The way I heard it, Tzvi means ‘deer,’ ‘stag’ (hence the double name Tzvi Hirsch) and is a variant of or reference to Naftali whose emblem was the deer. In the same way Binyomin lies behind the names Ze’ev and Wolf, since Binyomin’s sign was the wolf, and Ari/Aryeh/Ariel/Loeb are variants of Yehudah, the lion.
