  Based on integral field spectroscopy data from the CALIFA survey, we
investigate the possible dependence of spiral arm pitch angle with optical
wavelength. For three of the five studied objects, the pitch angle gradually
increases at longer wavelengths. This is not the case for two objects where the
pitch angle remains constant. This result is confirmed by the analysis of SDSS
data. We discuss the possible physical mechanisms to explain this phenomenon,
as well as the implications of the results.
