Deadly centipede discovered in a cave that hasn't seen daylight in 5.5 million years

A venomous centipede, Cryptops speleorex, was discovered in Romania’s Movile Cave, isolated for over 5.5 million years.
It seems likely that this centipede, dubbed the “king of the cave,” is the largest predator there, measuring 46-52 mm and adapted to toxic, lightless conditions.
The evidence leans toward the cave hosting a unique ecosystem, with 51 invertebrate species, 34 endemic, supported by chemosynthetic bacteria.

Movile Cave, located 65 feet below Romania’s surface, was discovered in 1986 by workers searching for a power plant site.

It has been sealed off from daylight for over 5.5 million years, creating a time capsule of evolution.

The cave’s atmosphere is warm, moist, and low in oxygen, with high levels of toxic gases like hydrogen sulfide and methane, making it inhospitable for most life forms.

The Centipede and Its Adaptations

Cryptops speleorex, nicknamed the “king of the cave,” thrives in this extreme environment.

Measuring around 2 inches (46-52 mm), it is the largest predatory arthropod in the cave, equipped with venomous bites for hunting.

It has evolved longer antennae and specialized saw teeth on its legs, aiding navigation and predation in complete darkness. Its genetic divergence from surface relatives suggests millions of years of adaptation to the cave’s poisonous conditions.

Larger Than Expected

Interestingly, C. speleorex is larger than its surface-dwelling relative, Cryptops anomalans, challenging the common assumption that cave-dwelling animals are smaller.

This suggests isolation can lead to larger size, possibly due to reduced competition, offering a fresh perspective on evolutionary biology.

The Deadly Centipede Discovery

Movile Cave, hidden 65 feet below Romania’s surface, has been cut off from daylight for 5.5 million years, creating a subterranean world where life thrives despite toxic conditions.

Discovered in 1986 by workers scouting for a power plant site, this cave is a time capsule of evolution, with oxygen levels at half normal and gases like hydrogen sulfide and methane dominating.

Movile Cave, located in Dobrogea, Romania, was formed during the Neogene period and has remained isolated for over 5.5 million years, a fact supported by geological studies.

Its discovery in 1986 by workers searching for power plant locations was accidental, revealing a warm, moist environment 65 feet underground, with oxygen levels roughly half of surface conditions and high concentrations of carbon dioxide, methane, and hydrogen sulfide.

These conditions, lethal to most life, are mitigated by chemosynthetic bacteria, which convert chemical energy into organic compounds, forming the base of the food web.

The cave’s isolation has led to a biodiversity hotspot, with over 50 invertebrate species, 34 endemic, making it one of the most species-rich caves globally.

This isolation, lasting millions of years, has fascinated scientists, each expedition uncovering new insights into extremophile life.

The Unique Ecosystem of Movile Cave

The ecosystem of Movile Cave is a complex web, driven by chemosynthetic bacteria that feed on carbon dioxide and methane, a process detailed in recent studies.

These bacteria are consumed by detritivores and filter feeders, which in turn support carnivores like spiders, scorpions, earthworms, snails, slugs, and leeches. Specific inhabitants include:

Species Type	Examples	Adaptations
Cave Spiders	Troglohyphantes	Long legs, sensitive hairs for vibration detection
Cave Scorpions	Euscorpius sp.	Reduced eyes, reliance on chemoreception
Earthworms	Various	Adapted for burrowing, nutrient cycling
Snails and Slugs	Unspecified	Shells or bodies suited for high humidity
Leeches	Cave leeches	Blood-sucking, likely feed on arthropods

With 51 invertebrate species, 34 unique to the cave, Cryptops speleorex’s discovery as the top predator adds a new layer, controlling populations and maintaining ecological balance.

Its role, as the largest at 46-52 mm, underscores the cave’s ability to support complex life forms despite the absence of sunlight, a testament to evolutionary adaptability.

Discovery and Description of Cryptops speleorex

Cryptops speleorex was discovered through expeditions led by explorers Serban Sarbu and Alexandra Maria Hillebrand, with specimens studied by an international team including Dr. Pavel Stoev from Bulgaria, Dr. Bruno Buzatto from Finland, and others from Austria and Romania.

Initially mistaken for Cryptops anomalans, a common European surface species, genetic and morphological analysis revealed distinct differences, classifying it as new.

Measuring 46-52 mm, it’s larger than C. anomalans (up to 25 mm), with elongated appendages, more coxal pores, and saw teeth on the ultimate leg’s tibia, adaptations for cave life.

Its venomous bites, delivered via forcipules, immobilize prey like spiders and beetles, reinforcing its apex predator status.

Named “speleorex” from Latin for “cave king,” it reflects its dominance, with genetic divergence confirmed by mitochondrial (COI, 16S rDNA) and nuclear (28S rDNA) markers, indicating millions of years of isolation.

Challenging Evolutionary Assumptions

Cave-dwelling animals are typically smaller and less robust than surface counterparts due to limited resources.

However, Cryptops speleorex, at 46-52 mm, is larger than C. anomalans, suggesting isolation can lead to “island gigantism,” a phenomenon seen in isolated populations.

This challenges the notion, supported by examples like larger island species, that cave environments always reduce size.

Reduced competition or selective pressures for larger size in predation may explain this, prompting reconsideration of evolutionary biology in isolated ecosystems.

Further research, as noted in recent studies, is needed to explore these dynamics, highlighting the complexity of evolutionary outcomes.

Adaptations and Role in the Ecosystem

Cryptops speleorex’s role as apex predator involves preying on smaller cave inhabitants like spiders and beetles, using venomous bites for efficiency.

Its elongated antennae detect vibrations and chemicals in darkness, while saw teeth on legs may aid in climbing or burrowing, adaptations detailed in morphological studies.

With no natural predators, it maintains ecological balance, controlling arthropod populations.

Genetically, its divergence from surface relatives, confirmed by DNA markers, offers insights into isolated evolution.

Its tolerance for low oxygen and toxic gases, a subject of ongoing research, could inform astrobiology, exploring life in extreme extraterrestrial environments, adding depth to its significance.