Species classify as groups of organisms that can interbreed to produce fertile offspring.
Autotrophs obtain inorganic nutrients from the abiotic environment. This means they are the producers of their own food.
Heterotrophs in contrast, are consumers of food they did not produce themselves.
Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
Example: earth worms
Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.