Michael Tessler realized his life had taken an odd flip. His days had been spent not in an workplace, not out with buddies — however alone within the woods, attracting leeches.
Typically, they had been so bountiful that “it was just like the forest ground was shifting towards me,” he recalled. “Even for somebody who’s used to having swarms of leeches coming at me, it could possibly be intimidating to see that a lot of them.”
Dr. Tessler, a postdoctoral fellow on the American Museum of Pure Historical past’s Sackler Institute of Comparative Genomics, subjected himself to this horror film state of affairs for the great of science. He collected a whole bunch of leeches and analyzed their final blood meals, hoping to determine their animal victims — and thus to disclose the vary of species dwelling within the forest.
Copious leech bites later, Dr. Tessler’s sacrifice paid off. He was a co-author on two papers confirming that leeches and their blood meals provide a quick, low-cost methodology for surveying biodiversity. Such primary information could be surprisingly tough to return by, but is usually essential for making conservation selections.
“That this bloodsucking worm may immediately advance conservation efforts is one thing few would have predicted,” he mentioned.
Terrestrial leeches are present in humid areas stretching from Madagascar to southern Asia to a lot of Pacific islands. Some 70 species have been described, with many extra probably awaiting discovery.
They’re a various bunch: some are drab brown, others strikingly patterned in greens, reds and blues. Some crawl throughout the forest ground in the hunt for a meal, whereas others occupy leafy perches and leap onto unsuspecting hosts.
All of them share a style for blood. The tiny vampires might swell to 10 instances their physique weight after feeding, remodeling from agile, threadlike worms into engorged blood sausages. Remnants of a leech’s final gluttonous meal might stay in its physique for months — a boon for researchers curious to see what it beforehand consumed.
The concept of utilizing leech blood meals as an identification instrument might have been impressed by a prison case in Tasmania in 2009. Investigators recovered DNA from a blood-filled leech to hyperlink a suspect to a theft.
A number of years later, researchers printed the primary area examine exhibiting that the tactic labored to determine wildlife, too. Whereas encouraging, the preliminary examine was based mostly on a pattern of simply 25 leeches caught in Vietnam.
Wanting to see if the tactic could be relevant on a much wider scale, Dr. Tessler and his colleagues got down to conduct an investigation in Bangladesh, China and Cambodia.
Step one — assortment — was easy, mentioned Sarah Weiskopf, a biologist at the US Geological Survey and co-author of the brand new papers: “You simply get to your spot within the forest and go searching for issues crawling towards you.”
Of the hundreds of leeches Ms. Weiskopf, Dr. Tessler and their colleagues captured, 750 had been chosen for genetic evaluation. The researchers reduce out the parasites’ digestive tracts and filtered them to extract DNA.