Figure 3.

The growth rate of uninfected and infected snails. (a) Relationship between growth rate and shell width in uninfected B. cumingi snails and in those infected by the trematode, C. batillariae. The data are shown as logarithmic dot-plots. The regression lines were calculated with linear regression on raw data for infected and uninfected snails. (b) Examples of marked shells of uninfected (left) and infected (right) snails (scale bar, 1 cm). The snail on the left shows the thickened lip of the aperture (varix) indicating cessation of rapid growth in an uninfected snail. The snail on the right, infected by C. batillariae, exhibits gigantism, rapid growth beyond the varix. The arrow indicates the varix (old maturation point) of the infected snail.