  A simple dynamical cascade model for the evolution of free energy is
considered in the context of gyrokinetic formalism. It is noted that the
dynamics of free energy, that characterize plasma micro-turbulence in magnetic
fusion devices, exhibit a clear predator prey character. Various key features
of predatory prey dynamics such as the time delay between turbulence and large
scale flow structures, or the intermittency of the dynamics are identifed in
the quasi-steady state phase of the nonlinear gyrokinetic simulations. A novel
prediction on the ratio of turbulence amplitudes in different parts of the
wave-number domain that follows from this simple predator prey model is
compared to a set of nonlinear simulation results and is observed to hold quite
well in a large range of physical parameters. Detailed validation of the
predator prey hypothesis using nonlinear gyrokinetics provides a very important
input for the effort to apprehend plasma microturbulence, since the predator
prey idea can be used as a very effective intuitive tool for understanding.
