Romanian cave sealed for 5.5 million years is full of strange creatures

As humans were evolving in the plains of Africa, a different kind of evolution was taking place in Romania. The insectoid residents of Movile Cave were cut off from the outside world more than five million years ago, and that made for a very unusual ecosystem when the cave was discovered and opened up in the late 1980s. Movile Cave is believed to be
the most isolated ecosystem in the world, and scientists are only just beginning to unravel its secrets.
It has taken years to begin cataloging the creatures in Movile Cave for several reasons. First, it’s a dangerous environment with a poisonous atmosphere. Getting into the cave requires some familiarity with spelunking and diving, too. You have to go down a narrow 20-meter shaft, then climb through tiny limestone tunnels before reaching the main cavern. The Romanian government has also been very selective about who is permitted in the cave for fear of upsetting the delicate ecological balance. Only a few dozen scientists have been allowed to visit.

Waterscorpion eating a crustacean.

The few who have ventured into Movile Cave have discovered it’s crawling with life — literally. The residents of Movile Cave are not concerned with the high levels of carbon dioxide and hydrogen sulphide in the air. With just half the usual concentration of oxygen, human visitors need breathing equipment to survive. The cave gets more crowded with insects the worse the air gets.
Most creatures in Movile Cave are believed to have arrived over five million years ago when limestone sealed the entrance. Most insects have since adapted to the complete darkness by losing their eyes and pigmentation. Many have also developed longer legs and antennae to feel around in the dark. There are unique species of spiders, waterscorpions (above), centipedes, pseudoscorpions (top), leeches (below), and more.

The ecosystem relies entirely upon chemosynthetic bacteria that extract carbon from the air without the aid of light. The most numerous bacteria use carbon dioxide, and others get their carbon from methane. The bacterial film on the water and walls is where all the nutrients enter this ecosystem, and it’s the only known example of such a system. Small animals eat the slime, and larger animals eat them.

Scientists are interested in the animals in the cave, of course, but the bacteria could provide hints to how life worked when Earth was young. With the high heat, toxic air, and low light, conditions are very similar to Earth billions of years ago. Some are also exploring the idea of repurposing these bacteria to fight global warming, as carbon dioxide and methane are the biggest culprits.