How do scientists know there’s life down there?

While we’re at sea, we’ve got this great group of scientists all together in the same place. Each one knows a little something different, so they all get together and teach each other about what they know. Yesterday, I got learn from Dr. Olivier Rouxel, a Petrologist from France. He taught us about some of the chemical reactions that happen way down in the ocean crust, and he also told us about deep biosphere—a system of living things deep below the surface of the ocean floor.

microbial activity seen in core samples

The deep biosphere is far away and hard to get to, so how do scientists know there’s life down in the rocks below the seafloor? First, they found some shapes and textures in the rocks that couldn’t be explained by the physical or geochemical processes they knew about. Then, they found some chemical signatures in the rocks that indicated that microbes might be eating them. Finally, they found some DNA evidence that shows that there are microorganisms living in the fluids deep down in the ocean crust.

microbial tubules

It’s amazing what scientists can learn from the samples of sediment, rocks, and water from the ocean crust!


Have you found evidence of

Have you found evidence of microbial activity in the rocks in the cores brought up during this expedition?
What unexpected or unusual evidence has shown up in the cores? from St Ursula Academy Geoscience Class, Toledo, Ohio