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Discovery Channel
Discovery Channel

How Scientists Built a Shark-Following Robot for Shark Week

Discovery Channel
Discovery Channel

For all we know about sharks, there's still a lot we don't know about these animals that both fascinate and terrify us. Traditional tracking methods like satellite and acoustic tags have shed some light on shark behavior, but even they have their limitations.

That's where Shark Cam, an autonomous underwater vehicle, comes in. "A few years [ago], I was working with a scientist who loved the idea of trying to find out what some of these fish that we track do when we can’t follow them because they’re out of reach or they go deep or we disturb them when we get in the water," says marine biologist Greg Skomal. "We thought it’d be really interesting to develop some kind of robot that could track marine animals, specifically sharks. One of the principals at Big Wave Productions [which produces shows for Shark Week] was super excited about the concept and propelled it upwards to Discovery, and they loved it. So with their support, we were able to actually make this come to fruition."

The autonomous underwater vehicle (AUV) was developed by Skomal and scientists at the Oceanographic Systems Laboratory at Woods Hole Oceanographic Institution. It was deployed from a boat off of Chattam, Massachussets, last year, where it followed great white sharks as they swam along the coast. Shark Cam makes its debut in the Shark Week special "Return of Jaws" tonight at 9 p.m. EST on the Discovery Channel; we talked to Skomal about developing the robot and what it revealed that traditional tracking methods did not.

How long did it take to build and deploy Shark Cam?

We started the project in 2011, and were able to do some field trials in late 2011, and we had a pretty functional vehicle by the summer of 2012. So about a year of solid development. Most of that was software modifications by the engineers who run these robotic underwater vehicles.

When you’re building something like this, are you working from an existing platform or are you starting from scratch?

The Oceanographic Systems Laboratory at Woods Hole Oceanographic Institution has an existing group of vehicles that are autonomous—they’re completely untethered to the boat, and they can be programmed to do a variety of missions. So really, all we had to do was modify the software of one their existing vehicles in order to get it to follow a live shark.

It sounds simple, but it wasn’t. It was a partnership—[between the engineers and] me, having tracked fish for years, trying to give them a sense of what we anticipate the behavior of the shark to be, so that the vehicle can adjust to it. It’s one thing to have a vehicle go in a straight line, or even mow a lawn—back and forth, back and forth—but to have it adjust to the behavior of a live animal is a most complex process.

What kind of behaviors would they be adjusting for?

Changes in three-dimensional movement. Up, down, sideways, back, forth—you name it. Very few live animals swim in a straight line at one depth. So it had to basically adapt to random movements in three-dimensional space.

What technology did you outfit the robot with?

There were four cameras on Shark Cam—it was specially designed to carry three of those, and one mounted on top. It's battery-powered, which limits its life, but that’s fine, we can expand on that. It is modular in the sense that we can add components to it that do various kinds of things that we did not do [on this mission], like collect oceanographic data. It communicates with a transponder that we put on the shark to follow it and navigate and recreate the track of the animal.

We actually added a rear-facing camera, but because of the fine balance on the vehicle itself—it’s a torpedo and it has to be extremely hydrodynamic—throwing the extra camera on slowed it down. So that’s something that we have to develop in the next phase of this operation.

Robot with a view. Photo courtesy of the Discovery Channel.

When you decided you were going to take the Shark Cam out and put in the water and send it after a shark, you guys had to go out and tag the shark first. How did the robot work in conjunction with the acoustic tags?

We’ve been tracking white sharks with a variety of technology off the coast of Cape Cod for the last four summers. So [tagging the sharks was] almost the easiest part, since we’d already done the [research and development] to get that done. Once we got the transponder on the shark, the AUV was set to go.

Most acoustic transmitters emit a ping, and the ping is picked up by people in the tracking vehicle, so we can track the fish. But this acoustic tag is a transponder, so it has two-way communication between the vehicle itself and, in essence, the shark. So we can basically have a conversation that provides for highly precise navigation and mapping of three-dimensional movement. And that really is a step forward, because it’s not just passive acoustics where you’ve got a vehicle trying to just listen for something. [The AUV] was actually listening and communicating with [the tag].

We had to program the vehicle so that it could make decisions—very simple cause and effect decisions based on where the shark was, to follow it. We ended up getting a vehicle that can give us very precise tracks of the animal.

Were there any glitches you had to work out?

There was a whole series of glitches. The transponder itself is larger than we want it, but the funding simply wasn’t there to miniaturize it. So we had to use what we had. It turns out the orientation of the existing transponder design had to be vertical in the water column, which is absolutely counter to normal hydrodynamics. We had to figure out a way to get it to tow vertically on the shark, and that took a few days working with our tagging crew and the engineers. And that would allow for a stronger signal so that the AUV could actually keep up with the shark in shallow water.

We’re also in the natural environment. Where these white sharks hang out is a very dynamic area in terms of tide and current. So in many ways, we’re up against trying to get a vehicle that can only go, you know, six miles an hour to keep up with a shark that was swimming steadily at five miles an hour. And then it was the fine-tuning of the vehicle so that it could stay with the shark and not lose it.

How did the sharks react to it?

Jokingly, I told the engineers that once this big white shark sees this vehicle, painted bright yum-yum yellow, it was going to turn around and just eat it. Most would think that this voracious animal that is considered to be one of the most dangerous one on earth would not like to be followed so closely. So these guys got nervous every time the AUV got in close proximity to a shark.

But the shark completely ignored it. [At one point,] the shark actually turned around and did a big loop and started following the AUV, which I thought was fantastic. The AUV couldn’t do anything about it—it was hearing the shark behind it, and a major limitation of the technology is that it can’t do hairpin turns and quick circles. So that made for some good humor.

What did you learn by deploying this robot that you couldn’t learn just from using acoustic tags or satellite tags?

Every tag in technology has its ups and downs, and there’s no silver bullet when it comes to tags that gives you high resolution, broad scale, and fine-scale data on movement. Satellite tags are really good for looking at broad-scale movement—where the shark goes in broad migratory patterns. It doesn’t tell you a lot about fine-scale behavior.

Acoustic tags will tell you a little bit about fine-scale behavior, but only in the sense that you know where the shark is at any given time. One of the problems with the technology of acoustic tags—prior to us doing this—was instead of sending a robot after a shark, you follow the shark with your boat. And that’s usually limited by weather considerations, fuel, compatibility of crew members, provisions, all those things that can come up and go wrong. And the boat’s track doesn’t necessarily reflect the shark’s track, because the shark is going to be somewhere within a quarter or a half a mile from the boat. And it’s really hard to get a good, precise estimate of the actual movements of the shark in three-dimensional space using traditional tracking methods.

With the ability to send robots after the shark, you’re going to increase the precision of your tracking so you’ll know exactly what the shark did in three-dimensional space—the depth of water, the depth of the shark—and you’re collecting data at the same time over that same path. The vehicles can carry instrumentation on them—the simplest being water temperature, to complex instrumentation that measures current and tide—so you can determine whether the shark is swimming upstream or downstream. You can look at dissolved oxygen, so you can get a sense of what the minimal oxygen requirements of the shark are. You can also add other kinds of instrumentation that’ll answer questions about the habitat in which the shark lives.

So it’s a huge step forward—and when you throw cameras on the whole thing, you even have the potential for real behavioral observation: To see what the shark is doing. Let’s say it stops swimming and just stays in one area. If we approach it and put divers in the water, that’s going to spook the shark—and very few divers want to jump on top of a white shark to begin with. Or you speed up on it on a boat and you try to see what the shark is doing, but what if it’s 30 feet underwater? You can’t see what it’s doing. You send Shark Cam out, and you can record what’s going on in that area.

So the robot is a proxy for what we can’t do, and I think it’s a huge step forward in terms of advancing science and adding a new tool for marine scientists.

Have you used Shark Cam since?

We have not deployed the Shark Cam since last summer. The next step is going back to the drawing board—raising funding to tweak it and take it to the next level.

What's the next level?

The next level for us is to improve upon and learn from what we’ve already done. It’s a real solid analysis of the data, it’s fine-tuning the software to take into account sudden modifications in the shark’s behavior. It’s probably to integrate the camera systems a little better with the AUV so that we may be able to control them—turn them on, turn them off. It’s energy budgeting. And it’s really miniaturizing the transponder so that we can put it on much smaller sharks and maybe broaden its applicability.

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Scientific Reports, Fernando Ramirez Rozzi
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Stones, Bones, and Wrecks
Humans Might Have Practiced Brain Surgery on Cows 5000 Years Ago
Scientific Reports, Fernando Ramirez Rozzi
Scientific Reports, Fernando Ramirez Rozzi

In the 1970s, archaeologists discovered a site in France containing hundreds of cow skeletons dating back 5000 to 5400 years. The sheer number wasn't surprising—human agriculture in that part of the world was booming by 3000 BCE. What perplexed scientists was something uncovered there a few decades later: a cow skull bearing a thoughtfully drilled hole. Now, a team of researchers has released evidence that suggests the hole is an early example of animal brain surgery.

Fernando Ramírez Rozzi, a paleontologist with the French National Center for Scientific Research, and Alain Froment, an anthropologist at the Museum of Mankind in Paris, published their findings in the journal Nature Scientific Reports. After comparing the opening to the holes chiseled into the skulls of humans from the same era, they found the bones bore some striking similarities. They didn't show any signs of fracturing from blunt force trauma; rather, the hole in the cow skull, like those in the human skulls, seemed to have been carved out carefully using a tool made for exactly that purpose. That suggests that the hole is evidence of the earliest known veterinary surgery performed by humans.

Trepanation, or the practice of boring holes into human skulls, is one of the oldest forms of surgery. Experts are still unsure why ancient humans did this, but the level of care that went into the procedures suggests that the surgery was likely used to treat sick patients while they were still alive. Why a person would perform this same surgery on a cow, however, is harder to explain.

The authors present a few theories, the first being that these ancient brain surgeons were treating a sick cow the same way they might treat a sick human. If a cow was suffering from a neural disease like epilepsy, perhaps they though that cutting a hole in its head would relieve whatever was agitating the brain. The cow would have needed to be pretty special to warrant such an effort when there were hundreds of healthy cows living on the same plot of land, as evidenced by the skeletons it was found with.

Another possible explanation was that whoever operated on the cow did so as practice to prepare them for drilling into the heads of live humans one day. "Cranial surgery requires great manual dexterity and a complete knowledge of the anatomy of the brain and vessel distribution," the authors write in the study. "It is possible that the mastery of techniques in cranial surgery shown in the Mesolithic and Neolithic periods was acquired through experimentation on animals."

Either way, the bovine patient didn't live to see the results of the procedure: The bone around the hole hadn't healed at all, which suggests the cow either died during surgery or wasn't alive to begin with.

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iStock
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Animals
15 Incredible Facts About Pigeons
iStock
iStock

Though they're often described as "rats with wings" (a phrase popularized by the movie Stardust Memories), pigeons are actually pretty cool. From homing instincts to misleading rump feathers, here are 15 things you might not know about these avian adventurers.

1. THEY MIGHT BE THE FIRST DOMESTICATED BIRD.

The common city pigeon (Columba livia), also known as the rock pigeon, might be the first bird humankind ever domesticated. You can see them in art dating back as far as 4500 BCE in modern Iraq, and they've been a valuable source of food for thousands of years.

2. THEY WON OVER CHARLES DARWIN—AND NIKOLA TESLA.

Pigeon-breeding was a common hobby in Victorian England for everyone from well-off businessmen to average Joes, leading to some fantastically weird birds. Few hobbyists had more enthusiasm for the breeding process than Charles Darwin, who owned a diverse flock, joined London pigeon clubs, and hobnobbed with famous breeders. Darwin's passion for the birds influenced his 1868 book The Variation of Animals and Plants Under Domestication, which has not one but two chapters about pigeons (dogs and cats share a single chapter).

Nikola Tesla was another great mind who enjoyed pigeons. He used to care for injured wild pigeons in his New York City hotel room. Hands down, Tesla's favorite was a white female—about whom he once said, "I loved that pigeon, I loved her as a man loves a woman and she loved me. When she was ill, I knew and understood; she came to my room and I stayed beside her for days. I nursed her back to health. That pigeon was the joy of my life. If she needed me, nothing else mattered. As long as I had her, there was a purpose in my life." Reportedly, he was inconsolable after she died.

3. THEY UNDERSTAND SPACE AND TIME.

In a 2017 Current Biology study, researchers showed captive pigeons a series of digital lines on a computer screen for either two or eight seconds. Some lines were short, measuring about 2.3 inches across; others were four times longer. The pigeons were trained to evaluate either the length of the line or how long it was displayed. They found that the more time a line was displayed, the longer in length the pigeon judged it to be. The reverse was true too: If the pigeons encountered a longer line, they thought it existed in time for a greater duration. Pigeons, the scientists concluded, understand the concepts of both time and space; the researchers noted "similar results have been found with humans and other primates."

It's thought that humans process those concepts with a brain region called the parietal cortex; pigeon brains lack that cortex, so they must have a different way of judging space and time.

4. THEY CAN FIND THEIR WAY BACK TO THE NEST FROM 1300 MILES AWAY.

A pigeon flying in front of trees.
iStock

The birds can do this even if they've been transported in isolation—with no visual, olfactory, or magnetic clues—while scientists rotate their cages so they don't know what direction they're traveling in. How they do this is a mystery, but people have been exploiting the pigeon's navigational skills since at least 3000 BCE, when ancient peoples would set caged pigeons free and follow them to nearby land.

Their navigational skills also make pigeons great long-distance messengers. Sports fans in ancient Greece are said to have used trained pigeons to carry the results of the Ancient Olympics. Further east, Genghis Khan stayed in touch with his allies and enemies alike through a pigeon-based postal network.

5. THEY SAVED THOUSANDS OF HUMAN LIVES DURING WORLD WARS I AND II.

Pigeons' homing talents continued to shape history during the 20th century. In both World Wars, rival nations had huge flocks of pigeon messengers. (America alone had 200,000 at its disposal in WWII.) By delivering critical updates, the avians saved thousands of human lives. One racing bird named Cher Ami completed a mission that led to the rescue of 194 stranded U.S. soldiers on October 4, 1918.

6. TWO PIGEONS ALMOST DISTRACTED FROM THE DISCOVERY OF EVIDENCE OF THE BIG BANG.

In 1964, scientists in Holmdel, New Jersey, heard hissing noises from their antenna that would later prove to be signals from the Big Bang. But when they first heard the sound, they thought it might be, among other things, the poop of two pigeons that were living in the antenna. "We took the pigeons, put them in a box, and mailed them as far away as we could in the company mail to a guy who fancied pigeons," one of the scientists later recalled. "He looked at them and said these are junk pigeons and let them go and before long they were right back." But the scientists were able to clean out the antenna and determine that they had not been the cause of the noise. The trap used to catch the birds (before they had to later be, uh, permanently removed) is on view at the Smithsonian Air & Space Museum.

7. YOU CAN TRAIN THEM TO BE ART SNOBS …

Japanese psychologist Shigeru Watanabe and two colleagues earned an Ig Nobel Prize in 1995 for training pigeons, in a lab setting, to recognize the paintings of Claude Monet and Pablo Picasso and to distinguish between the painters. The pigeons were even able to use their knowledge of impressionism and cubism to identify paintings of other artists in those movements. Later, Watanabe taught other pigeons to distinguish watercolor images from pastels. And in a 2009 experiment, captive pigeons he'd borrowed were shown almost two dozen paintings made by students at a Tokyo elementary school, and were taught which ones were considered "good" and which ones were considered "bad." He then presented them with 10 new paintings and the avian critics managed to correctly guess which ones had earned bad grades from the school's teacher and a panel of adults. Watanabe's findings indicate that wild pigeons naturally categorize things on the basis of color, texture, and general appearance.

8. … AND TO DISTINGUISH WRITTEN WORDS.

In a 2016 study, scientists showed that pigeons can differentiate between strings of letters and actual words. Four of the birds built up a vocabulary of between 26 and 58 written English words, and though the birds couldn't actually read them, they could identify visual patterns and therefore tell them apart. The birds could even identify words they hadn't seen before.

9. FLUFFY PIGEON FEET MIGHT ACTUALLY BE PARTIAL WINGS.

A white pigeon with curly feathers and fluffy feet.
iStock

A few pigeon breeds have fuzzy legs—which hobbyists call "muffs"—rather than scaly ones. According to a 2016 study, the DNA of these fluffy-footed pigeons leads their hind legs to take on some forelimb characteristics, making muffed pigeon legs look distinctly wing-like; they're also big-boned. Not only do they have feathers, but the hindlimbs are somewhat big-boned, too. According to biologist Mike Shapiro, who led the study, "pigeons' fancy feathered feet are partially wings."

10. SOME PIGEONS DISTRACT FALCONS WITH WHITE RUMP FEATHERS.

In a life-or-death situation, a pigeon's survival could depend upon its color pattern: Research has shown that wild falcons rarely go after pigeons that have a white patch of feathers just above the tail, and when the predators do target these birds, the attacks are rarely successful.

To figure out why this is, Ph.D. student Alberto Palleroni and a team tagged 5235 pigeons in the vicinity of Davis, California. Then, they monitored 1485 falcon-on-pigeon attacks over a seven-year span. The researchers found that although white-rumped pigeons comprised 20 to 25 percent of the area's pigeon population, they represented less than 2 percent of all the observed pigeons that were killed by falcons; the vast majority of the victims had blue rumps. Palleroni and his team rounded up 756 white- and blue-rumped pigeons and swapped their rump feathers by clipping and pasting white feathers on blue rumps, and vice versa. The falcons had a much easier time spotting and catching the newly blue-rumped pigeons, while the pigeons that received the white feathers saw predation rates plummet.

Close observation revealed that the white patches distract birds of prey. In the wild, falcons dive-bomb other winged animals from above at high speeds. Some pigeons respond by rolling away in midair, and on a spiraling bird, white rump feathers can be eye-catching, which means that a patch of them may divert a hungry raptor's focus long enough to make the carnivore miscalculate and zip right past its intended victim.

11. DODOS WERE RELATED TO TODAY'S PIGEONS.

Two blue and green Nicobar pigeons.
iStock

Though most of this list focuses on the rock pigeon, there are 308 living species of pigeons and doves. Together, they make up an order of birds known as the columbiformes. The extinct dodo belonged to this group as well.

Flightless and (somewhat) docile, dodos once inhabited Mauritius, an island near Madagascar. The species had no natural predators, but when human sailors arrived with rats, dogs, cats, and pigs, it began to die out, and before the 17th century came to a close, the dodo had vanished altogether. DNA testing has confirmed that pigeons are closely related to the dodo, and the vibrant Nicobar pigeon (above) is its nearest genetic relative. A multi-colored bird with iridescent feathers, this near-threatened creature is found on small islands in the South Pacific and off Asia. Unlike the dodo, it can fly.

12. AT ONE POINT, MORE THAN ONE-QUARTER OF ALL THE BIRDS LIVING IN THE U.S. MAY HAVE BEEN PASSENGER PIGEONS.

Wild/feral rock pigeons reside in all 50 states, which makes it easy to forget that they're invasive birds. Originally native to Eurasia and northern Africa, the species was (most likely) introduced to North America by French settlers in 1606. At the time, a different kind of columbiform—this one indigenous—was already thriving there: the passenger pigeon (Ectopistes migratorius). As many as 5 billion of them were living in America when England, Spain, and France first started colonizing, and they may have once represented anywhere from 25 to 40 percent of the total U.S. bird population. But by the early 20th century, they had become a rare sight, thanks to overhunting, habitat loss, and a possible genetic diversity issue. The last known passenger pigeon—a captive female named Martha—died on September 1, 1914.

13. THEY'RE REALLY GOOD AT MULTITASKING.

According to one study, they're more efficient multitaskers than people are. Scientists at Ruhr-Universitat Bochum put together a test group of 15 humans and 12 pigeons and trained all of them to complete two simple jobs (like pressing a keyboard once a light bulb came on). They were also put in situations wherein they'd need to stop working on one job and switch over to another. In some trials, the participants had to make the change immediately. During these test runs, humans and pigeons switched between jobs at the same speed.

But in other trials, the test subjects were allowed to complete one assignment and then had to wait 300 milliseconds before moving on to the next job. Interestingly, in these runs, the pigeons were quicker to get started on that second task after the period ended. In the avian brain, nerve cells are more densely packed, which might enable our feathered friends to process information faster than we can under the right circumstances.

14. PIGEONS PRODUCE FAKE "MILK."

Only mammals produce genuine milk, but pigeons and doves (along with some other species of birds) feed their young with something similar—a whitish liquid filled with nutrients, fats, antioxidants, and healthy proteins called "crop milk." Both male and female pigeons create the milk in the crop, a section of the esophagus designed to store food temporarily. As is the case with mammal milk, the creation of crop milk is regulated by the hormone prolactin. Newly-hatched pigeons drink crop milk until they're weaned off it after four weeks or so. (And if you've ever asked yourself, "Where are all the baby pigeons?" we have the answer for you right here.)

15. ONE STUDY SUGGESTS THAT, GIVEN THE RIGHT CONDITIONS, THEY'RE AS GOOD AT IDENTIFYING CANCER AS DOCTORS.

We've already established that pigeons are excellent at differentiating between artists and words, but a 2015 study revealed they can also distinguish between malignant and benign growths in the right conditions. Researchers at University of California Davis Medical Center put 16 pigeons in a room with magnified biopsies of potential breast cancers. If the pigeons correctly identified them as either benign or malignant, they got a treat, According to Scientific American.

"Once trained, the pigeons' average diagnostic accuracy reached an impressive 85 percent. But when a "flock sourcing" approach was taken, in which the most common answer among all subjects was used, group accuracy climbed to a staggering 99 percent, or what would be expected from a pathologist. The pigeons were also able to apply their knowledge to novel images, showing the findings weren't simply a result of rote memorization."

Mammograms proved to be more of a challenge, however; the birds could memorize signs of cancer in the images they were trained on but could not identify the signs in new images.

No matter how impressive their results, "I don't anticipate that pigeons, no matter how good they become at pathology or radiology, will be playing a role in actual patient care—certainly for the foreseeable future," study co-author Richard M. Levenson told Scientific American. "There are just too many regulatory barriers—at least in the West."

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