Hydra Green

Hydra are small aquatic invertebrates belonging to the order Hydroida, in the class Hydrozoa, phylum Cnidaria.

This is the same phylum as the marine jellyfishes, corals, and sea anemones. Only a few species that belong to this phylum occur in freshwater due to the fact that they evolved in the sea. The body is a thin cylinder with several tentacles extending from the mouth (Five to seven tentacles are typical).

Hydra mainly feed on small aquatic invertebrates such as Daphnia and Cyclops. Some species of hydra exist in a symbiotic relationship with various types of green algae. The hydra offers the algae protection from predators and in return, the algae uses photosynthesis to give the hydra a food source.