Hydra(redirected from Hydra (disambiguation))
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Hydraa genus of the coelenterate class Hydrozoa. Most species are found in freshwater, and are unusual members of the Hydrozoa in not having an ALTERNATION OF GENERATIONS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005