Plants normally suck up nitrogen, phosphorus and other goodies through their roots from soil. But in some places - peat bogs, swampy wetlands, leached rainforest cliffs - the soil is washed-out and almost nutrient-free. Plants that grow there have to find food some other way.
Carnivorous plants solved this by catching animals, mostly insects, and dissolving them for the nitrogen-rich proteins inside. They still make their own sugar through photosynthesis like any green plant - meat-eating just tops up the minerals they can’t get from the dirt.
What’s wild is that this meat-eating lifestyle evolved completely independently at least 12 times in totally different plant families. Venus flytraps, pitcher plants, sundews and bladderworts aren’t closely related; they each invented their own brutal traps for the same reason. Nature loves a good idea, apparently.
