Fig. 4. Effects of fluid shear on fertilization success. Egg concentration was held constant (10³ cells ml^–1), and three sperm concentrations were assayed in separate tests (see text for details). Fertilization is described as a function of log-shear, using least-squares regression to identify the best fits (10⁶ sperm ml^–1: y=83–7log₁₀(x), r²=0.76, F_1,83=166.1, P<0.001; 10⁵ sperm ml^–1: y=42.6–12.2log₁₀(x), r²=0.81, F_1,88=151.7, P<0.001; 10⁴ sperm ml^–1: y=17.9–5.7log₁₀(x), r²=0.80, F_1,87=157.7, P<0.001). Each symbol is a mean ± s.e.m.; error bars are smaller than symbol sizes in some cases.