The Cave That Time Forgot

Water Scorpion Attacks Crustacean Isopod

I've told you about Lake Vostok, the sub-glacial freshwater lake in Antarctica that had been cut off from Earth's ecosystem for up to 20 million years. We are still waiting to discover if there are any weird lifeforms there. [See "One of the World's Largest Lakes -- Unseen by Humans"

But there is another place -- this one on land -- that also had been completely cut off from Earth's atmosphere and environment for millions of years. However, in this case, we have actually discovered and identified the weird lifeforms there. Does it include dinosaurs or Mole People? I will answer that at the end of this entry.

While surveying land through drilling in 1986, Movile Cave was discovered about 20 meters below the surface near Mangalia, Romania. Because it seemed poisonous and lifeless, it was sealed. In 1989, a scientist entered to have a closer look, and discovered an ecosystem that had evolved completely independent of the world above. Water and air in the cave had been cut off from the outside world for about 5.5 million years. This means there has been no sunlight, and the atmosphere is more like that of an alien planet: Less than half as much Oxygen as Earth's atmosphere, as much as 100 times the amount of Carbon Dioxide, 2% Methane, and significant amounts of Hydrogen Sulfide and Ammonia. 

What lifeforms can exist in such an ecosystem, and what processes must be used to deal with the absence of sunlight and plants, and the presence of gases and other compounds that are poisonous to life as we know it?

Aquatic Isopod

Lifeforms

The cave has at least 48 different species, all invertebrates (no internal skeleton): 30 terrestrial and 18 aquatic -- and 33 of these exist nowhere else on the planet besides this cave. All creatures in the cave are sightless and colorless (pale white or translucent). Many have outsized antennae to compensate for the lack of visual cues, and outsized appendages to help manipulate around unseen obstacles and dangers. Some of the creatures have chemical and electrical sensors. The species include:

• Springtails -- There are 3 of these creatures, which used to be classified as insects until it was discovered that they are not.

• Spiders -- There are 5 unique species, and they spin webs even though there are no flying insects.

• "Scorpions" -- There is 1 Water Scorpion and 3 terrestrial Pseudo-Scorpions, all of them unique to this cave. They are predators that look like scorpions, but they are not.

• Centipedes -- The animal at the top of the food chain is one of 3 centipedes. There also is a Pseudo-Centipede.

• Beetles -- There are 4 species, all unique to this cave.

• Worms -- There is 1 terrestrial species, and 7 aquatic ones, including a Leech.  

• Other Species -- There is a Snail (or Slug), a Millipede, a Tick, a Shrimp, Two-Pronged Bristletails (I don't know what that is), and small Crustaceans (including a transparent Crab and Lice) and microscopic denizens. And let's not forget the Bacteria on which the entire life cycle of the cave depends.   

Translucent Louse

Biological Processes

Chemosynthesis

How is this life cycle maintained so animals can prosper without light or plants? The absence of sunlight precludes the process of Photosynthesis, which plants use to convert sunlight and Carbon Dioxide into energy and Oxygen, which is then used by animals to live. Chemosynthesis creates this energy through chemical reactions only. Bacteria in the cave convert substances such as Ammonia and Sulfides into organic compounds that can then be used by animals. 

• Methanotrophs use Methane (CH₄) as their source of Carbon (C), combining it with Oxygen (O₂) to create Formaldehyde (CH₂O), which is then used to create organic compounds, such as the amino acid Glycine (NH₂CH₂COOH).

• Autotrophs use Water (H₂O) with Hydrogen Sulfide (H₂S), Carbon Dioxide (CO₂), and Ammonia (NH3) in the air to produce complex organic compounds (carbohydrates, fats, proteins, etc.) and their own chemical energy, which are eventually consumed by the cave's residents, who are then consumed by predators. The area itself increases over time because the Bacteria dissolves the Hydrogen Sulfide with Water to produce Hydrosulfuric Acid, which eats away at the surrounding limestone cave walls.

There are other caves in the world where similar blind, colorless invertebrates exist; however, Movile Cave is the only known terrestrial place on Earth with an ecosystem is based entirely on Chemosynthesis rather than Photosynthesis or dependency on the outside environment.

Criptos Anomalans Centipede

One final note: I realize that some of you might be a bit disappointed by these findings, because they do not include the discovery of dinosaurs or a society of Mole People. The lack of dinosaurs can be explained by the fact that they died out 65 million years ago, and Movile Cave was formed only 5.5 million years ago. As for the Mole People, there still might be other caves to be discovered.