CLOSE
istock
istock

20 Things You Didn’t Know About Sea Turtles

istock
istock

Sea turtles live in waters all around the world, except for the planet’s extreme north and south regions, and live as long as 80 years. There are seven species of sea turtles, and six of them—green, hawksbill, Kemp’s ridley, leatherback, loggerhead, and olive ridley—are on the U.S. Endangered Species list. The flatback, found only in the area around Australia, is considered vulnerable by that country. Here are 20 other things you might not know about sea turtles.

1. Hawksbills Are Named for their jaws

Hawksbill sea turtles have raptorlike jaws to reach hard to get to places in coral reefs. Their favorite food is sponges. 

2. Greens go for greens

Adult greens are the only herbivorous sea turtles, eating seagrass and algae.

3. Leatherbacks are adapted for eating soft stuff

Leatherbacks eat jellyfish and other soft-bodied animals and have stiff spines in their throats to help them swallow this slippery prey.

4. Olive Ridleys have Mass nesting parties

Olive ridley sea turtles practice nesting in large groups, known as arribadas. While solitary nesting has been documented in as many as 40 countries, this spectacular event is seen in only five: Mexico, Nicaragua, Costa Rica, Panama, and India. Arribadas can include as many as 200,000 individuals. 

5. Nest Temperatures Determines the Sex of Turtle Hatchlings

Warmer temperatures mean more females, cooler ones more males. (Too-high temps kill the eggs.) In a study published in Nature, scientists estimated that "that light-coloured beaches currently produce 70.10 percent females whereas dark-coloured beaches produce 93.46 percent females."

6. A home movie solved a nesting mystery

For decades, scientists had no idea where Kemp's ridley sea turtles nested. Then, at the 1961 meeting of the American Society of Ichthyologists and Herpetologists in Austin, Texas, biologists saw a home movie made in 1947 by Andres Herrera. It showed at least 40,000 ridleys nesting on a beach on the northern Gulf coast of Mexico. 

7. Kemp's Ridley's are now making their home in Texas

In order to increase their population, a secondary nesting location was created for Kemp's ridley sea turtles on Texas's Padre Island National Seashore. Over 20,000 eggs were transferred from Mexico and released in Texas. In 1996 there were 369 hatchlings released; by 2013 that number grew to 11,369.

8. Kemp's Ridley Turtles Suffered in the Deepwater Horizon Oil Spill

According to presentation at the Second International Kemp’s Ridley Sea Turtle Symposium in Texas in November, recent studies indicate that the number of Kemp's ridley sea turtles at the site of the Deepwater Horizon oil spill were considerably higher than previously thought, and some scientists are concerned the Texas nesting population will suffer because of it.

9. One bycatch problem is mostly solved

Sea turtle mortality in shrimp trawls was once a major problem in the Gulf of Mexico, but the introduction of Turtle Excluder Devices (TEDs) on trawl nets starting 20 years ago has drastically reduced the number of sea turtles killed.

10. They can dive very deep, and stay under for long periods.

As reptiles, sea turtles breathe air, but they have the ability to remain submerged for hours at a time. Leatherback sea turtles can dive up to 3000 feet deep. 

11. They're Long-distance swimmers

Sea turtles have been documented migrating vast distances. One was tracked traveling more than 9000 miles from Baja California to Japan. 

12. One scientist uses her dog to sniff out clandestine nests

While most sea turtle species nest at night, the Kemp’s ridley nests during the day, when winds quickly blow away the female’s tracks. This can make it difficult for Padre Island National Seashore staff to find nests so they can bring the eggs into a special lab to incubate. Donna Shaver, PhD, chief of the division of sea turtle science and recovery at the Seashore, trained her Cairn terrier, Ridley, to sniff out nests.

13. To track hatchlings, scientists use manicure supplies

Scientists don’t know much about the early stages of sea turtle life. Given a hatchling’s small size and rapid growth, the usual ways of attaching tracking tags don’t work. But researchers found that a neoprene-silicone attachment on an acrylic base-coat—just like that used for fake fingernails—kept tags on for an average of 70 days, long enough to clear up a lot of the mystery of those lost years. [PDF]

14. Scientists pulled off a great egg evacuation

After the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, scientists were concerned that sea turtles hatching on the Gulf beaches of Alabama and northern Florida would swim out into deadly oil. They launched a massive relocation effort, moving 28,000 eggs between June 25 and August 18 to Kennedy Space Center on Florida's east coast. (The eggs were shipped via FedEx.) The rescue succeeded; in July, August and September, 14,000 hatchlings—mostly loggerheads—were released into the Atlantic Ocean.

15. Sea turtles are still threatened by poaching

Poaching remains a significant threat to sea turtles around the world. For example, in November, authorities in Vietnam seized more than 1000 preserved sea turtle carcasses from a warehouse. Many of them contain tracking chips implanted by researchers. 

16. Turtles get tumors

Fibropapillomatosis is a chronic and often lethal tumor-forming disease in sea turtles. Recent research suggests that FP occurs more frequently in green sea turtles that forage in waters subject to eutrophication , or an increase in organic matter that leads to algal blooms. Stormwater run-off and other human activities contribute to eutrophication. 

17. They eat a lot of plastic.

Plastic debris in the ocean represents a significant threat to sea turtles, with a recent study showing that leatherback and green sea turtles are at the greatest risk of becoming sick or dying from eating plastic. A 1993 study found plastic debris in the digestive tracts of 51 percent of loggerheads and necropsies of dead turtles have found some with their entire digestive tracts packed with pieces of plastic bags. 

18. Another bycatch problem might be solved

Small-scale coastal gillnet fisheries, common in many countries, accidentally catch significant numbers of sea turtles, injuring or drowning them. But changing the type of bait or using ultraviolet (UV) light-emitting diodes can reduce the chances of capture, according to a recent study. 

19. Volunteers help save them

Sea turtle conservation projects around the world rely on volunteers to help patrol nesting beaches, move eggs into protected corrals, and monitor the release of hatchlings. Volunteers generally commit for at least two weeks, stay in tents or cabins, and enjoy communal meals. 

20. Turtles have a compass in the brain

A female sea turtles returns to the beach where she hatched when it is time to lay her own eggs. Some species travel vast distances in the 10 to 20 years between hatching and first nest. Scientists generated magnetic fields in the lab and demonstrated that sea turtles have the ability to detect the Earth's magnetic field and use it as an orientation cue.

All images courtesy of iStock unless otherwise noted. 

nextArticle.image_alt|e
Scientific Reports, Fernando Ramirez Rozzi
arrow
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.

nextArticle.image_alt|e
iStock
arrow
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."

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios