Tens of thousands of undiscovered earthworm species may be thriving in the world’s soil, as scientists warn that it could take over a century to uncover them all.
Earthworms are vital for nutrient recycling in ecosystems, and researchers express concern that unidentified species may vanish before being documented.
While scientists have officially recognized more than 5,700 species and subspecies, Thibaud Decaëns from the University of Montpellier believes this number is vastly underestimated. His observations in the Amazon revealed a surprising diversity of earthworms.
To investigate further, Decaëns and his team conducted extensive sampling surveys in French Guiana, often accessing hard-to-reach areas by helicopter and dedicating up to two weeks to collect samples from one-hectare plots.
“We have only recorded 55 described species in French Guiana,” Decaëns noted, “yet there are likely at least 2,000 species in that region alone.” Additional studies in France corroborated the notion that earthworm diversity is significantly underestimated.
In a complementary phase of their research, the team collaborated with a statistician to estimate the number of undiscovered earthworm species worldwide based on current records and the taxonomy classification rate.
“Globally, we estimate that at least 30,000 species of earthworm inhabit our planet,” Decaëns stated, cautioning that it could take up to 120 years to classify them all, given the current number of taxonomists.
“Understanding the number of species and their distribution is crucial for conservation efforts,” added team member Helen Phillips from the University of Helsinki.
Keiron Brown from the Biological Recording Company echoed these concerns, stating that the research underscores the significant knowledge gap surrounding earthworms: “It is astonishing that we’ve fallen so far behind in understanding such an ecologically essential group of organisms.”
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