It has been a big year for leeches. A new species was discovered near Washington and announced in August by Anna Phillips, who may have the world’s best job title: curator of parasitic worms at the Smithsonian National Museum of Natural History.
The new leech, Macrobdella mimicus, has three jaws and 59 teeth, and is quite literally a creature of the Washington swamp: It drinks your blood and drops off when it’s full. This particular parasite is not registered as a foreign lobbyist.
And there’s more leech news: In May, a man was charged in what may be the first case of leech smuggling in Canadian history. He had flown into Toronto with almost 5,000 leeches in a grocery bag — for personal use. At least, that’s what he said.
What kind of personal use could that be? Well, leeches are good for bait, although fake ones are cheaper. There is do-it-yourself bloodletting. And you can keep them as pets. (They are not cheap, though: If you buy them online, you could pay $18 for a jumbo leech.)
Still, 5,000 is a lot of personal leeches. Suspicious officials called in Sebastian Kvist, curator of invertebrates at the Royal Ontario Museum, to identify the smuggled contraband. He said that dried leeches can be ground into a powder that is reputed in Chinese traditional medicine to have a variety of benefits. It is a leech-intensive process.
Kvist, who also helped identify Macrobdella mimicus, is a designer of a new museum exhibit called “Bloodsuckers: Legends to Leeches,” a celebration of the sucking, sipping, drinking and lapping of the blood of mammals, birds, reptiles, fish and amphibians in real life as well as the imagination.
The exhibit opens Nov. 16 at the Royal Ontario Museum, in case Halloween is just too short for you. Kvist said that although the smuggling incident did not prompt the exhibit, some of the leeches seized at the airport will be on display — live.
He and Doug Currie, senior curator of entomology at the museum, have been plotting such an exhibit for some years, because they both research blood-feeders and wanted to open up the world of hematophagy to the public.
Although insects are big in the blood-feeding world, leeches occupy a special place in the human imagination — somewhere between vampire bats and that tiny fish that was once reputed to swim up the human urethra.
To those who love them, leeches are just incredibly cool. Mark Siddall, a curator and professor at New York’s American Museum of Natural History known far and wide as “the leech guy,” bows to no one in his admiration.
Hirudin, an anticoagulant derived from leeches, was essential in early human dialysis, he pointed out. Leeches are now used in certain kinds of surgery, such as the reattachment of a body part, to drain excess blood. They have even been approved by the Food and Drug Administration as a medical device.
“They’re beautiful,” Siddall noted. If you can bear to look at the next one that gets attached to you in a pond or stream, you will see “it’s got orange polka dots running down its back.”
“A lot of the marine leeches are fantastically beautiful,” he added.
Currie, on the other hand, specializes in bloodsucking black flies. Although smaller than leeches and perhaps not as feared, they are vastly more numerous and arguably more hated.
Both scientists hope that the upcoming exhibit might leave visitors, if not more inclined to love blood-feeders, perhaps more able to tolerate sharing the planet with them.
Dracula is included in the exhibit, by the way, along with fantasies of vampires from many cultures. The Royal Ontario is a science and culture museum, and imaginary creatures are welcome. There are a lot of them to keep Dracula company, like the ancient utukku of Mesopotamia, the Icelandic draugr and the recent (1995) chupacabra, first sighted in Puerto Rico.
What are they like? Awful, all of them, and bloodthirsty, of course. The Penanggal of Malaysian folklore is at the top of the list of the most disgusting. It’s a floating head with dangling entrails. Happy Halloween.
The bloodsuckers of reality may be less horrific, or not. But they are certainly far more numerous. There are 30,000 animal species that feed on blood. You may ask: Why so many? Kvist’s question is: Why so few?
If blood is so plentiful and energy-rich, and it is, why didn’t more of the 1.3 million known species get in on this diet choice during the course of evolution?
The answer is that drinking the blood of other creatures while they are alive, and might possibly swat you, is not as easy at it looks.
Some difficulties are obvious (see: swatting). And although blood often flows close to the surface of the body, you have to get through the skin to draw it out. Thus, the many drills, biting parts and teeth of blood-feeders.
But like bank robbers, blood-feeders need to be stealthy. And there’s the clotting problem: you have to keep the blood flowing if you want to suck it.
Then there are nutritional obstacles. Blood lacks enough B vitamins, and even insects need them. Although blood transports B vitamins, it’s always dropping the nutrients off where they are needed. Siddall said red meat has roughly 1,000 times as much B12 as blood, ounce for ounce.
That’s not all: Iron can be toxic, and blood has so much that, as a plasma-diner, it’s dangerous to have a lot of somebody else’s in your digestive system.
Leeches have solutions for all these problems. Their saliva is a complex mixture of many, many compounds, including anticoagulants and anesthetics, which has left them in great demand among medical researchers.
Leeches solve the vitamin problem by playing host to bacteria in their stomachs that create B vitamins. (So do ticks and lice and other blood-loving creatures). And leeches have several adaptations to protect themselves from iron, including a type of tissue that binds iron to proteins to make it less toxic.
“If you think of evolution as beautiful, this is one of the more beautiful systems,” Kvist said.
He also has advice for when you get bitten. Do not pull the leech off, or shake salt or lemon juice on it, or burn it with a cigarette. All of these things are profoundly disturbing to the leech, which may then vomit up the contents of its stomach while still plugged into your bloodstream. That could cause an infection.
Kvist suggests letting the leech fill up and fall off on its own, but even he doesn’t believe anyone will follow this advice. A less disturbing alternative is to slowly and methodically pry off the leech’s mouth with something like a credit card, sort of the way you try to get an old registration sticker off a windshield.
Kvist is a treasury of information on leeches. They are descended from earthworms, and the ancestral wormy parasite from which they all came, 250-300 million years ago, was a blood-feeder. There are now 700 species of leeches, and 200 of them no longer feed on blood. They eat insects and other little creatures.
What about the other 29,500 species of blood-feeders? There is the famous vampire bat, which nicks the ankles of cattle and other animals and laps the trickling blood. Its anticoagulant is called draculin.
But how about vampire finches, one of the many finches in the Galápagos? They peck the tails of boobies until they bleed. This may not sound like the best way to make a living, but one report said there are more vampire finches than any other kind of finch in the Galápagos, and they sometimes swarm their food sources.
There are also blood-loving snails, fish and moths. But insects and ticks are by far the most numerous blood-feeders. They make up 25,000 of those 30,000 species, including bedbugs, fleas, lice, tse tse and other flies, and the ubiquitous mosquito.
The black flies that Currie studies have reputedly killed large mammals when swarming them (perhaps by shock rather than what is delicately referred to as exsanguination).
The flies are herculean processors of organic material in streams and rivers — “ecosystem engineers,” Currie said. The larvae, which live in the water, attach themselves to rocks by one end, and use feathery appendages at the other end as a kind of net to catch the tiniest bits of edible detritus — motes that are too small for fish and other insects.
The larvae clean the appendages with their mouths, eating all the little bits they collect. But they only extract about 20% of the nutritional value of the catch. Black fly larvae feces, nice little compact pellets, still have 80% of the original goodness.
And here’s the great news: Those pellets are big enough to feed other creatures. Millions and millions and millions of black fly larvae make tons and tons and tons of delicious edible poop, keeping ecosystems healthy and thriving so you and your children can enjoy swimming in mountain streams.
Black flies don’t transmit disease in North America, but in Africa and Latin America, they carry a parasite that causes river blindness. Other blood-feeding insects — such as mosquitoes and ticks — spread a host of devastating diseases: malaria, sleeping sickness, Lyme, babesiosis, Zika, dengue, encephalitis and others.
Black flies are now spreading north, as climate change affects ecosystems. This could be bad news for some birds, like the red knot, which nests in the Arctic, Currie said. Chicks have no real defense against the insects.
Looking at the toll insects take when they drink blood kind of makes leeches look like humanity’s friend. True, some land varieties will drop down on you from trees as you are walking through a rainforest. But they don’t spread human diseases.
And if you keep them as pets and you forget to buy leech food — Kvist buys cattle blood and sausage casing from the butcher, and makes tasty little blood balloons — you can always feed them your own blood. Kvist does so, on occasion, as do other leechologists.
One of the current uses of leeches is to assist in wildlife surveys. Scientists can recover the DNA of the last four animals a leech has fed on from its stomach. This provides a nice snapshot of what’s running around the environs, and scientists don’t have to tramp through the jungle chasing animals or setting up camera traps — or worse, real traps.
“Leeches blow camera traps away,” Siddall said.
He and Kvist are off to Madagascar in November to collect leeches in an area that is being eyed for its conservation potential. Knowing what inhabits the potential park is essential.
Fortunately, “there is a horde of leeches in this park,” Siddall said, so the researchers won’t need to track down actual animals that live there, just the leeches.
And that is easy: “They find us.
This article originally appeared in
.