Application of various depolarizing currents to barnacle muscle fibers produces spikes or oscillations for some values of the applied current. The Morris–Lescar model, which is a simplified version of the Hodgkin–Huxley model, involves a fast-activating calcium current; a slow potassium current, which is coupled to the calcium current; and a passive leak. The nonlinear simultaneous differential equations display bifurcation corresponding to these modes of behavior for various values of the relevant parameters.