  The magnetoelastic coupling in multiferroic $DyMn_2O_5$ is investigated by
magnetostriction measurements along the three crystallographic orientations.
Strong lattice anomalies as a function of the magnetic field are detected at
the low temperature magnetic and ferroelectric phase transitions. The sign and
magnitude of the magnetostrictive coefficient as well as the lattice anomalies
at the transitions are correlated with the Dy moment order and with the sharp
changes of the dielectric constant and the ferroelectric polarization. With the
magnetic field applied along the c-axis a new high-field phase has been
detected the magnetic structure of which has yet to be explored.
