The video taken by a grad student in Madagascar in 2017 revealed a leech species, Chtonobdella, jumping off a leaf in the rainforest, sparking a debate in the biological community about leech locomotion. This discovery challenges the longstanding lore regarding leech behavior and movement, leading to further investigation by conservation biologist Mai Fahmy and leech specialist Michael Tessler.
Fahmy’s initial video, along with a subsequent one filmed in 2023, shed light on the contentious topic of leech jumping, which has puzzled scientists for centuries. The findings were published in the journal Biotropica, showcasing the potential of these tiny creatures to perform what appears to be jumps, a behavior previously dismissed by skeptics.
The historical accounts of “flying leeches” in Sri Lanka from the 1300s, recounted by Ibn Battuta, were met with doubt by experts in the 19th century. The current study aims to provide a rigorous definition of what constitutes a jump, focusing on the active propulsion of the organism, which has sparked lively debates among scientists in the field.
Leeches, part of the same animal class as earthworms, exhibit a wide range of colors and patterns and are known for their blood-feeding behavior. Despite their reputation for biting and causing blood loss, Fahmy finds leech bites preferable to mosquito bites and is exploring the use of leech blood samples for biodiversity assessment in Madagascar.
Of the hundreds of leech species known today, the jumping debate revolves around terrestrial leeches rather than aquatic ones. Fahmy and Tessler propose a definition of jumping that involves intentional muscular movements propelling the organism outward and upward, a concept that could apply to various organisms beyond leeches.
The candidate leech species observed in the videos from Madagascar, Chtonobdella, is a brown land-dwelling leech that exhibited a unique motion before leaping off the edge of a leaf. While some experts have interpreted the motion as a jump, others remain skeptical, highlighting the complexity and ongoing discussion within the scientific community regarding leech locomotion. Ultimately, the videos offer a fresh perspective on an age-old question, prompting further analysis and discussion among researchers.
