291 words • 2~2 min read

Ocean of Pseudoscience Shorty – Chemosynthetic ecosystems and independence from the sun

One of the many frequent claims that crop up in both popular and scientific reports about deep-sea hydrothermal vents is that chemosynthetic ecosystems are independent of photosynthetic ecosystems. Even high quality scientific reporting have been guilty of making this claim: “These animals live completely independent of sunlight” (NOAA Ocean Explorer).

But are chemosynthetic systems totally independent of the sun?

Recall the basic equation for chemosynthesis:

CO2 + O2 + 4H2S -> CH20 + 4S + 3H2O

Now, this is a basic chemosynthesis reaction using hydrogen sulfide as the electron donor, this is not the only possible chemical pathway for chemosynthesis. Notice that one of the required molecules is O2. Where did that oxygen come from? Photosynthesis!

So while chemosynthetic ecosystems are not directly dependent on the sun for energy, a critical part of the chemosynthetic pathways requires a byproduct of photosynthesis, therefore, it is inaccurate to state that “These animals live completely independent of sunlight”

~Southern Fried Scientist


Deep-sea biologist, population/conservation geneticist, backyard farm advocate. The deep sea is Earth's last great wilderness.


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