White men can’t jump, but earth leeches can. This is now a scientific fact; after centuries of anecdotal reports, the parasites have been caught on video jumping from leaves in the madagascar rainforest.
The record was first taken in 2017 by Mai Fahmy, a researcher now at the American Museum of Natural History. She chanced upon a leech that was stretching its body in search of a host, a behavior known as “searching”. The adventurous leech was found in Madagascar’s Ranomafana National Park.
Fahmy pulled out her phone and caught the leech creeping forward before bouncing off the leaf and landing a flail or two on the forest floor. The footage – as well as a video from 2023 showing the stunt – was published today in Biotropics.
“Even when I was in the field in Madagascar collecting leeches for blood meal analysis, I was under pressure to try to see if we could get another video to support the claim we made in the paper,” Fahmy said. By publishing the research, the team confirms anecdotal evidence that terrestrial parasites (at least spp Chtonobdella fallax) jump in search of a warm, blood-filled morsel to feed on.
Leaping leeches even made it into the chronicles of the famous 14th-century explorer Ibn Battuta, who documented leech behavior in Sri Lanka, suggesting that the behavior may have evolved independently among different terrestrial leeches. But by the mid-20th century, the notion of jumping leeches was viewed more skeptically in scientific publications.
“A lot of the history of this basically boils down to this question: ‘What exactly is a jump?’ For hundreds of years, there have been anecdotes from really extremely well-trained observers about jumping leeches,” said Michael Tessler, an invertebrate zoologist at the American Museum of Natural History and Medger Evers College, in a phone call with Gizmodo .century, at the beginning of the 19th century, almost every leech biologist who looked at these things said, ‘There’s no way they can jump.‘“
It was no secret that leeches sometimes fell on their hosts, but the question on the table was one of intentionality: Do the leeches expend energy to shoot at a given target (or simply into the air), or do they roll over and let gravity take over? them? Video evidence now documents the parasites doing just that, curling up and then hurtling off into the unknown. The animals are certainly moving outward from their leafy launch pad and – the team argues – perhaps slightly upwards. In other words, they jump.
Tessler said leeches likely jump in search of a host. After animals seek movement or warmth from a potential meal, they may jump as a sort of leap of faith toward the host.
Fahmy has been bitten by leeches before, including at least one instance where one of the parasites landed in her eye. Leeches like to go around the eyes, she said. After capture, blood samples can be taken from the animals to better understand the animals in the rainforest. A leech is essentially mobile environmental DNA laboratory.
“I will return to Madagascar in the coming years,” Fahmy said. “I’ll keep my eyes on the leeches. We know so little about their biology, their natural history, their behavior. They are full of secrets.”
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