As polymorph other, except the character polymorphs up to one willing creature per level into an animal of the character's choice; the spell has no effect on unwilling creatures. Recipients remain in the animal form until the spell expires or the character dismisses the spell for all recipients. In addition, an individual subject may choose to resume her normal form (as a full-round action); doing so ends the spell for her and her alone.
The allowed size of the animal form depends on the character's level:
Caster Level Allowed Sizes ------------ -------------
Up to 16th Small or Medium-size 17th-19th Tiny through Large 20th Diminutive through Huge
Creatures polymorphed by this spell don't suffer the disorientation penalty that those transformed by polymorph other often do.