Two species that hunt each other learned to live as one
En una cueva de azufre en la frontera entre Albania y Grecia, la naturaleza ha reescrito una de sus reglas más antiguas: dos especies de arañas que normalmente se cazan entre sí han tejido juntas una red de más de 106 metros cuadrados, habitada por 110.000 individuos. Lo que los científicos documentaron allí no es solo un hallazgo biológico extraordinario, sino una pregunta filosófica sobre cuánto de nuestro comportamiento —incluido el humano— está dictado por la naturaleza y cuánto puede ser reconfigurado por las circunstancias. En los lugares más extremos del mundo, la vida parece encontrar formas de cooperar donde antes solo existía la depredación.
- Dos especies de arañas que en condiciones normales se cazan mutuamente conviven en paz dentro de una misma red, desafiando décadas de conocimiento sobre comportamiento aracnológico.
- La escala del hallazgo es perturbadora: una estructura del tamaño de media cancha de tenis, tejida por 110.000 arañas en un ambiente sin luz, sin oxígeno limpio y saturado de sulfuro de hidrógeno.
- El ecosistema entero funciona al margen del sol —las bacterias quimiosintéticas sostienen una cadena alimentaria que culmina en 2,4 millones de mosquitos, presa suficiente para mantener estable a toda la colonia.
- Los investigadores proponen que la oscuridad total reduce la percepción visual entre depredador y presa, y que la abundancia de alimento elimina la competencia, creando condiciones únicas para una cooperación sin precedentes.
- El descubrimiento obliga a replantear qué otros acuerdos cooperativos pueden estar ocurriendo ahora mismo en las miles de cuevas sin explorar del planeta.
En una cueva de azufre en la frontera albanesa-griega, los exploradores encontraron en 2022 algo que la biología no tenía categoría para describir: una red de más de 106 metros cuadrados habitada por aproximadamente 110.000 arañas de dos especies que, en el mundo exterior, serían enemigas naturales. El hallazgo fue analizado por equipos internacionales y publicado en la revista Subterranean Biology como uno de los descubrimientos más sorprendentes de la biología subterránea reciente.
Las dos especies —Tegenaria domestica y Prinerigone vagans, unas 69.000 y 42.000 individuos respectivamente— comparten una red estable en lugar de cazarse mutuamente. La red no es una estructura continua sino un mosaico de trampas en forma de embudo interconectadas, una arquitectura que permite capturar más presas, distribuir el riesgo ante depredadores y aprovechar el espacio con mayor eficiencia de lo que lograría cualquier araña en solitario.
La cueva en sí es un mundo aparte. Sin luz solar, con temperaturas de 26 grados y aire saturado de sulfuro de hidrógeno, la vida aquí no depende de la fotosíntesis sino de la quimiosíntesis: bacterias que extraen energía directamente de los compuestos químicos del entorno. Esas bacterias sostienen larvas de insectos que maduran en mosquitos —unos 2,4 millones— que quedan atrapados en la red y alimentan a toda la colonia.
Los científicos atribuyen esta convivencia inédita a tres factores: la oscuridad total que dificulta que una especie identifique a la otra como presa, la abundancia de alimento que elimina la competencia directa, y las condiciones extremas que parecen favorecer estrategias adaptativas imposibles en entornos convencionales. El descubrimiento no solo desafía lo que se sabía sobre las arañas, sino que abre una pregunta más amplia: ¿cuántas otras formas de cooperación inesperada aguardan en las cuevas que aún no hemos explorado?
In a sulfur cave straddling the border between Albania and Greece, scientists have documented something that should not exist: a web spanning more than 106 square meters, woven and inhabited by approximately 110,000 spiders of two species that, under normal circumstances, hunt alone and hunt each other.
The discovery, first observed by cave explorers in 2022 and later analyzed in detail by international research teams, has been published in the journal Subterranean Biology as one of the most striking findings in recent underground biology. What makes it remarkable is not merely the scale—a structure comparable to half a tennis court—but the fact that it houses both Tegenaria domestica and Prinerigone vagans living together in stable coexistence. Around 69,000 individuals of the first species share the web with approximately 42,000 of the second. In the world above, these two would be predator and prey. Here, they have developed a cooperative arrangement never before documented in these animals.
The Sulfur Cave itself is an extreme environment. Hydrogen sulfide saturates the air. Temperatures hover near 26 degrees Celsius. Sunlight never penetrates. Life here does not depend on photosynthesis but on chemosynthesis—a process in which sulfur-oxidizing bacteria extract energy directly from the chemical composition of the cave itself. These bacteria form the base of an entire food chain. They produce organic matter that feeds insect larvae. Those larvae mature into adult insects that become trapped in the web. The spiders feed on the insects. The cave supports an estimated 2.4 million non-biting mosquitoes, ensuring the colony has sufficient prey to remain stable.
The web itself is not a single continuous structure but rather a mosaic of individual funnel-shaped traps connected to one another. This architecture allows the colony to capture more prey than solitary spiders could manage alone, to distribute risk from predators across many individuals, and to use the available space with greater efficiency.
Scientists believe the unprecedented coexistence stems from the cave's total darkness, which reduces visual perception between potential predators and prey, diminishing the likelihood of attack. The abundance of food—those millions of mosquitoes—reduces competition between the two species. And the extreme conditions themselves appear to favor unusual adaptive behaviors that would never emerge in temperate, well-lit environments. Where spiders are normally solitary creatures, and where permanent collective webs are extraordinarily rare, this cave has produced something that challenges fundamental assumptions about spider behavior.
The discovery raises questions about what other cooperative arrangements might exist in the world's unmapped caves, and what environmental pressures might trigger solitary animals to abandon their nature and build something together.
Citas Notables
Two normally solitary spider species developed stable coexistence within the same giant web, something never documented before in these animals— Subterranean Biology research team
La Conversación del Hearth Otra perspectiva de la historia
Why would two spider species that normally prey on each other suddenly stop?
The darkness helps. Without sight, the predatory instinct doesn't activate the same way. But it's more than that—there's simply too much food. When mosquitoes are abundant, there's no hunger driving aggression.
So it's not cooperation born from choice, but from circumstance?
Exactly. The cave creates conditions where cooperation becomes the path of least resistance. The spiders aren't choosing to be peaceful. They're responding to an environment where solitude is harder than togetherness.
How do they even build something this large together?
Each spider builds its own funnel trap, its own small web. But they connect them. The structure grows organically, each individual contributing without any central coordination. It's like thousands of people building walls next to each other until a city emerges.
And the food chain—it all starts with bacteria eating sulfur?
Yes. The bacteria are the foundation. They convert chemical energy into organic matter. Everything else—the insects, the spiders—is built on that conversion. It's a completely different world from the one we live in.
What happens if the mosquito population crashes?
That's the real question. The colony is stable now, but it's entirely dependent on that food source. The system is elegant but fragile.