The Sun is the ultimate energy source for our planet. We need it for warmth and photosynthesis (and lots of other stuff.) Life would definitely not exist as we know it without either of those. Eg: without photosynthesis, bacteria would quickly (on a geologic scale) consume/turn to waste anything valuable (including oxygen). Without warmth, or planet would be too cold to sustain life.

We get our oxygen mostly from photosynthesis as well as a few other smaller sources (methane based, I think.)

Turns out, seasons help much of life on Earth too which is just defined by the tilt angle as it processes around the Sun.

Additionally, stars are factories for creating heavier elements. We wouldn’t have many of the requisite elements for life on Earth without them having been produced by the Sun first.

Plants (or more generally, photosynthetic life) are the most direct consumer of solar energy and thus the most abundant source of energy for other living organisms on the planet.

Makes me wonder if anyone made a chart of various organisms depicted as ranges on a "degree of energy separation from sunlight", where plants are 0 (they eat sunlight), herbivores are 1 (they eat plants, which eat sunlight), etc.

These are called trophic levels https://en.m.wikipedia.org/wiki/Trophic_level

D'oh! Thanks, I completely forgot that this is literally what makes a food chain a food chain.

Hmm, if you had a species of vultures that only fed on apex predators would that give them a higher trophic level? Or what about bacteria that only eat human flesh? It's wild to think of a bacteria at the top of the chain. Does it count if you only partially eat the victim and don't kill them?

Deep sea vent organisms can extract energy from the nutrients and heat from the geothermal vents.

Yeah, life is messy. It’s part of why it is so hard to define what a living thing is. I think of the world as a giant soup of stuff that eats each other. It’s strange to me that humans think they are above any of it. Really, we are right in the middle of it all! :)

If I want to get super-reductive, I think of life as one continuous self-sustaining chemical reaction. It's an accurate, though usually not very useful way of thinking - but I still cherish it, as it reminds me that life and evolution do not obey the conceptual boundaries we set for it. The concept of a "cell" or "individual" doesn't exist in the runtime of physical reality - if we see evolution as optimization process, it's one that can and does optimize across those boundaries.

The weird fish and spiders in caves? And the creatures around volcanic vents?

There are a small number of organisms that get their energy ultimately from mineral sources and a few cases of an organism getting some energy from something similar to photosynthesis from local radioactive sources but the vast majority of energy used by living things by a wide margin comes from solar radiation.

Unless your food chain contains a significant number of extremophiles (like something eating near hydrothermal vents), essentially everything can be traced back to photosynthesis.

Seaweed is an algae, not a plant, as an edible counter example.

I put up war time Germany's coal butter up. Synthetic and could just add well be from scrubbed CO2 and electrolyzed hydrogen, instead of coal and water, as the feedstock/syngas source.

Thanks, I found this interesting read: https://www.sciencehistory.org/distillations/brave-new-butte...