10 Eye-Popping Facts About Mantis Shrimp

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"Beautiful" and "deadly" are two descriptors you don’t typically see attached to shrimp. But the mantis shrimp is in a class of its own. This colorful specimen has earned a reputation for being one of the most fearsome creatures of the deep. Here are 10 facts worth knowing about the pint-sized bruisers.

1. THEY’RE NOT SHRIMP.

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Despite their namesake and relatively puny stature, mantis shrimp aren’t shrimp at all. (Neither, of course, are they mantises.) They're stomatopods, distant relatives to crabs, shrimp, and lobsters.

2. THEY PACK A POWERFUL PUNCH.

The peacock mantis shrimp (Odontodactylus scyllarus) uses two appendages called dactyl clubs to pummel its prey like aquatic Rock 'Em Sock 'Em Robots—that is, if kids’ toys could punch fast enough to boil water and split fingers to the bone. These wrecking ball "fists" spring forth from their bodies at 50 mph, accelerating quicker than a .22-caliber bullet. At those speeds, the water surrounding them briefly reaches the temperature of the Sun’s surface. When the dactyl clubs hit their target, they deliver 160 pounds of force, smashing through shells like a lightning-fast crab mallet.

3. THERE ARE HUNDREDS OF SPECIES.

Mantis shrimp come in a variety of species, and we’re aware of about 550 of them. Stomatopods from different species range in size from smaller than an inch to longer than a foot. They’re usually classified by murder method—either smashing, as detailed above, or spearing. In place of dactyl clubs, spearers have two sharp appendages on the front of their bodies built for harpooning prey. Spear-wielding mantis shrimp don’t move as fast as their club-fisted counterparts (their strikes are about 10 times slower), but the threat of death by impalement is intimidating on its own.

4. THEIR VISION IS UNPARALLELED.

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Peacock mantis shrimp have the most complex set of peepers in the animal kingdom. Each eye contains 12 photoreceptors that allow them to sense different types of color. For comparison, human eyes typically contain three types of light-sensitive cells for seeing red, blue, and green. This has led some to conclude that mantis shrimp perceive the world in a psychedelic rainbow of vibrant color we can’t begin to comprehend. But in reality, the crustaceans are actually worse at differentiating between subtle variations in hue than we are.

A study from the University of Queensland found that when mantis shrimp were shown colors with a difference in wavelength less than 25 nanometers, they had trouble telling them apart. But just because mantis shrimp may not see the variations between powder blue and periwinkle doesn’t mean their vision isn’t extraordinary. On the contrary, their optic abilities are on a completely separate level from ours, functioning more like a satellite than anything found in nature. Scientists believe that mantis shrimp take all the visual information they see into their brains at once without processing it, allowing them to react to their surroundings as quickly as possible. Their independently roaming eyes and trinocular vision also make them excellent hunters.

5. THEY SHARE A SECRET LANGUAGE.

Roy Caldwell, University Of California, Berkeley

 
In addition to the all epic abilities listed above, mantis shrimp are one of the only creatures capable of seeing polarized light. This has allowed them to develop a secret code that’s undetectable to other species. The Haptosquilla trispinosa species of mantis shrimp wields feathery feeding appendages called maxillipeds that are marked with iridescent, blue spots. The cells of these features reflect light in a unique way. Instead of bouncing light into a reflective structure like the polarizing cells developed by humans, the cells distribute light across the spot’s surface. The brilliant light is plainly visible to other mantis shrimp, allowing them to signal members of their species while staying hidden from predators.

6. YOU WON’T FIND THEM IN MOST AQUARIUMS.

Prilfish via Flickr // CC BY 2.0

You’d think a mantis shrimp’s technicolor exterior would make it a staple at most aquariums, but this creature is rarely kept in captivity. The same dactyl clubs that allow them to shatter shellfish are also capable of cracking a glass tank. When aquariums do accept a ruthless specimen into their collection, it must kept behind shatterproof acrylic glass. On top of that, a captive mantis shrimp needs to be the sole occupant of its specially constructed home, lest it decides to treat its tank-mates as punching bags.

7. THEY MAKE MENACING SOUNDS.

Elias Levy via Flickr // CC BY 2.0

It’s only natural that a creature as ferocious as the stomatopod would have a threatening call to match. California mantis shrimp have been known to make low, rumbling growling sounds both in the wild and the lab. Male mantis shrimp often emit grunts at dawn and dusk, the periods of the day when they’re most likely to be hunting for food or guarding their homes. Scientists theorize that the growls are meant to attract mates and ward off competitors.

8. THEY’RE HELPING SCIENTISTS BUILD BETTER BODY ARMOR.

Jens Petersen via Wikimedia Commons // CC-BY-SA-3.0

 
The mantis shrimp’s super-powered punching abilities raise a puzzling question: How can the animal deliver such a deadly blow without injuring itself? To get to the bottom of the mystery, researchers looked at the composition of the peacock mantis shrimp’s built-in weaponry. They found that the creature’s dactyl clubs consisted of an outer coating of hydroxyapatite, a hard crystalline calcium-phosphate ceramic material. Beneath the surface lies the key to the animal’s anti-fracturing qualities. Layers of elastic polysaccharide chitin underlying the shell are positioned in a way to act as shock absorbers, reducing the possibility of cracks. The design is so effective that researchers modeled a new type of carbon fiber material after it with potential applications in aircraft panels and military body armor.

9. THEY PRACTICE SOCIAL MONOGAMY.

Barry Peters via Wikimedia Commons // CC BY 2.0

The life of a mantis shrimp isn’t all cold-blooded killing. Some species of stomatopods are known to engage in the rare practice of social monogamy, a behavior that’s especially remarkable among crustaceans. This means mantis shrimp will choose one partner to share food, shelter, and raise offspring with over the course of a lifetime. What may sound romantic to humans serves a practical purpose for mantis shrimp. Research has shown that certain mantis shrimp tend to cluster outside reefs instead of living in the heart of the action. Without the need to go looking for someone new to mate with on a regular basis, mantis shrimp couples are able to enjoy a relatively safe, sedentary lifestyle secluded from predators.

10. THEY’RE OLDER THAN DINOSAURS.

Derek Keats via Flickr // CC BY 2.0

Stomatopods began evolving independently from other crustaceans nearly 400 million years ago, about 170 million years before the first dinosaurs appeared on the scene. Since then they’ve followed an isolated, evolutionary lineage that’s resulted in some of their more unique characteristics. Their biology is so bizarre that scientists have assigned them the nickname "shrimp from Mars."

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13 Incredible Facts About Frederick Douglass

Photo Illustration: Mental Floss. Douglass: Glasshouse Images, Alamy. Backgrounds: iStock
Photo Illustration: Mental Floss. Douglass: Glasshouse Images, Alamy. Backgrounds: iStock

The list of Frederick Douglass's accomplishments is astonishing—respected orator, famous writer, abolitionist, civil rights leader, presidential consultant—even more so when you consider that he was a former slave with no formal education. In honor of his 201st birthday, here are 13 incredible facts about the life of Frederick Douglass.

1. He bartered bread for knowledge.

Because Douglass was a slave, he wasn't allowed to learn to read or write. A wife of a Baltimore slave owner did teach him the alphabet when he was around 12, but she stopped after her husband interfered. Young Douglass took matters into his own hands, cleverly fitting in a reading lesson whenever he was on the street running errands for his owner. As he detailed in his autobiography, Narrative of the Life of Frederick Douglass, he'd carry a book with him while out and about and trade small pieces of bread to the white kids in his neighborhood, asking them to help him learn to read the book in exchange.

2. He credited a schoolbook with shaping his views on human rights.

Engraving of Frederick Douglass, circa the 1850s.
Engraving of Frederick Douglass, circa the 1850s.
Hulton Archive, Getty Images

During his youth, Douglass obtained a copy of The Columbian Orator, a collection of essays, dialogues, and speeches on a range of subjects, including slavery. Published in 1797, the Orator was required reading for most schoolchildren in the 1800s and featured 84 selections from authors like Cicero and Milton. Abraham Lincoln was also influenced by the collection when he was first starting in politics.

3. He taught other slaves to read.

While he was hired out to a farmer named William Freeland, a teenaged Douglass taught fellow slaves to read the New Testament—but a mob of locals soon broke up the classes. Undeterred, Douglas began the classes again, sometimes teaching as many as 40 people.

4. His first wife helped him escape from slavery.

Portrait of Anna Murray Douglass, Frederick Douglass's first wife.
First published in Rosetta Douglass Sprague's book My Mother As I Recall Her, Wikimedia Commons // Public Domain

Anna Murray was an independent laundress in Baltimore and met Douglass at some point in the mid-1830s. Together they hatched a plan, and one night in 1838, Douglass took a northbound train clothed in a sailor's uniform procured by Anna, with money from her savings in his pocket alongside papers from a sailor friend. About 24 hours later, he arrived in Manhattan a free man. Anna soon joined him, and they married on September 15, 1838.

5. He called out his former owner.

In an 1848 open letter in the newspaper he owned and published, The North Star, Douglass wrote passionately about the evils of slavery to his former owner, Thomas Auld, saying "I am your fellow man, but not your slave." He also inquired after his family members who were still enslaved a decade after his escape.

6. He took his name from a poem.

He was born Frederick Augustus Washington Bailey, but after escaping slavery, Douglass used assumed names to avoid detection. Arriving in New Bedford, Massachusetts, Douglass, then using the surname "Johnson," felt there were too many other Johnsons in the area to distinguish himself. He asked his host (ironically named Nathan Johnson) to suggest a new name, and Mr. Johnson came up with Douglas, a character in Sir Walter Scott's poem The Lady of the Lake.

7. He was deemed the 19th century's most photographed American.

Portrait of Frederick Douglass
Wikimedia Commons // Public Domain

There are 160 separate portraits of Douglass, more than Abraham Lincoln or Walt Whitman, two other heroes of the 19th century. Douglass wrote extensively on the subject during the Civil War, calling photography a "democratic art" that could finally represent black people as humans rather than "things." He gave his portraits away at talks and lectures, hoping his image could change the common perceptions of black men.

8. He refused to celebrate Independence Day.

Douglass was well-known as a powerful orator, and his July 5, 1852 speech to a group of hundreds of abolitionists in Rochester, New York, is considered a masterwork. Entitled "What to the Slave is the Fourth of July," the speech ridiculed the audience for inviting a former slave to speak at a celebration of the country who enslaved him. "This Fourth [of] July is yours, not mine," he famously said to those in attendance. "Do you mean, citizens, to mock me, by asking me to speak to-day?" Douglass refused to celebrate the holiday until all slaves were emancipated and laws like the Compromise of 1850, which required citizens (including northerners) to return runaway slaves to their owners, were negated.

9. He recruited black soldiers for the Civil War.

The Union attack on Fort Wagner, Charleston, during the American Civil War. The fort was under attack from July 18 to September 7, 1863, by soldiers including the 54th Massachusetts Volunteer Infantry, the first African-American regiment in the U.S. Army.
The Union attack on Fort Wagner, Charleston, during the American Civil War. The fort was under attack from July 18 to September 7, 1863, by soldiers including the 54th Massachusetts Volunteer Infantry, the first African-American regiment in the U.S. Army.
Hulton Archive, Getty Images

Douglass was a famous abolitionist by the time the war began in 1861. He actively petitioned President Lincoln to allow black troops in the Union army, writing in his newspaper: "Let the slaves and free colored people be called into service, and formed into a liberating army, to march into the South and raise the banner of Emancipation among the slaves." After Lincoln signed the Emancipation Proclamation, Douglass worked tirelessly to enlist black soldiers, and two of his sons would join the 54th Massachusetts Regiment, famous for its contributions in the brutal battle of Fort Wagner.

10. He served under five presidents.

Later in life, Douglass became more of a statesman, serving in highly appointed federal positions, including U.S. Marshal for D.C., Recorder of Deeds for D.C., and Minister Resident and Consul General to Haiti. Rutherford B. Hayes was the first to appoint Douglass to a position in 1877, and Presidents Garfield, Arthur, Cleveland, and Benjamin Harrison each sought his counsel in various positions as well.

11. He was nominated for Vice President of the United States.

As part of the Equal Rights Party ticket in 1872, Douglass was nominated as a VP candidate, with Victoria Woodhull as the Presidential candidate. (Woodhull was the first-ever female presidential candidate, which is why Hillary Clinton was called "the first female presidential candidate from a major party" during the 2016 election.) However, the nomination was made without his consent, and Douglass never acknowledged it (and Woodhull's candidacy itself is controversial because she wouldn't have been old enough to be president on Inauguration Day). Also, though he was never a presidential candidate, he did receive one vote at each of two nomination conventions.

12. His second marriage caused controversy.

Frederick Douglass with Helen Pitts Douglass (seated, right) and her sister Eva Pitts (standing, center), circa the 1880s.
Frederick Douglass with Helen Pitts Douglass (seated, right) and her sister Eva Pitts (standing, center), circa the 1880s.

Two years after his first wife, Anna, died of a stroke in 1882, Douglass married Helen Pitts, a white abolitionist and feminist who was 20 years younger than him. Even though she was the daughter of an abolitionist, Pitts's family (which had ancestral ties directly to the Mayflower) disapproved and disowned her—showing just how taboo interracial marriage was at the time. The black community also questioned why their most prominent spokesperson chose to marry a white woman, regardless of her politics. But despite the public's and their families' reaction, the Douglasses had a happy marriage and were together until his death in 1895 of a heart attack.

13. After early success, his Narrative went out of print.

Narrative of the Life of Frederick Douglass, An American Slave, Written by Himself, his seminal autobiography, was heralded a success when it came out in 1845, with some estimating that 5000 copies sold in the first few months; the book was also popular in Ireland and Britain. But post-Civil War, as the country moved toward reconciliation and slave narratives fell out favor, the book went out of print. The first modern publication appeared in 1960—during another important era for the fight for civil rights. It is now available for free online.

This article originally ran in 2018.

The 15 Best Documentaries on Netflix Right Now

A still from Ava DuVernay's 13th (2016)
A still from Ava DuVernay's 13th (2016)
Netflix

Truth is not only stranger than fiction, it’s frequently more entertaining. Thanks to the Netflix acquisition team, the streaming service offers hundreds of documentaries that chronicle everything from riveting tales of true crime to stories about bare-knuckle fighters and custody battles over amputated legs. To help you sort through their formidable selection, we’ve selected 15 films currently streaming that will either make your jaw drop, bring a tear to your eye, or both.

1. Finders Keepers (2015)

If an appendage is removed from your body, are you still its lawful owner? That’s the question posed by this irreverent investigation of Shannon Whisnant, a junk trader who successfully bids on a storage locker and discovers the mummified remains of a severed leg. The stump once belonged to John Wood, a man injured in a plane crash. When his leg was amputated as a result, he decided to keep it as a memento, storing it in a grill inside the locker. The argument over who has rightful possession of this fleshy trophy is at the center of the film, which sees the men try to resolve their differences in a variety of ways, including an appearance on Judge Mathis.

2. Long Shot (2017)

Juan Catalan is that most compelling of true crime clichés: an innocent man being railroaded for a murder he didn’t commit. With law enforcement dismissing his alibi, his lawyers make a last-ditch effort to prove that Catalan was at a Los Angeles Dodgers game at the time of the assault. How they do that—and which famous comic actor plays a role—is best left to discover on your own.

3. Gringo: The Dangerous Life of John McAfee (2016)

Anti-virus software tycoon John McAfee was one of the internet’s biggest success stories. Flush with money, power, and a desire to reinvent himself, McAfee relocated to Belize, where his story began to take on echoes of Marlon Brando’s Colonel Kurtz in Apocalypse Now. When all of McAfee’s whims are tended to by locals, questions over a neighbor’s murder take on sinister connotations. Michael Keaton is set to play McAfee in a feature film version.

4. Brother’s Keeper (1992)

The bonds of brotherhood are explored in this arresting feature about siblings Delbert, Roscoe, and Lyman Ward, farmers in upstate New York who close ranks when police begin to suspect one of them murdered their other brother, William.

5. Jim & Andy: The Great Beyond (2017)

When Jim Carrey stepped into the role of the late comedian Andy Kaufman for director Milos Forman’s 1999 biopic Man on the Moon, he didn’t so much imitate Kaufman as become him. That process was documented in behind-the-scenes footage that was buried in studio vaults for years and revealed here for the first time. Executives feared people would consider Carrey—who alternately charms and antagonizes people on the set by never behaving as “Jim”—as being exceptionally difficult to work with. Perhaps, but Carrey’s modern-day reflections on inhabiting the eccentric Kaufman even when the film cameras weren’t rolling are a fascinating study of both the performer’s commitment and the nature of identity.

6. Amanda Knox (2016)

College student Amanda Knox seized headlines in 2007 and beyond for being the prime suspect in the murder of fellow student and roommate Meredith Kercher while both were studying in Perugia, Italy. The competency and motives of Italian police are examined in this documentary, which features the first time Knox has spoken at length about her trials (yes, there was more than one) and struggles in a foreign justice system. Plenty of ink was spilled in the American media over her suspected guilt: Knox’s unflinching stare into the camera as she tells her side of the story will likely persuade you to think otherwise.

7. Fyre: The Greatest Party That Never Happened (2019)

Sun. Models. Booze. Would-be mogul Billy McFarland promised a lot and delivered little more than cold cheese sandwiches in his 2017 music festival debacle, which collected a small fortune in admission and ancillary profits and then wound up leaving hundreds of guests stranded on an island to fend for themselves. Pairing Netflix’s examination of the debacle and its fallout with Hulu’s Fyre Fraud makes for a fine double feature (even if you might be left with more questions than answers).

8. The Power of Grayskull: The Definitive History of He-Man and the Masters of the Universe (2017)

Toy and nostalgia fans will get a kick out of this rewind to the early 1980s, when Mattel’s He-Man dominated retail stores and syndicated television. The feature examines the toy line’s origins—which involved dueling toy designers and a failed attempt to secure a Conan license—and its later incarnation as a low-budget 1987 movie. (Yes, Dolph Lundgren makes an appearance.)

9. 13th (2016)

Director Ava DuVernay delivers a powerful (and Oscar-nominated) indictment of the U.S. justice system and takes a closer look at how incarceration and sentencing feeds into widespread inequality. Peering through DuVernay’s lens, viewers may feel the scales of justice are tipped in favor of privatized and profiteering prisons.

10. Icarus (2017)

The cat-and-mouse game between drug testing agencies and cheating athletes is put under a microscope in director Bryan Fogel’s Oscar-winning documentary, which uncovers the lengths competitors will go to in order to push past their physical limits. As Fogel digs deeper into the world of pro cycling and its high-ranking political influences, you may discover that drugs are so pervasive that athletes aren’t necessarily looking to cheat—they’re simply looking to even the playing field.

11. Senna (2010)

Sports documentaries don’t come much better than this portrait of Ayrton Senna, a Brazilian Formula One racer who became a national hero for his obsessive commitment to being the best. That passion conflicts with the inherent danger of his sport, which undergoes a technological metamorphosis in the 1980s and 1990s that threatens the safety of drivers. Those risks are on display in the film’s kinetic, heart-in-throat race sequences.

12. The Seven Five (2014)

There are bad cops, there are dirty cops, and then there’s Mike Dowd, a Brooklyn officer who used his badge to siphon money from criminals and exploit the very community he was charged with protecting. Dowd’s downfall ushered in one of the biggest police corruption scandals of the 1990s. The film features Dowd’s unabashed account of his dirty deeds.

13. Voyeur (2017)

Acclaimed journalist Gay Talese stumbles upon what he thinks is the story of a lifetime: A Colorado motel owner named Gerald Foos who modified his guest rooms so he could spy on his occupants. Not all of Foos’s recollections of his voyeur’s playground hold up to scrutiny, and the film sometimes wonders who’s really in control of the narrative—the directors, Talese, or the enigmatic Foos.

14. The Battered Bastards of Baseball (2014)

In the 1970s, Kurt Russell’s father, Bing Russell, started a rogue minor league baseball team, the Portland Mavericks. Playing without any Major League affiliation, the ragtag team barnstormed their way through several seasons, with an electric group of MLB castoffs making up the roster. It’s a fun look at a group that rivals the Bad News Bears in dropping the ball.

15. Dawg Fight (2015)

Florida native Dhafir “Dada5000” Harris tries to keep gangs and drugs from destroying his neighborhood by hosting a series of bare-knuckle fighting events in his mother’s backyard. The action is raw, but Harris’s intentions are pure. In orchestrating violence rather than letting it explode on the streets, Harris provides an outlet for young men to find some peace.

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