Figure 1.

The counterbend phenomenon and geometry of deformation: (a) Micrograph showing the static configuration of a sea urchin sperm rendered passive with its head attached to the coverslip while forced externally by a microprobe [33], together with the geometrically exact filament-bundle model prediction. Red curve shows the model curve fitting result from Gadêlha et al. [34]. (b) Two-dimensional representation of the axoneme and the sliding filament mechanism with basal compliance [7,34–36]. Micrograph adapted from Gadêlha et al. [34]. (Online version in colour.)