the root (no rank)
Eukaryota (domain)
Metazoa (kingdom)
Cnidaria (phylum)
Hydrozoa (class)
Hydroida (order)
Anthomedusae (suborder)
Hydridae (family)
Hydra (genus)
[hide inferior taxa]
Hydra attenuata (species)
Hydra littoralis (species)
Hydra magnipapillata (species)
Hydra oligactis (species)
Hydra sp. (species)
Hydra viridis (species)
Hydra vulgaris (species)