or chemolithoheterotroph . Evidence suggests that some fungi may also obtain energy from radiation. Such radiotrophic fungi were found growing inside a reactor of the Chernobyl nuclear power plant . Flowchart Autotroph Chemoautotroph Photoautotroph Heterotroph Chemoheterotroph Photoheterotroph Animal nutrition There are seven major classes of nutrient s: carbohydrates , fat s, fiber , minerals