Two Kilometers Beneath Our Feet: This Land Animal Lives at a Record Depth

While some aquatic species are known to thrive at the depths of the planet’s deepest ocean trenches, the terrestrial record holder in this field hides at the bottom of a Georgian cave.

Plutomurus ortobalaganensis

Named Plutomurus ortobalaganensis, this record-holding creature was discovered in 2010 by the Iberian-Russian CaveX expedition while it explored the Krubera-Voronja cave system, located in the Western Caucasus and regarded as one of the deepest on Earth.

Described two years later in the journal Arthropod Reviews, it is a springtail—an arthropod that resembles an insect but actually belongs to a distinct branch of the tree of life.

Found precisely 1980 meters below the surface, P. ortobalaganensis measures no more than 4 millimeters in length. Equipped with six legs and blind, it mainly feeds on tiny species of fungi, bacteria, and decomposing organic matter, making it a crucial link in this deep cavernous ecosystem.

Another notable anatomical feature: the top of its head bears a pair of elongated antennae, which it uses to detect chemical signals and navigate a complex, lightless environment.

Colonisation récente

While most species living in total darkness are devoid of pigmentation, it turns out that the exoskeleton of P. ortobalaganensis bears a slightly grayish hue, suggesting that it colonized the deeper sections of Krubera-Voronja relatively recently from an evolutionary standpoint.

Previously, the record for the terrestrial animal evolving at the deepest known depth was held by a worm species found at depths of up to 1,300 meters in a gold mine in South Africa.

Under the waves, amphipod species thrive at depths beyond 10,000 meters. To withstand these extreme conditions, it turns out that abyssal creatures have developed several essential adaptations.