There was an error published in J. Exp. Biol. (2018) 221, jeb176750 (doi:10.1242/jeb.176750).

In Figs 6–10, the vorticity magnitude colour bar was incorrect. The original bar (left) and corrected bar (right) appear below.

Both the online full-text and PDF versions have been updated.

The authors apologise for these errors and any inconvenience they may have caused.