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69 points wglb | 2 comments | | HN request time: 0.42s | source
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usrusr ◴[] No.42481539[source]
Predator sounds dramatic, but there really isn't much non-microscopic life in the oceans that isn't predatorial. Large herbivores are land-evolved.
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1. adrian_b ◴[] No.42482114[source]
While there are no herbivores there, many animals at that depth are suspension feeders or deposit feeders, i.e. they filter the water or the mud for either alive micro-organisms or for organic substances that come from the decomposition of dead animals or algae.

At that depth an important food source is formed by the dead bodies or parts of bodies of various big or small animals, which fall from shallower water after their death.

Because at high depths there is no primary production in most places (with the exception of vents where free dihydrogen or dihydrogen sulfide may feed bacteria), most animals must eat the dead organic matter that falls from above.

Predators that eat alive animals from that depth must be much fewer than the animals which eat dead matter, otherwise they will die of hunger.

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2. usrusr ◴[] No.42485378[source]
Suspension feeders/deposit feeders, thanks that makes a lot of sense: the local food chain does need some base, that base can't be solar powered as there really isn't enough light down there. Some scraps from the solar-powered layers making it down all the way because of gravity, that's a logical explanation to have any life down there at all.

Tangent: makes me wonder if fossil fuel depots that accumulated under the oceans might have a similar "they don't make them anyone as they used to" as the lignin/fungus imbalance of the carboniferous (I know that there are studies questioning that link, or at least suggesting that this can't be the whole story): before those feeders evolved, there would have been undisputed accumulation, and the first few evolutionary matches might have died out after burning through deposits in waves of overpopulation and extinction, before stochastics hit a stable balance. But, well, I'm just a speculation layman, experts will still have enough uncertainty for a wide range of speculation (see the wide range of uncertainty in the lignin hypothesis, and I'd assume that our knowledge of land biohistory is far more detailed than what we know about the oceans), lots of science to be done!