Not just bloodsuckers! Leeches join the club of jumping invertebrates. Researchers compare their jumps to backbending cobras and shed light on a long-standing scientific debate. Learn more about the science!
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| Leaches with superpowers; scientists capture footage of leeches jumping from leaf to leaf. This is a common behavior or a rare occurrence. |
For centuries, tales of "flying leeches" have been whispered in hushed tones, dismissed as mere folklore. But a new study published in Biotropica puts those whispers to rest, providing the first definitive video evidence of leeches jumping from leaf to leaf.
The research, led by Mai Fahmy of the American Museum of Natural History and Fordham University, captures a terrestrial leech species contorting its body and propelling itself through the air. This groundbreaking discovery settles a scientific debate that has spanned over 100 years.
"We've seen anecdotal reports of leech jumps for a long time," says Fahmy. "People would say they were walking through the forest and felt something land on them. The explanation was always that the leech hitched a ride on a passerby or fell from a branch." This new video footage, however, paints a different picture.
The leeches in the video exhibit a clear jumping motion, with their bodies visibly coiling and then extending to launch themselves. This behavior not only dispels the myth of the passive, hitchhiking leech but also opens up new questions about their hunting strategies and ecological roles.
Leaping Leeches in Action
During two separate expeditions to Madagascar in 2017 and in 2023, Fahmy recorded footage of leeches from the genus Chtonobdella coiling back on a leaf and then taking off. Fahmy and coauthor Michael Tessler, an assistant professor at CUNY's Medgar Evans College and a research associate at the Museum, compare this motion to a "backbending cobra," or to a spring being pulled back. In both cases, the leech keeps its body extended as it soars through the air to the ground, in a notable departure from their usual inchworm-like movements.
"Essentially, it executes a graceful jump but with a seemingly hard landing," Tessler said.
Not the Only Jumping Invertebrates
Several other worm-like invertebrates can jump, including the legless larvae of gall midges (Asphondylia sp.), which assume a loop posture before propelling themselves into the air, the larvae of Mediterranean fruit flies (Ceratitis capitata), "skipper flies" (Prochyliza xanthostoma), and several caterpillars, including Lymantria monacha and Orgyia leucostigma. While naturalists and leech biologists have long argued about the ability of terrestrial leeches in the family Haemadipsidae to jump, with some making observations of leeches leaping in their travel notes, there has been little concrete evidence until now.
Fahmy collected the jumping leech she observed on the 2023 trip, and the researchers identified it as Chtonobdella fallax, a common species in Madagascar. The larger Chtonobdella group of leeches to which C. fallax belongs can be found across Madagascar, the Seychelles, the Malay Archipelago, and the South Pacific Islands.
"We do not know how often this may happen or whether these leeches use this ability to seek out hosts, but, given that we caught multiple jumps in two short recordings, this behavior may be common for this species," said Tessler, who studied leeches extensively as a graduate student in the comparative biology Ph.D. program at the Museum's Richard Gilder Graduate School.