The process of taking food and utilising it to produce energy in the organism to do daily task is called nutrition. Nutrition are of two types for autotrophic and heterotrophic nutrition. Hetrotrophic nutrition is what is obtained from other element in the environment. The heterotrophic organisms do not perform photosynthesis so they are not capable of making their own food. Except for plants all the other living organisms hetrotrophic so thats why they have large number of different spicies of organism in it, so it is divided into subcategories from which one is saprotrophic nutrition.
Saprotrophic nutrition is that nutrition in which an organism obtain its nutrition from decaying organic matter of decaying plants and animals. Example fungi, mushroom, yeast. These organisms are called saprotrophs.