Dynamic supersymmetries of differential equations are defined. The case of a liquid drop with quadrupole deformation coupled to a particle with j = 3/2 is shown as an example of a situation where the dynamic supersymmetry OSp(5/4) may occur. A special solution, called E(5/4), of interest in the spectroscopy of odd-even nuclei in the transitional region between spherical and gamma unstable is explicitly worked out.