Considering how much sharks are feared by humans, it is a bit of a surprise that scientists don't know much about the predators. For example, until recently, sharks were thought to be solitary creatures searching the seas for food on their own. Now it appears that some sharks are quite social.
Another mystery is how these prehistoric swimming and eating machines digest food. Although scientists have made 2D sketches of captured sharks' digestive systems based on dissections, there is a limit to what can be learned in this way. Professor Adam Summers at University of Washington's Friday Harbor Labs says:
"Intestines are so complex, with so many overlapping layers, that dissection destroys the context and connectivity of the tissue. It would be like trying to understand what was reported in a newspaper by taking scissors to a rolled-up copy. The story just won't hang together."
Summers is co-author of a new study that has produced the first 3D scans of a shark's intestines, which turns out to have a strange, corkscrew structure. What's even more bizarre is that it resembles the amazing one-way valve designed by inventor Nikola Tesla in 1920. The research is published in the journal Proceedings of the Royal Society B.
What a 3D model reveals
Video: Pacific spiny dogfish intestine youtu.be
According to the study's lead author Samantha Leigh, "It's high time that some modern technology was used to look at these really amazing spiral intestines of sharks. We developed a new method to digitally scan these tissues and now can look at the soft tissues in such great detail without having to slice into them."
"CT scanning is one of the only ways to understand the shape of shark intestines in three dimensions," adds Summers. The researchers scanned the intestines of nearly three dozen different shark species.
It is believed that sharks go for extended periods — days or even weeks — between big meals. The scans reveal that food passes slowly through the intestine, affording sharks' digestive system the time to fully extract its nutrient value. The researchers hypothesize that such a slow digestive process may also require less energy.
It could be that this slow digestion is more susceptible to back flow given that the momentum of digested food through the tract must be minimal. Perhaps that is why sharks evolved something so similar to a Tesla valve.
What is Tesla's valve doing there?
Above, a Tesla valve. Below, a shark intestine.Credit: Samantha Leigh / California State University, Domi
Tesla's "valvular conduit," or what the world now calls a "Tesla valve," is a one-way valve with no moving parts. Its brilliance is based in fluid dynamics and only now coming to be fully appreciated. Essentially, a series of teardrop-shaped loops arranged along the length of the valve allow water to flow easily in one direction but not in the other. Modern tests reveal that at low flow rates, water can travel through the valve either way, but at high flow rates, the design kicks in. According to mathematician Leif Ristroph:
"Crucially, this turn-on comes with the generation of turbulent flows in the reverse direction, which 'plug' the pipe with vortices and disrupting currents. Moreover, the turbulence appears at far lower flow rates than have ever previously been observed for pipes of more standard shapes — up to 20 times lower speed than conventional turbulence in a cylindrical pipe or tube. This shows the power it has to control flows, which could be used in many applications."
A deeper dive
Summers suggests the scans are just the beginning. "The vast majority of shark species, and the majority of their physiology, are completely unknown," says Summers, adding that "every single natural history observation, internal visualization, and anatomical investigation shows us things we could not have guessed at."
To this end, the researchers plan to use 3D printing to produce models through which they can observe the behavior of different substances passing through them — after all, sharks typically eat fish, invertebrates, mammals, and seagrass. They also plan to explore with engineers ways in which the shark intestine design could be used industrially, perhaps for the treatment of wastewater or for filtering microplastics.
It could fairly be said, though, that Nikola Tesla was 100 years ahead of them.
Dumpster-diving trash parrots
In a study about these smart birds just published in Science, researchers define animal culture as "population-specific behaviors acquired via social learning from knowledgeable individuals."
Co-lead author of the study Barbara Klump of the Max Planck Institute of Animal Behavior in Konstanz, Germany says, "[C]ompared to humans, there are few known examples of animals learning from each other. Demonstrating that food scavenging behavior is not due to genetics is a challenge."
An opportunity presented itself in a video that co-author Richard Major of the Australian Museum shared with Klump and the other co-authors. In the video, a sulphur-crested cockatoo used its beak to pull up the handle of a closed garbage bin — using its foot as a wedge — and then walked back the lid sufficiently to flip it open, exposing the bin's edible contents.
Major has been studying Cacatua galerita for 20 years and says, "Like many Australian birds, sulphur-crested cockatoos are loud and aggressive." The study describes them as a "large-brained, long-lived, and highly social parrot." Says Major, "They are also incredibly smart, persistent, and have adapted brilliantly to living with humans."
(Research regarding some of the ways in which wild animals adapt to the presence of humans has already produced some fascinating results and is ongoing.)Clever cockie opens bin - 01 youtu.be
The researchers became curious about how widespread this behavior might be and saw a research opportunity. After all, says John Martin, a researcher at Taronga Conservation Society, "Australian garbage bins have a uniform design across the country, and sulphur-crested cockatoos are common across the entire east coast."
Martin continues, "In 2018, we launched an online survey in various areas across Sydney and Australia with questions such as, 'What area are you from, have you seen this behavior before, and if so, when?'"
Word Gets Around
Credit: magspace/Adobe Stock
Although the cockatoos' maneuver was reported in only three suburbs before 2018, by the end of 2019, people in 44 areas reported observing the behavior. Clearly, more and more cockatoos were learning how to successfully dumpster dive.
As further proof, says Klump, "We observed that the birds do not open the garbage bins in the same way, but rather used different opening techniques in different suburbs, suggesting that the behavior is learned by observing others." One individual bird in north Sydney invented its own method, and the scientists saw it grow in popularity throughout the local population.
To track individual birds, the researchers marked 500 cockatoos with small red dots. Subsequent observations revealed that not all cockatoos are bin-openers. Only about 10 percent of them are, and they are mostly males. The other cockatoos apparently restrict their education to a different lesson: hang around with a bin-opener, and you will get supper.
Thanks to the surveys, the researchers consider the entire project to be a valuable citizen-science experiment. "By studying this behavior with the help of local residents, we are uncovering the unique and complex cultures of their neighborhood birds."
Vast expanding clouds and fireballs eclipsed their surroundings and smothered everything in their path, dropping radioactive material that gave rise to the title monster. I had never encountered anything like this. I appreciated the creativity of those 90s films that tried to push visual boundaries through emerging computer technology, but this was on a different scale. I later discovered that there was a good reason for this – the footage was real.
The film did win awards for its special effects, although that was for the giant lizard itself and scenes of New York landmarks being shattered by its rampage, not the precise origin or significance of those fleeting mushroom clouds.
I kept coming back to those images and the accompaniment of haunting, almost other-worldly, choral music. It sent shivers down my spine, and still does every time I re-watch it.
It was that footage which started my journey towards research into nuclear history, and which led to me becoming a visiting fellow at the British Library's Eccles Centre for American Studies, where I study their collections, including the early pictorial history of nuclear testing.
Many of those iconic images which originally stunned me came from the aptly named Operation Crossroads – an exercise 75 years ago involving the first postwar nuclear weapons tests in July 1946, conducted by a joint US army-navy task force in Bikini Atoll in the Pacific. It involved 42,000 people, around 150 support vessels and over 90 target ships and submarines.
It also used over half the world's supply of film footage and hundreds of cameras to capture the nuclear detonations. Officially, this extensive filming was driven by military policy and scientific considerations, US political and military leaders wanting to understand the effects of this new weapon. At the same time, the demonstration of these weapons on film also served to showcase US power to a global audience.
The literal and psychological shock waves of that event were significant in the early cold war and in shaping the modern world, from setting precedents for thousands of subsequent bomb tests and accelerating the arms race to long-lasting radioactive environmental damage in locations where these tests occurred.
Crossroads even led to the invention of a language of terms to describe nuclear testing (through over two months of negotiation). Some terms agreed on are perhaps less familiar, including “cauliflower cloud" and “base surge", while others (like “fallout") have become ubiquitous since.
Crossroads had such an impact because it was almost a blockbuster movie production in its filmic scale and focus – a military-scientific cinematic spectacle, unique among over 2,000 nuclear tests conducted worldwide by all nations since.
Public Domain (Wikicommons)
Even as much of its cold war origins and significance lie forgotten, Crossroads' cinematic legacies have lived on over the last 75 years. Photos and footage from it have been used widely, from propaganda to popular culture: from Godzilla movies to internet
memes. It has been employed to inform, to protest, as cultural symbols, and in ways which have obscured or re-framed aspects of nuclear history, shifting away from legacies of US testing, or even making the bomb a monster-destroying weapon (seen not least through Godzilla), much like a mushroom cloud enveloping everything in its path.
The world's most expensive film shoot
Crossroads fundamentally changed the film profile of atom bombs. Still images of those dropped on Hiroshima and Nagasaki in 1945 had appeared in many newspapers, but there was limited camera footage of these. There were also only a few thousand TVs in the US in 1946, so for many the Crossroads footage would be watched in cinema newsreels (whether in the US or other countries).
The Crossroads plan was large in scale and complexity, but underpinned by one central concept: assembling a fleet of around 90 decommissioned US naval ships (including three captured German and Japanese vessels), anchoring them in a remote lagoon in the Pacific (Bikini Atoll) and setting off atom bombs against them. A truly blockbuster plan.
'Operation Crossroads. Underwater atomic blast again rocks Bikini Atoll', British Pathé newsreel, 1946.
The stated goal was to test how atomic bombs would affect naval vessels, better to improve the design of future ships and such defensive arrangements as anchoring them in harbours, in the event that America faced the atom bombs of other nations in the future – though only the US had the bomb at this time. But Crossroads was later widened to test damage to other types of material and equipment, as well as measuring various effects of the weapons, such as (rather unsettlingly) the biological impact on thousands of animals present on target ships, including pigs, goats and rats.
Crossroads has been described as one of the most photographed events in history, and this had had several practical effects for moviemakers, even before the first weapon had been exploded. As more than half the world's available stock of film footage was bought up for cameras to record the tests, there were months of shortages in Hollywood and other major studios around the world.
New high-speed cameras were used to capture even the first fractions of a second after detonation (although these didn't always go to plan). Subsequent nuclear tests prompted further developments of these technologies, some of which would later make their way into fields from commercial cinematography to medicine.
Some of the first drone cameras – a concept evoking images of 21st-century movie-making – were also significantly developed and used in Crossroads. Large four-propeller engine B-17 bombers were rigged with TV cameras and transmitters so that they could be flown remotely as drone aircraft, to film the explosions and to collect radioactive samples from clouds. Similar arrangements were made for small, un-crewed boats. While a far cry from modern military and civil drones, such experiments were groundbreaking, leading to shots that would previously have been impossible, and laying foundations for future developments in both drones and in remote-controlled photography.
Development of the atomic bomb had been shrouded in the utmost secrecy throughout the second world war, to the point that the public and most members of Congress didn't know about it until after Hiroshima was bombed. Even Harry Truman – as vice president – hadn't known of its existence until he succeeded President Roosevelt in April 1945. This made the widespread publicity of Crossroads as a global media event one year later even more remarkable. Observers were invited to attend the tests from such unlikely places as the Soviet Union.
While the visuals of nuclear tests may be well recognised, the sound adds another dimension to their impact. The orchestras of the US Armed Forces provided custom music for films of the tests, whether for classified or public consumption, akin to the dramatic soundtracks of action or superhero adventures, or the eerie music of horror movies that creates the atmosphere.
The music was usually reserved as rousing chords for the opening and ending, or particularly poignant moments, such as observing damage to ships, though not for the detonations themselves. By contrast, all cinematic and documentary uses of Crossroads almost always overlay detonation footage with dramatic music.
Crossroads Baker detonation, with added music and with commentary by William Shatner, as featured in the revised version of the 1995 documentary 'Trinity and Beyond'.
One of a kind
“Those black dots are battleships? But they're so tiny," was the amazed reaction of one student when I showed their class footage from Crossroads – it was by no means an isolated response. The iconic nature of those images partly stems from Crossroads being distinctive among nuclear tests, particularly the second detonation, Crossroads Baker, on July 25 1946.
Almost all nuclear weapons tested have either been detonated within the atmosphere (ground or air, sometimes on the verge of space), in which case the first sign of the explosion has involved a blinding flash obscuring everything, or underground, in which there was often much less to see, except eerie videos of the earth slowly giving way to form a crater before kicking up dust. Underground testing could, of course, still lead to dramatic (and disturbing) footage, such as the ground rising up before exploding, a particularly notable example being the Operation Storax Sedan detonation in 1962, which was testing (almost unbelievably) ways of using nuclear weapons for civil construction in large excavation projects.
Crossroads Baker, meanwhile, was detonated just underwater, meaning it could be observed from the moment the explosion reached the surface. The visual effect was also made all the more powerful by the surrounding lagoon, the rapidly expanding blast hurling what were later estimated to be over two million tonnes of water and spray high into the air.
Silent footage from a ground angle with a clear view of the Crossroads Baker detonation, showing the growth of the explosion.
The scale of subsequent test series was different. While the bombs increased in power hundreds of times after Crossroads (and tests grew from using two weapons to sometimes up to 30 or 40 in a single operation), never again was there such a fleet assembled to be bombed.
Filming of tests became an industry in its own right, with subsequent tests having an entire US Air Force studio at Lookout Mountain Laboratory being dedicated to them. But there was rarely the same gathering of news media or scale of filming as at Crossroads. Footage of later tests, while still released in some propaganda and news films, also became less public for various reasons, including security.
There were no further underwater tests until 1955 with Operation Wigwam, which examined a concept originally planned for the cancelled third Crossroads test, Charlie, on the effects of deep ocean nuclear explosions against submarines. Wigwam similarly saw no repeat of the Crossroads fleet – only three miniature submarines anchored to the bomb for taking damage measurements, alongside a modest number of support vessels.
Other stories
For all the effort of being so widely photographed, much of the footage captured remained classified. Some was released in 1946 newsreel and public information films, more appeared in the 1960s, and further photographs and footage were released in 2016.
Crossroads had a book as well: an “Official Pictorial Report", something not repeated in any other test series and publicly available with around 200 photographs and captions. It has been a very valuable and often-overlooked time capsule of how the test was recorded and presented, but is also only a drop in the lagoon of 50,000 still images captured.
Many photos are of the people involved rather than the bombs themselves. In the Official Report, for instance, I discovered that only a fifth of the images show mushroom clouds; the rest charting things like scientific preparations or the aftermath of tests, but also everyday life for the task-force members conducting them. The more I saw them, the more I became fascinated with how these people were adapting to living through such events. It was like seeing “behind the scenes" footage.
And then there are the people who are only represented briefly in these images, often in a particular light, or excluded entirely – such as the existing population of 167 people at Bikini Atoll. These people ostensibly “agreed" to give up their homes for science, but, in reality, felt that they didn't have a choice, and also assumed that the move would only be temporary.
This was one of the first examples of nuclear colonialism. They were relocated to Rongerik Atoll, where food sources turned out not to be sustainable, and relocated further times after that. About 150 returned to Bikini in the 1970s, but the health dangers from radioactivity left behind by subsequent tests meant they had to leave again in 1978 and have never been able to return. Their story only received the greater attention it deserves in recent years.
In the world of box office films, the predominant cinematic uses of Crossroads' historic footage remains the mushroom cloud, inescapable in its iconic and instantly recognisable form. But the ways in which it has been used out of context in such films as Godzilla can create new meanings for how others depicted nuclear history, while further obscuring the original ones.
Admiral William Blandy, who led Operation Crossroads, and his wife cut a mushroom cloud cake. ( Harris & Ewing Studio/Wikimedia Commons)
(Mis)appropriation of Crossroads
Crossroads' footage has been used in a wide variety of settings, from the ending of Stanley Kubrick's Dr Strangelove to YouTube memes. But the Godzilla uses stand out, both in my own personal experience, but also because of their significance of wider trends in how nuclear history has been re-interpreted cinematically.
Even in 1998, I saw Godzilla as an allegory for the effects of nuclear tests and radiation. It was only when reading about the 1954 original that I learned the wider history: in the original (Japanese) story, Godzilla is an embodiment of the harm from nuclear weapons themselves and particularly the atomic bombings of Hiroshima and Nagasaki. The 1954 Godzilla was a peaceful ancient dinosaur, sent on a rampage by the effects of radiation from an atomic explosion. But this narrative became distorted in some later remakes, whether aimed at Japanese or western audiences.
A particular criticism of US adaptations, right from US re-cuts of the 1954 original that were sold back to Japan, has been the removal of overt references within the movies to Hiroshima and Nagasaki, or indeed to any of the problematic aspects of US nuclear history.
The 1998 film begins by focusing on Godzilla as being created by French nuclear tests in the Pacific. Such detonations did indeed happen, although the footage used is entirely that of American Pacific nuclear testing (Crossroads Baker featuring prominently from different angles alongside a few shots of other tests). Little visual and audio cues reinforce this fiction by superimposing over a montage of test preparations a map of French Polynesia, a countdown in French, and La Marseillaise playing in the background.
There are other hints later in the film which – as subtle as the presence of Godzilla itself – include Jean Reno as leader of a “French Secret Service" team who signals their job is to clean up the problems created by their country's tests in the Pacific, and a US TV station helpfully putting up a map of Godzilla's origins alongside a big sign “French Nuke Testing".
The 2014 film goes even further in its repainting of nuclear testing history. The opening also starts with Pacific tests, although framed as being the 1954 US thermonuclear weapons test, Castle Bravo. This time, instead of starting with a Godzilla created by atom bomb radiation, the nuclear tests are portrayed as a weapon used to try to kill Godzilla.
Opening shots of Godzilla (2014), prominently featuring footage of the Crossroads Baker detonation.
Of course, it's ironic that the film starts with an attempt to kill the embodiment of the effects of nuclear weapons, Godzilla, with nuclear weapons. And that the real-life 1954 Castle Bravo test went out of control because of an unexpected reaction, spreading radiation much further than planned, severely affecting the population of the Rongelap and Utirik Atolls with radiation poisoning, as well as sailors on a Japanese fishing trawler, one of whom later died. This story of the fishermen ignited protests in Japan over nuclear testing, resonating with the still fresh wounds of Hiroshima and Nagasaki and acting as a major inspiration for the original Japanese Godzilla film that same year.
For all the advancements in special effects technology, at the crucial moment of detonation, the iconic footage of Crossroads Baker still appears as the centrepiece in the 2014 Godzilla. It is interspersed with a more computer-generated mushroom cloud and the mimicking of shock waves hitting island beaches, but the continued usage shows its cinematic longevity.
It is not that there weren't videos of Castle Bravo available. On the contrary, footage of it has been iconic, and terrifying, in its own right in documentaries and films, and that bomb itself was over 700 times more powerful than Crossroads Baker. It is possible that these films, taken from a greater distance, didn't have quite the same, seemingly close-up, unobscured, and immediate feeling of scale as Baker, flanked by full-sized naval ships that appear as mere toys against the mushroom cloud.
To stunned moviegoers like myself, Crossroads may well have been the most expensive special effects in history. Adjusted for inflation, the operation would have cost over US$800 million in 1998, possibly even more with added technical and safety complexities (fortunately, US and Soviet atmospheric nuclear testing had ended in 1962). As such, those few seconds of nuclear explosion opening shots in Godzilla alone required more than 6.5 times the entire budget of the monster movie they ended up in.
But the cost which can never be calculated is the power of those images upon the human imagination and fear, as well as their effect on the nuclear arms race. Many target ships, while damaged, survived Crossroads Baker, but were enveloped in so much radioactive seawater that decontamination became almost impossible, except for a few vessels.
Plans to sail the remaining ships back to the US triumphantly gave way to sinking most of them, albeit without the same fanfare as the operation itself. A forgotten end credits scene on which the cameras never rolled, but the fallout from which fogs the films to this day.
Timothy Noël Peacock, Lecturer in History, University of Glasgow
This article is republished from The Conversation under a Creative Commons license. Read the original article.
