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Comment by londons_explore | Hacker News Reader

It's surprising to me how many creatures have eyes, yet how few can create light.

Creating light isn't awfully hard biologically - there are lots of reactions that can create (mostly monochromatic) light. Even humans make tiny yet detectable amounts of light as a side effect of some cellular level chemical reactions.

It does use quite a lot of energy, but illumination to levels similar to moonlight is still tiny compared to the energy budgets of most animals, even if the biological light-making process is pretty inefficient.

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Maybe more might if there wasn't a giant ball in the sky spraying photons.

I guess most living things put more energy into not being seen so they're not eaten

Some do it to invite the dinner.

A lot more to invite mating partners.

A profitable strategy only if it attracts a lot more prey than predators.

In the case of deep-sea predators, there appears to be less bigger consumptive biomass than consumable biomass at present.

Currently, it is probably more advantageous for some luminous predators there than the risk of being eaten. The optical perception organs are probably reaching an evolutionary dead end down there. Better eyesight isn't an option.

But everything is in flux, it just depends on the time frame. Magnetic field perception might be an option. Are there deep-sea predators that hunt by magnetic sense?

But it's still cheaper to attract the food than to track it in the dark.

How about auditive perception?

Is 'pinging' the prey an option?

Well, one would need some organ that could be converted to ping, which fishes don't have.

You might find electrolocation in fish interesting :)

https://en.wikipedia.org/wiki/Electroreception

Thanks for the hint.

I see, the midnight zone is much more diverse then I thought.

This remind me of the dark forest hypothesis.

That was my first thought as well

Make it a toggle

Regarding humans making light, is this what you're talking about? https://www.livescience.com/7799-strange-humans-glow-visible...

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