Hidden Worlds

There is no light and very little oxygen in the Movile cave in Romania. There is a lake of warm water rich in hydrogen sulfide that reacts with oxygen in the air to create sulfuric acid that eats away at the limestone enlarging the cavern and depositing gypsum on the walls. And yet life clings tenaciously on the edges of this poisonous environment.

There are 48 life forms from microbes to insects that inhabit the cave, 30 of which were unknown until the cave was discovered in 1986. At the base of food chain are bacteria that synthesize organic molecules from the carbon dioxide in the air and energy derived from the sulfuric acid reaction. Chemical energy is the driving force of ecosystem, instead of absent sunlight. The bacteria grow along with fungi in white mats floating on methane gas bubbles on the surface of the water, or clinging to the sides of cavern in the “air bells.”

All the creatures are without pigmentation and sight, though some retain empty eye sockets. They have developed elongated legs and antennae to feel their way around. Many have developed protections against the poisonous hydrogen sulfide. The water scorpion is covered with a thick layer of bacteria that ingest sulfur.

There are animals that live on the cave walls around air bells and those that live in the water. In each case there are plant eaters and meat eaters. The plant eaters graze on the microbial mats. The aquatic animals live just below the waters surface not more than two inches. They include a variety of flatworms, roundworms, microscopic isopods and snails as well as visible isopods, insects and shrimp-like crustaceans, none of which are more than half an inch long. Three carnivorous species also live in the water: a flatworm with a triangular head, which eats crustaceans; a reddish brown blind leech, colored by the hemoglobin in its blood, which eats flatworms; and the water scorpion, which eats virtually anything.

On the walls are spiders, pseudo-scorpions, millipedes, beetles, and more isopods. Many of the smaller animals feed on the wall and the floating mats. The top predator of the cave wall is the centipede, which feeds on mat eaters.

These creatures have developed in isolation for 5 million years and bare very little similarity to the microorganisms and animals outside of the cave. Many of the terrestrial creatures are more similar to ancestral forms that inhabited the land in more tropical times. The cave spiders are most closely related to those that live on the Canary Islands and in Northern Africa.

For 5 million years life has not only survived but created new ways of surviving. Long before people were people, the life forms in this cave were shut off from the sun and the outside world.

What forms will life take if people are either evolved into something new or extinct? Out of what bubble in time will new inheritors of the earth crawl to inhabit whatever environment is left to them? Whatever occurs there will be life.

Information taken from an article in The Sciences (Nov/Dec. 1994) by Robert Zimmerman and Wendy Marston.