhaps we have reached peak long jump - a situation in which further improvement is impossible and differences between an athlete's performances come down to "luck": the wind, how well they slept the night before, and so on.

We refer to these sorts of situations as "stationary", in the sense that the overall trend in average behaviour is unchanging. Given a stationary system, we can ask how often we should expect records to fall due to random fluctuations. For an example of a stationary system on which we have long‑standing measurements, we might look to pre‑industrial climate data.

Records falling like rain

Imagine we investigate annual rainfall in different cities across the world, with the totals in each independent of the others and with no overall trend in climate behaviour. The first year's rainfall in each city is, by definition, a record. If the second year's rainfall is independent of the first, then on average, half the cities will see rainfall exceed the first year while in half it will not. So after two years the average number of records across the cities is one plus a half.

In the third year, a total must exceed both previous years to set a new record. On average, this happens in only one-third of the cities, so by the end of year three the expected number of records is one plus a half plus a third. And so the series continues. After 100 years the expected number of records per city is one plus a half plus a third plus a quarter... plus a hundredth.

This set of consecutive fractions added together is known in mathematics as the Harmonic series because of its connections to harmonies in music. It crops up in all sorts of places from stress testing in the construction industry to wartime logistics and from reliable shuffling in games of cards to the number of stickers you need to buy to complete your sticker book.

Although the terms we are adding on get smaller and smaller, the sum of the harmonic series does not settle to a fixed value - but instead keeps growing. In mathematics we say that the sequence diverges. This agrees with our intuition about records: even in stationary systems, new records will eventually occur if we wait long enough.

But as time goes on, the growth of the sum of the harmonic series becomes very slow, as you can see in graph below. This would mean we expect the frequency of record‑breaking to drop dramatically over time. We expect two records in the first four years, then a wait of about seven years for the next, then around 20 years for the next, and another 52 for the one after that. After a century we would expect roughly five records in total and after a thousand years, just seven.

Even in a stationary system we still expect records to be broken, but with decreasing frequency. Flipping that idea on its head, we can use data on how often records fall to indicate whether a system is stationary or not.

Decades of climate data, for example, show records are being broken at an alarming rate, suggesting our climate is rapidly warming and is no longer stationary due to the effect humans are having on the planet by emitting greenhouse gases into the atmosphere.

The rate at which record hot temperatures are being broken is declining more slowly than expected and has even started rising in the last 15 years. Cold records, by contrast, have fallen much faster than they would in a stationary climate. Both trends strongly indicate a warming climate.

Scientists use the ratio of actual record frequency to expected record frequency - the so-called record ratio - to characterise the extent of climate change. In the last 15 years, the record ratio for cold events has dropped to below 0.5, suggesting cold records are being broken half as often as we might expect. Contrastingly, by 2020 the hot record ratio had crept up above four, suggesting records are being broken four times as often as we would expect in an unchanging climate. The hot record ratio reached 6.2 in 2024, the warmest year on record, according to the World Meteorological Organization.

What does this mean for sport?

In athletics we don't typically have enough data to know if individual sports have reached this stationary state. Some studies have argued that data on peak sporting performance across a range of track and field events suggest that we are at or near peak physical performance and that we should now expect records to be broken with decreasing frequency. Others argue that human performance has yet to peak and will continue to improve.

The number of records Duplantis has smashed in recent years suggests that the technical pole vault event has likely not yet reached a stationary state. Conversely, long-standing records suggest the long jump may already be stationary or even regressing.

We must be careful not to draw too strong a conclusion about a lack of records in a particular sport though. The women's long jump record has stood even longer than the men's - Soviet athlete Galina Chistyakova leapt 7.52m (24ft 8in) in 1988. Modern attempts at beating this record haven't even come close.

Swimming too saw a substantial drop in the rate records were being broken after the ban on high-tech polyurethane swimsuits came into effect in 2010. The so-called "super-suits" reduced drag and increased buoyancy meaning a large number of records were broken in 2008 and 2009 when the suits were allowed, some of them standing to the present day. That the rate of record breaking has begun to increase again suggests that improvements in technique and pool environment may allow swimmers to continue to improve for some time to come.

Sometimes, however, it can come down to extraordinary individuals who push the limits of the sport. US swimmer Katie Ledecky has smashed 16 world records during her career and earlier this year set a new record breaking time for the 800m freestyle. With 14 world records to his name, it is fair to say Duplantis is another athlete who is setting new standards for what is possible.

But after a swelteringly hot and humid World Championships in Tokyo in 2025, World Athletics president Seb Coe acknowledged that climate change may force athletics to rethink its tradition of holding summer events. Notably Duplantis' was the only world record broken in Tokyo. With three quarters of athletes reporting that climate change and heat are negatively impacting their health and competition performance, we may find that climate change itself will alter the rates at which athletics records are broken.

In the meantime, we should cherish those world records that do come along - the athletes who achieve them have beaten the odds to do something truly special.

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Why world records seem to be getting harder to beat - according to maths

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New world records in some sports are remarkably elusive, yet in others they seem to fall regularly. There is a good mathematical reason why.

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Breaking Bioplastics: Decomp and the Carbon Cycle STEM Case

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Breaking Bioplastics: Decomp and the Carbon Cycle STEM Case

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Lesson Info for Breaking Bioplastics: Decomposition and the Carbon Cycle | ExploreLearning Gizmos

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Lesson info for Breaking Bioplastics: Decomposition and the Carbon Cycle. Is this plastic cup sustainable? As a plastics engineer, the student must create a plastic cup from renewable resources that returns its material to Earth’s carbon cycle through decomposition by living things.

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Modeling Disease Spread | This interactive module can be used to model infectious disease spread in a population using the SIR model. It includes background on the components of the SIR model and factors that affect the spread of disease, as well as two simulators for modeling disease spread on different scales. The Click & Learn contains the following main sections:

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Designing a more environmentally friendly rocket

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An Inside Look: SpinLaunch Flight Test #7

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Resources For Lesson Plan For Science | PBS LearningMedia

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Discover free resources designed for your lesson plan for science. Explore natural phenomena and scientific practices with videos, games, and activities for all grades.