Autotrophs: make their own organic molecules
| Photoautotrophs | Use light energy (as in photosynthesis) |
| Chemoautotrophs | Use energy obtained from inorganic substances (as in chemosynthesis) |
Heterotrophs: obtain carbon & energy from other organisms
| Parasites | Obtain energy from their hosts while living on or in their tissues |
| Decomposers | Obtain energy from dead, decaying matter |