Objective: Members of the phylum Tardigrada can tolerate extended periods of complete dehydration. Surviving the anhydrobiotic state may be promoted by free floating storage cells, inhabiting the body cavity of all tardigrades. The purpose of the present study was to explore the electrophysiological properties of storage cells by investigating the occurrence of ion channels in the plasma membrane. Methods: Native storage cells isolated from the anhydrobiotic eutardigrade Richtersius coronifer were used for patch clamp studies in the cell- attached and the whole-cell configuration. Results: In the cell-attached configuration the most often encountered ion channel had a linear i/V-relationship with a reversal potential (V_rev) of 0.4 mV (n>=6). Single-channel conductance was estimated to 82.4±0.0 pS (mean±SE, n>=6). Binomial analysis of patches with 2-4 active channels showed that channels open and close stochastically. The open- state probability increased linearly with pipette potential. The whole-cell configuration showed an outwardly rectifying i/V-relationship with a V_rev of -18.2±1.1 mV (mean±SE, n=24). V_rev of the whole-cell current was closest to the equilibrium potential of Cl^-. Perfusion with Na-gluconate Ringer right-shifted V_rev from - 19.5±1.9 to 4.6±1.3 mV, and the outward current decreased significantly (mean±SE, n=5). Perfusion with KCl Ringer (n>=5) and addition of BaCl₂ (n=7) did not affect V_rev. Conclusion: Cell- attached patch clamp indicated a rather large, voltage-gated Cl^- channel. Whole-cell patch clamp indicated that macroscopic currents are mainly conducted by Cl^- channels. Perfusion with KCl Ringer and addition of BaCl₂ confirmed that a significant part of the whole-cell current is attributed to Cl^- channels. This is the first patch clamp study of tardigrade ion channel properties, and future studies are needed to firmly establish the identity and function of the channel.