According to Pethig and Tschirhart (2002), the micro approach uses individual organisms
as the basic units of analysis. The representative organisms are assumed to maximize
their net energy, biomass, reproduction, and
avoidance of predation as price takers subject to appropriate
constraints (Tschirhart 2000; Pethig & Tschirhart
2002; Eichner & Pethig 2006; Ravn-Jonsen 2009). The
organisms behave as consumers who face a budget constraint
requiring that their expenditure on prey biomass
not exceed their revenue from supplying their own biomass (Eichner & Pethig 2006).