The Wonder Twins, Zan and Jayna, are a pair of shapeshifting sibling heroes on Super Friends.
To enable their powers, the twins touch their fists together while intoning, "Wonder Twin powers, activate!" Zan can then assume the form of water, steam or any ice construct, and Jayna can become whatever kind of animal is needed. To return to their default forms, they touch again and say, "Wonder Twin powers, deactivate!" Their pet monkey, Gleek, has a long prehensile tail.
Originally, the Wonder Twins were exclusive to the continuity of the Super Friends animated series and the Super Friends comic book adaptation, but they were later re-imagined for the modern Post-Crisis environment and introduced in the pages of Extreme Justice.
- Wonder Twins at the DC Comics Database Wiki