Jellyfish stinging capsules known as nematocysts are explosive, natural-injection systems with high potential as a drug-delivery platform. These organelles consist of a capsule containing a highly folded thin needle-like tubule and a matrix highly concentrated with charged constituents that enable the tubule to fire and penetrate a target. Here, the nematocysts’ dielectric properties were experimentally investigated using dielectrophoretic and electrorotational spectra with best fits derived from theoretical models. The dielectric characterization adds to our understanding of the nematocysts’ structure and function and is necessary for dielectrophoretic isolation and manipulation of the populations. As expected, the effect of monovalent and divalent exchange cations resulted in higher inner conductivity for the NaCl treated capsules, in agreement with their relative higher osmotic pressure. In addition, an efficient dielectrophoretic isolation of different nematocyst sub-populations was demonstrated, paving the way to an understanding of nematocysts’ functional diversity and the development of an efficient drug delivery platform.