Hydra and Obelia are two genera of small aquatic animals of the phylum Cnidaria, class Hydrozoa. What is Hydra? Hydra is a genus of small diploblastic freshwater animals from the class Hydrozoa. The representatives of the genus are up&hellip

Hydra and Obelia are two genera of small aquatic animals of the phylum Cnidaria, class Hydrozoa. What is Hydra? Hydra is a genus of small diploblastic freshwater animals from the class Hydrozoa. The representatives of the genus are up&hellip