By: Tracey Romero, For Geekadelphia

While they may seem straight out of a horror film with their slimy, wormy exterior, multiple jaws and thirst for blood, leeches have sophisticated depths that might surprise you. From their instrumental role in both ancient and modern medicine to their innate motherly instincts, leeches have fascinated scientists for centuries.

Hoping to spread some love for these tiny annelids, Robert Hicks, director of the Mütter Museum and Historical Medical Library of the College of Physicians of Philadelphia and Daniel Shain, professor of zoology and chairman of the Biology Department at Rutgers University are leading an illustrated presentation, Un-Leeched: The History and Science of Leeches, at the Wagner Free Institute of Science of Philadelphia on Wednesday, October 26, 2016.

Shain, who has traveled the world studying leeches, will discuss the more than 600 known species of leeches, including a rare, foot-long terrestrial leech he discovered that makes its home in New Jersey. He will also share cool facts about their habitats and behavior.

For instance did you know that not all leeches suck blood? Or that they are all hermaphrodites and after mating, both leeches will lay eggs? Some species even exhibit strong parenting instincts by protecting their cocooned eggs from predators and by letting little hatchlings hitch a ride on them until they get their first meal.

Hicks who shares his office with his pet medicinal leech, Horatio, will focus on medicine’s love/hate relationship with them. For thousands of years, they were used in the practice of bloodletting to treat all kinds of infections and illnesses. With the dawn of modern medicine, however, this practice was deemed barbaric. It wasn’t until the 1970’s and the founding of microsurgery that leeches made a comeback. Today, surgeons will use leeches to help improve blood flow after transplants, reattachments and reconstructions.

Hicks said, take for example, a severed finger. After the surgeon re-attaches it, if there is good arterial inflow, but poor venous outflow, the veins will clog with blood and gangrene will set in.

“The question becomes how do you get the body to treat it like a finger again?” he said. “That is where the leeches come in.”

Not only does the leech siphon off the pooled blood, the chemicals secreted in its saliva improve blood flow by widening the blood vessels (vasodilation) and by preventing clotting (anticoagulation). This complex saliva also contains an anesthetic so you don’t feel the bite, he explained.

Live leeches can be found in the pharmacies of local hospitals like Temple University Hospital and the Hospital of the University of Pennsylvania. According to James Bradley, professor of surgery at the Lewis Katz School of Medicine at Temple University and a plastic and reconstructive surgeon at Temple University Hospital, medicinal leeches are ordered from the pharmacy when a skin/muscle/fat flap reconstruction is threatened because of venous congestion.

“The leeches are used one at a time. When they are filled up, they fall off and a new leech is applied every 30 minutes,” he said. “The leeches act as a bridge to avoid flap failure. Once the veins rechannel in a few days, the leeches are no longer needed.”

At the Hospital of the University of Pennsylvania, surgeons use leeches for similar indications and the pharmacy always keeps a colony of live leeches on standby. Stephen J. Kovach, a surgeon at the Hospital of the University of Pennsylvania, explained that it is pretty rare that they will use them, but when they do, there is no time to wait for leeches to be shipped.

“There is no primary leech therapy, but we use them as a bailout,” he added.

Bradley agrees that leech therapy is a last resort, but said it does have its place. At Temple, he said, they probably use leeches three to four times a year.

Fascinated yet by these complex creatures? Want to show them some love? The interactive presentation at the Wagner will include a leech beauty contest where you can vote on their coolest characteristics as well as a chance to face your fears and come face to face with some live leeches. The lecture starts at 6 p.m. Register for this free event here.

Un-Leeched: The History and Science of Leeches

Wednesday, October 26 @ 6:00 p.m. to 7:30 p.m.

Wagner Free Institute of Science, 1700 West Montgomery Avenue

Register via Eventbrite