Kuroimaken, Fluffles, thank you.
edit: although, excuse me for my being slow to understand, but in the SRD entry for Polymorph I read: "It also gains all extraordinary special attacks possessed by the form but does not gain the extraordinary special qualities possessed by the new form or any supernatural or spell-like abilities. ".
Now, for example, a Beholder's eye rays are listed as Su, and even if I couldn't find a descriptor for a Pyro\Cryohydra's special attacks, they seem to be a breath weapon, which defaults to Su if not stated otherwise. How do you get those?!