numerous species

What Is Hydra Vulgaris? “Hydra”, in Greek “ὕδρα” means water snake, from “ὕδωρ”, water. Conversely, the term cnidarians and related cnidocytes and cnidocysts come from cnida “κνιδη”, meaning nettle. … To the group Hydra vulgaris belong numerous species and subspecies of uncertain distinction present in all the continents. What does the name Hydra vulgaris mean?