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Comment by sandworm101 | Hacker News Reader

And there are carnivorous trees, even entire forests:

https://hakaimagazine.com/features/salmon-trees/

"up to 50 percent of the total nitrogen the trees use comes from salmon."

https://pacificwild.org/salmon-feed-forests/

"resident bears have been known to carry over 6,200 kg of salmon from the rivers to the woods, eating two thirds of the protein and leaving behind nearly 2,000 kg of salmon remains. Bears play a critical role in transporting nutrients from freshwater to the terrestrial environment, spreading the food source to other species and the forest floor. Decaying salmon carcasses are distributed everywhere post spawning, allowing nutrient rich soil to provide for the dense plant life of the rainforest"

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Something is "carnivorous" if it directly consumes the flesh (or other parts) of an animal - usually a living one that it kills (as we have a different name for those that consume only already dead animals - necrophages).

Feeding on nutrients from an animal that died and was then broken down by other beings into base elements in the same area as your roots doesn't qualify these trees in any way as either "carnivorous" nor even "necrophage". Carnivorous plants are those that trap and kill animals that they then directly digest, such as a venus fly trap. Those don't just benefit from animals dying around them and being consumed by bacteria - they have mechanisms that cause the death of the animal and then secrete substances that directly convert the animal into plant nutrients.

This is really interesting, but they're not carnivorous. The decaying salmon deposit nutrients in the soil. Carnivorous plants actually digest the insects directly for nutrients, usually because the soil is inhospitable.

Yeah, I think it's the absence of traits evolved to attract, trap, and digest salmon that are all missing here.

I got really excited for a carnivorous salmon-fishing tree there for a second. I could envision how roots might evolve to jut into the water, and develop some one-way geometry that fish get trapped in.

It depends on how much you look into the forest floor. Many trees in a mature forest actively poison the soil to reduce competition for nutrients. Look at a pacific coastal rain forest (or Star Wars' Endor) and you see big trees and an open forest floor. The big trees do not allow smaller/medium trees to get going.(Some of this is lack of sunlight, but also soil PH.) So a salmon-dependent tree could adapt to prevent other plants from getting ahold of salmon nutrients.

Similar to the nitrogen from salmon on the coasts, I have read about plants getting calcium from deer/elk/moose antlers. You would think it wasn't much but then you realize how depleted a forest can be of calcium. It can put a halt on plant growth. Migrating deer then become a significant source of calcium movement.

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