Giant Brazilian Earthworm

More than two meters long

On May 5, 1912, an extraordinary animal was discovered near the city of Belo Horizonte in Brazil: an earthworm more than two meters long. The species later described as Rhinodrilus fafner—also known as the giant Brazilian earthworm or Minhocuçu—reached a length of 210 centimeters, a body diameter of 2.4 centimeters, and consisted of around 600 segments.

For comparison: the common earthworm (Lumbricus terrestris), which is widespread in Europe, is already among the largest of its kind at a length of up to 35 centimeters.

Despite its size, little is known about the giant Brazilian earthworm. The species was scientifically described in 1918 by the German zoologist Wilhelm Michaelsen—based on a single, poorly preserved specimen. Since then, no further individual has been clearly documented. The holotype is now kept at the Senckenberg Research Institute and Natural History Museum in Frankfurt am Main (Germany).

Giant Brazilian earthworm – fact sheet

alternative names	Minhocuçu, Minhocas
scientific name	Rhinodrilus fafner
original range	Brazil
time of extinction	1912 at the earliest
causes of extinction	habitat loss
IUCN status	Data Deficient

Missing—or already extinct?

The extreme rarity of the giant Brazilian earthworm Rhinodrilus fafner makes any assessment of its current status difficult. Many researchers assume that the species is now extinct. However, the International Union for Conservation of Nature (IUCN) lists it in the category Data Deficient (DD).

This classification highlights a fundamental problem: reliable information on distribution, population, and specific threats is lacking. A final judgment on the extinction of the species is therefore still not possible.

On top of that, targeted searches have so far been unsuccessful: at least two search expeditions in the 1960s (1967 and 1968) as well as another search in the 2010s (exact date unknown) failed to document a single specimen.

The most likely cause of its possible disappearance is considered to be the destruction of its habitat. The presumably already very restricted range around Belo Horizonte underwent profound changes in the 20th century. Urbanization, industrial development, and agricultural use have altered or destroyed natural soils and habitats on a large scale—with potentially serious consequences for specialized soil organisms such as large earthworms.

Brazil’s earthworm diversity

The case of the giant Brazilian earthworm is not unique. Brazil is home to about 305 earthworm species, of which around 85% are endemic. At the same time, about 80% of these native species are known from only one or a few sightings.

This extreme data gap shows how little is known about the soil fauna of many regions—and how quickly species can disappear without ever having been comprehensively documented.

In the state of Minas Gerais, Brazil’s Environment Ministry (Ministério do Meio Ambiente) declared two species extinct in 2003 because of missing records and ongoing habitat destruction. In addition to Rhinodrilus fafner, this also included Fimoscolex sporadochaetus.

Hope through rediscoveries

The earthworm species Fimoscolex sporadochaetus, which had already been declared extinct and was also described by Wilhelm Michaelsen in 1918, was surprisingly rediscovered in 2007.

This rediscovery prompted the scientists Samuel Wooster James and George G. Brown to fundamentally question the status of supposedly extinct species in Brazil in a study (2010). In their view, it is entirely possible that the giant Brazilian earthworm still exists—especially in the hard-to-access savanna landscapes (Cerrado) around Belo Horizonte. Fattima M. S. Moreira and Jose O. Siqueira express a similar view in their 2006 publication Soil Biodiversity in Amazonian and Other Brazilian Ecosystems.

Other examples also support this cautious hope: the North American giant earthworm Driloleirus americanus, for example, was rediscovered in 2005 after long being considered extinct. At the same time, however, there are counterexamples such as the Lake Pedder earthworm in Tasmania, which is still regarded as missing today.

A hidden life beneath our feet

Large earthworms such as Rhinodrilus fafner belong to the family Glossoscolecidae, a group of tropical soil dwellers that are often only locally distributed and require specific environmental conditions. Their hidden way of life makes them especially vulnerable to unnoticed declines.

How extraordinary such animals are is also shown by a look at Europe: the Baden giant earthworm (Lumbricus badensis) reaches lengths of up to one meter and occurs only in the southern Black Forest. Even in well-studied regions, remarkable yet sensitive species can therefore be found.

Between myth and reality

Whether the giant Brazilian earthworm still exists today remains uncertain. Its case stands as an example of a central problem in conservation: species can disappear before they are even properly studied. At the same time, rediscoveries show that supposedly lost species may in some circumstances persist—hidden in hard-to-access habitats or simply overlooked.

For conservation, this means above all one thing: without knowledge, there is no protection. Only once species are known can their habitats be preserved and targeted measures taken. The giant Brazilian earthworm thus remains not only a biological curiosity, but also a cautionary example of the major gaps in our understanding of biodiversity—especially in soil, one of the least studied habitats on Earth.

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