Species
Hydra viridissima (Green hydra)
Hydra viridissima (also known as Hydra viridis and Chlorohydra viridissima), or the green hydra, is a species of freshwater hydroid polyp in the genus Hydra found widely dispersed in the northern temperate zone. It is a common organism found in still waters from early spring to late autumn. The characteristic green colour comes from cells of the unicellular alga Chlorella within the cells of the gastrodermis. Because of this, H. viridissima are generally less predacious than…