First observation that leeches can jump

June 20 () –

A new study presents video evidence that at least one species of terrestrial leech can jump, a behavior that scientists have debated for more than a century.

Researchers from the Natural History Museum, Fordham University, and Medgar Evers College at the City University of New York (CUNY) published the images and corresponding analysis in Biotropica magazine.

“We believe this is the first compelling evidence that leeches can jump and do so with visible energy expenditure,” he said. it’s a statement lead author Mai Fahmy, a Museum visiting scientist and postdoctoral researcher at Fordham University. “There have been previous accounts of leeches jumping, even on people, but those reports were often explained as leeches simply attaching themselves to passers-by when they brushed against bushes or fell from an overhead branch. This study dispels that argument“.

During two separate expeditions to Madagascar in 2017 and 2023, Fahmy recorded images of leeches of the genus Chtonobdella curling into a leaf and then taking off. Fahmy and co-author Michael Tessler, an associate professor at CUNY’s Medgar Evans College and a research associate at the Museum, compare this movement to a “backbend cobra” or a spring being pulled back. In both cases, the leech keeps its body extended as it rises through the air to the ground, in a notable change from its usual measuring caterpillar movements.

“Basically, he executes a graceful jump but with a seemingly hard landing,” Tessler said.

Several other worm-like invertebrates can jump, including the legless larvae of gall gnats (Asphondylia sp.), which adopt a looping posture before propelling themselves into the air, the larvae of Mediterranean fruit flies (Ceratitis capitata), “jumping flies” (Prochyliza xanthostoma) and various caterpillars, including Lymantria monacha and Orgyia leucostigma. Although naturalists and leech biologists have long debated the ability of terrestrial leeches in the family Haemadipsidae to jump, and some have made observations of leeches jumping in their travel notes, so far there has been little concrete evidence.

Fahmy collected the jumping leech he observed on the 2023 trip and researchers identified it as Chtonobdella fallax, a species common in Madagascar. The largest group of Chtonobdella leeches to which C. fallax belongs can be found in Madagascar, the Seychelles, the Malay Archipelago, and the South Pacific islands.

“We don’t know how often this may occur or whether these leeches use this ability to search for hosts, but since we captured several 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 doctoral program at the Museum’s Richard Gilder Graduate School.

Understanding the general behavior of leeches is also important for conservation efforts, as more leeches (and, more specifically, the blood they ingest) are captured.) to study the biodiversity of vertebrates.

“If we can identify how leeches find and attach to their hosts, we can better understand the results of their gut content analyses,” Fahmy said. “Leeches are also often overlooked and understudied, and as a natural part of the ecosystem, “leeches themselves may need protection for conservation.”