Dependence between Volumes of Protoplast and Lorica in Lugol-fixed Tintinnid Ciliates

The relationship between the volume of tintinnid loricae and protoplasts was studied on the basis of bulk data derived from samples collected in a range of temperate environments: riverine, lacustrine, estuarine, and marine. All organisms were fixed with acid Lugol solution (0.5–1.0%). The dependence was described with the allometric equation: VL = 2.74 × VP1.03, where VL and VP are volumes [μm3] of loricae and protoplasts, respectively. The dependence was highly significant (p < 0.001, n = 417, R2 = 0.85). On average, protoplasts occupied 31% of the lorica volume. One species,Helicostomella subulata,was omitted from the calculations and treated separately since this ciliate has a relatively large lorica. The relationship identified between lorica and protoplast volumes permits recalculating incomplete data if protoplasts are the only body part measured.