The Goddess Parvati rides a tiger in her incarnation as "Durga or Shakti"(Power)as she is known in the form. The form was taken to kill the demons who were terrorizing the earth and heaven. The Lion (its actually Lion in ancient scriptures)came forward to be her vehicle in fighting the demons. Now in many photographs the Goddess is made to be seen riding the tiger. The Goddess when is on the Lion with its(Lion's) mouth open, it is the symbol of being in battlefield and if the mouth of Lion is closed it is peacetime. It is said that at home (for prayer) one should keep the one which has the mouth of Lion closed.

Alex