00:00We normally assume every food web on Earth requires sunlight to survive.
00:04But a process called chemo-autotrophy powers extreme life in complete darkness.
00:09How does it work?
00:11Take Antarctica's Blood Falls, an underground saltwater lake sealed beneath the ice for 5 million years.
00:18Beneath the Taylor Glacier lies a trapped layer of liquid brine, scraping against iron-rich bedrock.
00:24This water is completely cut off from solar energy, and it is entirely devoid of oxygen.
00:30Yet microbes thrive here by physically interacting with the stone itself.
00:35Instead of catching photons from the sun, they extract chemical energy directly from the minerals.
00:40These bacteria strip electrons from the abundant sulfur and iron compounds in the rock,
00:45driving their internal metabolism by effectively breathing iron instead of oxygen.
00:49By harvesting this energy, the bacteria can build brand new organic carbon completely from scratch.
00:55This mineral-based primary production sustains a totally independent food web in the absolute dark.
01:01So, if they are completely buried in the dark, what about that striking red waterfall at the surface?
01:08That red color is simply the rusted iron waste left behind by an entire underground world of rock-eating microbes.
