Food webs are interaction networks that link predator and prey populations. The so-called functional response is the linking function that determines the uptake of prey by the predator. While it is clear that this function should be nonlinear and saturating with increasing prey densities, there is no single “right� function that describes the predator-prey interaction. A number of functions with vastly different mathematical properties (e.g., polynomial, exponential, trigonometric) are used in food web models. It has been shown previously that, already for two-species models, predictions about predator-prey dynamics and stability strongly depend on the choice of functional response. In this talk, I show the consequences of multiplying the sources of uncertainty by varying functional responses for the large number of predator-prey interactions that occur in complex food webs.