Tardigrades were sandwiched between cover glasses for observation. Polystyrene particles were sometimes used to maintain the distance between the glasses. The bright field and fluorescence images were obtained using an IX73 inverted microscope with a DP74 camera adapter (Evident (Olympus)). LUCPLFLN 20X PH and LUCPLFLN 40X PH lenses (Evident (Olympus)) were used. For observation of GCaMP6s and subcellular localization, a TCS SP8 confocal laser scanning microscope (Leica Microsystems) equipped with HC PL APO CS2 20×/0.75, HC PL APO CS2 63×/1.20, and HC PL APO CS2 100×/1.40 objectives (Leica Microsystems) was used. Images were analyzed with ImageJ2 and Fiji.