Hydridae Dana, 1846
Hydra baikalensis Swarczewski, 1923
Hydra beijingensis Fan, 2003
Hydra brunnea Templeton, 1836
Hydra canadensis Rowan, 1930
Hydra cauliculata Hyman, 1938
Hydra circumcincta Schulze, 1914
Hydra daqingensis Fan, 2000
Hydra ethiopiae Hickson, 1930
Hydra hadleyi (Forrest, 1959)
Hydra harbinensis Fan & Shi, 2003
Hydra hexactinella von Lendenfeld, 1886
Hydra hymanae Hadley & Forrest, 1949
Hydra iheringi Cordero, 1939
Hydra intaba Ewer, 1948
Hydra intermedia De Carvalho Wolle, 1978
Hydra japonica Ito, 1947
Hydra javanica Schulze, 1927
Hydra liriosoma Campbell, 1987
Hydra madagascariensis Campbell, 1999
Hydra magellanica Schulze, 1927
Hydra mariana Cox & Young, 1973
Hydra minima Forrest, 1963
Hydra mohensis Fan & Shi, 1999
Hydra oligactis Pallas, 1766
Hydra oregona Griffin & Peters, 1939
Hydra orientalis Annandale, 1905
Hydra oxycnida Schulze, 1914
Hydra paludicola Ito, 1947
Hydra paranensis Cernosvitov, 1935
Hydra parva Ito, 1947
Hydra plagiodesmica Dioni, 1968
Hydra polymorpha Chen & Wang, 2008
Hydra robusta (Ito, 1947)
Hydra rubra Lewes, 1860
Hydra rutgerensis Forrest, 1963
Hydra rutgersensis Forrest, 1963
Hydra salmacidis Lang da Silveira, Souza-Gomes & de Souza e Silva, 1997
Hydra sinensis Wang, Deng, Lai & Li, 2009
Hydra tenuis Ayres, 1856
Hydra thomseni Cordero, 1941
Hydra umfula Ewer, 1948
Hydra utahensis Hyman, 1931
Hydra verrucosa Templeton, 1836
Hydra viridissima Pallas, 1766
Hydra vulgaris Pallas, 1766
Hydra zeylandica Burt, 1929
Hydra zhujiangensis Liu & Wang, 2010
Pelmatohydra baikalensis (Swarczewski, 1923)
