As is well-known to all who have read Hilchot Potter, Vol. 1-7, there are certain wizards who have managed to become animagi (singular: animagus), i.e., able to transform into animals (one animal per person).
I assume a Jew may not become a serpentine animagus (i.e., turn into a snake) because of לא תנחשו - Lo Tenachashu - You shall not become a snake. Does that mean that Jews may become other animals?