Love this type of article and what it means for the odd's of life on other planets that we might have considered in hospitable simply because the conditions for our earth ecosystem to thrive are not present.
The
Horta could indeed be a thing on some planet.
The Bizarre Beasts living in Romania's Poison Cave
Movile Cave has been cut off for millions of years. Its air is thick with harmful gases, yet it is home to an array of strange animals.
...a cave that has remained isolated for 5.5 million years. While our ape-like ancestors were coming down from the trees and evolving into modern humans, the inhabitants of this cave were cut off from the rest of the planet.
Despite a complete absence of light and a poisonous atmosphere, the cave is crawling with life. There are unique spiders, scorpions, woodlice and centipedes, many never before seen by humans, and all of them owe their lives to a strange floating mat of bacteria...
..."The pool of warm, sulphidic water stinks of rotting eggs or burnt rubber when you disturb it as hydrogen sulphide is given off."
In the lake room, the atmosphere is heavy with harmful gases, principally carbon dioxide as well as the hydrogen sulphide from the water. What's more, the air is low in oxygen: it contains just 10% oxygen rather than the usual 20%...
Despite the dark and the dangerous gases, Movile Cave is crawling with life. So far 48 species have been identified, including
33 found nowhere else in the world.
There are all sorts of scuttling and slithering things. Snails and shrimps try to avoid the spiders and waterscorpions. In the air bells, leeches swim across the water and prey on earthworms.
Strangely, the worse the air gets the more animals there are. It's not at all obvious why that should be, or how the animals survive at all.
On the surface, plants use sunlight to extract carbon dioxide from the air and turn it into organic compounds. They can then use these chemicals to grow leaves, roots and bulbs. Animals then feed on these plant tissues.
Without sunlight, the animals in Movile Cave seem to be without a source of food.
In most caves, animals get their food from the water dripping down from the surface. This water can often be seen in the form of stalactites and stalagmites.
However, Movile Cave has a thick layer of clay above it, which is impermeable to water. When Lascu first visited, he could not find any stalactites or stalagmites, or any other sign of water coming from the surface.
The mystery deepened when scientists analysed the water in the cave for radioactive caesium and strontium. The 1986 nuclear accident at Chernobyl had released lots of these metals, which had found their way into the soils and lakes surrounding Movile Cave. However, a 1996 study found no traces of them inside the cave.
That means the water isn't coming from above, so it must be coming from below. It now seems that the water in Movile Cave comes from spongy sandstones where it has lain for 25,000 years.
However, this still doesn't explain how the animals in the cave survive. Tests have shown that the water flowing in does not contain any food particles.
Instead, the food comes from the strange frothy foam sitting on top of the water.
This floating film, which looks like wet tissue paper and can even be torn like paper, contains millions upon millions of bacteria known as "autotrophs".
"These bacteria get their carbon from carbon dioxide just like plants do," says Boden. "The carbon dioxide level in the cave is about 100 times higher than normal air. But unlike plants, they obviously can't use photosynthesis as there is no light."
Rather than using light as an energy source, the Movile bacteria use a process known as chemosynthesis.
"They get the energy needed… from chemical reactions: the key ones being the oxidation of sulphide and similar sulphur ions into sulphuric acid, or the oxidation of ammonium found in the groundwaters to nitrate," says Boden.
These chemosynthetic bacteria help explain why the cave is so large and the air is so thick with carbon dioxide.
"Sulphuric acid actually erodes the limestone, which is gradually making the cave bigger," says Boden. "The process releases carbon dioxide, which is why levels are so high."
Another major group of bacteria get their energy and carbon from the methane gas that bubbles up through the waters of the cave. They are called methanotrophs.
Boden describes methanotrophs as "messy eaters" that "constantly leak metabolic intermediates like methanol and formate" into the surrounding water. In turn, these chemicals are food for other species of bacteria.
This may all sound very peculiar, and in some ways it is. Movile is the only cave whose ecosystem is known to be supported in this way, and the only such ecosystem on land.
...The same cannot be said for the animals of the cave. Millions of years of isolation has transformed them.
Many are born without eyes, which would be useless in the dark. Almost all are translucent as they have lost pigment in their skin. Many also have extra-long appendages such as antennae to help them feel their way around in the darkness.
There are no flies in Movile Cave, but the spiders still spin webs. Small insects called springtails bounce into the air and get caught in the webs.
In 1996, researchers categorised the animals in the cave. They included 3 species of spider, a centipede, 4 species of isopod (the group that includes woodlice), a leech never seen anywhere else in the world, and an unusual-looking insect called a waterscorpion...
...The conditions in both places may well be similar to the primordial Earth. In our world's early years, the Sun's light was obscured by an atmosphere thick with carbon dioxide, methane and ammonia. It could be that the first living cells were similar to those found in Movile Cave.
Almost 30 years after its discovery, Movile Cave remains perhaps the most isolated ecosystem on the planet. It surely has many more secrets to give up. There are plenty more organisms buried in the cave's sediments, waiting to be identified, and they could help us understand some of our deepest questions about the nature of life.