10 Juicy Facts About Leeches

Ian Cook
Ian Cook

Leeches get a bad rap, but they’re actually pretty cool once you get to know them—and we're finding out more about them, even today. Recently, a team led by Anna Phillips, curator of parasitic worms at the Smithsonian National Museum of Natural History, discovered a new species of medicinal leech (pictured above) in a Maryland swamp. We asked parasite expert and curator at the American Museum of Natural History Mark E. Siddall to share some surprising facts about the worms we love to hate. 

1. Not all leeches suck blood.

Hematophagous, or blood-feeding, species are only one type of leech. “The vast majority of species are [hematophagous],” Siddall tells Mental Floss, “but it depends on the environment. In North America, there are probably more freshwater leeches that don’t feed on blood than there are blood-feeders.” And even among the hematophagous species, there are not too many who are after you. “Very few of them are interested in feeding on human blood,” Siddall says. “Certainly they’ll do it, if they’re given the opportunity, but they’re not what they’re spending most of their time feeding on.” 

2. Leeches are everywhere.

Japanese leech on a log
Pieria, Wikimedia Commons // Public Domain

“Every continent on the planet has leeches, with the exception of Antarctica,” Siddall says. “And even then there are marine leeches in Antarctic waters.” Humans have co-existed with leeches for so long, according to Siddall, that just about every language has a word for leech. 

3. Leeches have made a comeback in medicine.

Bloodletting for bloodletting’s sake has fallen out of favor with Western physicians, but that doesn’t mean medicinal leeches are enjoying a cushy retirement. Today, surgeons keep them on hand in the operating room and use them as mini-vacuums to clean up blood. “That is a perfectly sensible use of leeches,” Siddall says. Other uses, though, are less sensible: “The more naturopathic application of leeches in order to get rid of bad blood or to cure, I don’t know, whatever happens to ail you, is complete hooey,” he says. How on Earth would leeches take away bad blood and leave good blood? It’s silly.” 

4. Novelist Amy Tan has her own species of leeches.

Land-based leeches made an appearance in Tan’s 2005 book Saving Fish from Drowning, a fact that instantly put the author in leech researchers’ good graces. “There are not a lot of novels out there with terrestrial leeches in them,” Siddall says. So when he and his colleagues identified a new species of tiny terrestrial leeches, they gave the leech Tan’s name. The author loved it. “I am thrilled to be immortalized as Chtonobdella tanae,” Tan said in a press statement. “I am now planning my trip to Queensland, Australia, where I hope to take leisurely walks through the jungle, accompanied by a dozen or so of my namesake feeding on my ankles.”

5. Leeches can get pretty big.

The giant Amazon leech (Haementeria ghilianii) can grow up to 18 inches and live up to 20 years. And yes, this one’s a blood-feeder. Like all hematophagous species, H. ghilianii sticks its proboscis (which can be up to 6 inches long) into a host, drinks its fill, and falls off. Scientists thought the species was extinct until a zoologist found two specimens in the 1970s, one of whom he named Grandma Moses. We are not making this up.

6. Leeches make good bait.

Many walleye anglers swear by leeches. “A leech on any presentation moves more than other types of live bait," pro fisher Jerry Hein told Fishing League Worldwide. "I grew up fishing them, and I think they're the most effective live bait around no matter where you go." There’s an entire leech industry to provide fishers with their bait. One year, weather conditions kept the leeches from showing up in their typical habitats, which prevented their collection and sale. Speaking to CBS news, one tackle shop owner called the absence of leeches “the worst nightmare in the bait industry.”

7. Leech scientists use themselves as bait.

Siddall and his colleagues collect and study wild leeches. That means hours of trekking through leech territory, looking for specimens. “Whether we’re wandering in water or traipsing through a bamboo forest,” Siddall says, “we are relying on the fact that leeches are attracted to us.” Do the leeches feed on them? “Oh my god, yes. We try to get them before they feed on us … but sometimes, obviously, you can’t help it.”

8. Leech sex is mesmerizing.

Like many worms, leeches are all hermaphroditic. The specifics of mating vary by species, but most twine themselves together and trade sperm packets. (The two leeches in the video above are both named Norbert.)

9. Some leech species make surprisingly caring parents. 

“There’s a whole family of leeches that, when they lay their eggs, will cover them with their own bodies,” Siddall says. “They’ll lay the eggs, cover them with their bodies, and fan the eggs to prevent fungus or bacteria from getting on them, and then when the eggs hatch, they will attach to the parent. They’re not feeding on the parent, just hanging on, and then when the parent leech goes to its next blood meal it’s carrying its offspring to its next blood meal. That’s pretty profound parental care, especially for invertebrates.”

10. You might be the next to discover a new leech species. 

Despite living side-by-side with leeches for thousands of years, we’ve still got a lot to learn about them. Scientists are aware of about 700 different species, but they know there are many more out there. “I’ll tell you what I wish for,” Siddall says. “If you ever get fed on by a leech, rather than tearing off and burning it and throwing it in the trash, maybe observe it and see if you can see any color patterns. Understand that there’s a real possibility that it could be a new species. So watch them, let them finish. They’re not gonna take much blood. And who knows? It could be scientifically useful.”

10 Terrifyingly Huge Birds You Should Know

AndreaWillmore/iStock via Getty Images
AndreaWillmore/iStock via Getty Images

They’re gigantic, they’re often defensive, and you wouldn’t want to run into them in a zoo after hours. Meet a few of the world’s biggest birds with attitude, from flightless giants to modern-day pterodactyls.

1. Ostrich

Everyone knows that the ostrich is the world’s biggest bird, weighing an average of 230 pounds and standing 7 feet tall (and some individuals can grow up to 9 feet). They can also chase you down: Ostriches are the fastest species on two legs, with a top speed of about 43 mph. They can maintain a swift 30 mph pace for 10 miles, making them the marathon champs of the avian world.

2. Southern Cassowary

Often called the most dangerous bird on Earth, in addition to being one of the planet’s biggest birds, the southern cassowary is roughly 150 pounds of mean. On each foot is a 5-inch claw that cassowaries use to defend themselves. At least two people have been kicked to death by cassowaries, the most recent being a Florida man who unwisely kept one of the birds as a pet.

3. Emu

Emu with eggs
JohnCarnemolla/iStock via Getty Images

Like a smaller, shaggier ostrich, the 5- to 6-foot emu is the second-largest bird on Earth (as well as a goofy spokesbird for insurance). During the breeding season, female emus fight enthusiastically over unattached males. But the results of this mating ritual are impressive: clutches of forest-green, oval eggs that resemble giant avocados.

4. Greater Rhea

This flightless bird is named for the Titan goddess Rhea, who gave birth to all of the Olympian gods and goddesses in Greek mythology. At up to 5 feet tall and 66 pounds, the greater rhea may not seem like as much of a terror as the ostrich. But it gathers in massive flocks of up to 100 birds during the non-breeding season, so watch out if you happen to be in its South American habitat.

5. Dalmatian Pelican

Dalmatian pelicans
musicinside/iStock via Getty Images

How scary can a pelican be, you ask? When it stands almost 6 feet tall, weighs 33 pounds, and has a wingspan of 9 feet—all traits of the Dalmatian pelican—it's pretty petrifying. These scruffy-feathered monsters, native to Europe and Asia, breed in colonies of up to 250 pairs and can gulp impressive mouthfuls of fish in one go.

6. Mute Swan

One of the heaviest flying birds, mute swans look harmless as they glide over ponds, lakes, and rivers. But mute swans are far from silent when defending their families and territory. Male swans warn interlopers that they’re getting too close with a hiss, then can launch a straight-up assault, bashing the intruder with their wings. They’ll even attack kayakers, canoeists, and people just minding their own business.

7. Andean Condor

Andean condor
Donyanedomam/iStock via Getty Images

This freakishly big vulture isn’t satisfied with just any carrion—it prefers large carcasses like cattle and deer for dinner. Maintaining its average weight of 25 pounds requires a lot of calories, after all. Its wingspan is slightly less than its northern cousin, the California condor, but it still reaches a dramatic 9 to 10 feet.

8. Cinereous Vulture

Another big bird with a 10-foot wingspan, this Old World vulture has excellent vision to spot carrion while it flies, and a featherless head that resists the accumulation of gore when it feeds. Though it’s intimidating to look at, the cinereous vulture plays an important role in its ecosystem by cleaning up roadkill and other dead animals.

9. Marabou Stork

Marabou stork
Sander Meertins/iStock via Getty Images

As if its red-tinged wattle, black back, and dagger-esque bill weren’t alarming enough, the marabou stork is sometimes called the “undertaker bird” thanks to its Dracula-like appearance. It also eats other birds. The largest verified wingspan on a marabou stork measured 10.5 feet, though unverified reports cited a specimen with 13.3-foot span.

10. Shoebill

Shoebill storks may not be the tallest, heaviest, or widest-winged birds, but just look at that death stare. On top of having a nutcracker for a face, the 5-foot-tall shoebill leads a fearsome lifestyle. It stands absolutely still for hours to hunt prey, watching for lungfish or baby crocodiles, then spreads its wings and collapses over it while trapping the target in its bill.

Scientists Capture Video of Deepstaria, a Rarely Seen, Shapeshifting Jellyfish

OET/NautilusLive
OET/NautilusLive

Millions of years of evolution taking place beneath the sea's surface have produced some bizarre animals. Jellyfish are among the oldest—and strangest—of the bunch. Some have "transient" anuses that only form when necessary, and others can renew their life cycles indefinitely. Little is known about Deepstaria, a jellyfish recently spotted by the crew of the Nautilus research vessel in the central Pacific Ocean, but as the video below shows, it's no less unusual than other species of jellyfish.

As Live Science reports, scientists aboard the Nautilus were scanning the seafloor about halfway between the U.S. and Australia when they spotted a spooky-looking creature hovering in front of them. It soon became clear that cosplaying a ghost wasn't all it could do. The jelly unfurled its sheet-like bell to reveal a geometric mesh membrane used to distribute nutrients throughout its body—a telltale sign of Deepstaria. It spends the rest of the video putting on a show for its guests, transforming from something resembling a crumpled plastic bag to a billowing blanket shape.

Deepstaria enigmatica was discovered by the Jacques Cousteau-designed Deepstar 4000 submersible—the vessel the species is named after—in the 1960s. It's only been spotted about a dozen times in the years since, and many details of how it lives remain a mystery to researchers.

Deepstaria's most distinctive feature is its massive, flowing bell. It lacks the tentacles most jellyfish use to wrangle prey, and scientists suspect it instead uses its bell as a net when hunting. The specimen captured in this video appears to be harboring a stowaway: a bright-red, living isopod suspended inside the bell. It isn't clear if the creature hitched a ride on purpose to evade more ferocious predators, if it's some type of parasite, or if it's the jellyfish's lunch.

With so many undiscovered and understudied species living in the sea, the Nautilus research vessel is frequently stumbling upon extraordinary examples of ocean life. In 2016 alone, it recorded footage of a googly-eyed stubby squid and a mysterious purple orb.

[h/t Live Science]

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