There was an error published in J. Exp. Biol. 214, 3727-3731.

The funding information was incomplete. It should have read:

This work was supported by the European Commission (ICT-FET OCTOPUS Integrating Project, contract no. 231608) and by Istituto Banco di Napoli, Fondazione (Italy).

We apologise to authors and readers for any inconvenience this error may have caused.