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How do animals obtain nitrogen from plants and other organisms?

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Difference in molecular structure between ammonia/amines and quaternary ammonium ions — ammonia Ammonia and amines have a slightly flattened trigonal pyramidal shape with a lone pair of electrons above the nitrogen. In quaternary ammonium ions, this area is occupied by a fourth substituent.

Animals obtain nitrogen by consuming plants or other organisms that have already assimilated nitrogen-based compounds into their tissues.12

While nitrogen is abundant in the atmosphere, most living organisms cannot utilize it in its gaseous form. Instead, they rely on nitrogen fixation—a process primarily performed by bacteria and blue-green algae—to convert atmospheric nitrogen into reactive compounds like ammonia and nitrates. These compounds are absorbed by plants and algae, which incorporate them into their own tissues.13

When animals ingest these plants or other organisms, they take in these nitrogenous compounds and convert them into their own body compounds, such as proteins and nucleic acids. Nitrogen that is not used for growth or maintenance is eventually excreted as waste products, such as urea or ammonia, which are then recycled back into the environment by microorganisms.32145