Hydra (genus)

Hydra
	Hydra budding
Scientific classification
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Hydrozoa
Order:	Anthoathecata
Family:	Hydridae; Dana, 1846
Genus:	Hydra; Linnaeus, 1758
Species
	List * Hydra baikalensis Swarczewsky, 1923 ; * Hydra beijingensis Fan, 2003 ; * 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 hymanae Hadley & Forrest, 1949 ; * Hydra iheringi Cordero, 1939 ; * Hydra intaba Ewer, 1948 ; * Hydra intermedia De Carvalho Wolle, 1978 ; * Hydra japonica Itô, 1947 ; * Hydra javanica Schulze, 1929 ; * 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 oxycnida Schulze, 1914 ; * Hydra paludicola Itô, 1947 ; * Hydra paranensis Cernosvitov, 1935 ; * Hydra parva Itô, 1947 ; * Hydra plagiodesmica Dioni, 1968 ; * Hydra polymorpha Chen & Wang, 2008 ; * Hydra robusta (Itô, 1947) ; * Hydra rutgersensis Forrest, 1963 ; * Hydra salmacidis Lang da Silveira et al., 1997 ; * Hydra sinensis Wang et al., 2009 ; * Hydra thomseni Cordero, 1941 ; * Hydra umfula Ewer, 1948 ; * Hydra utahensis Hyman, 1931 ; * Hydra viridissima Pallas, 1766 ; * Hydra vulgaris Pallas, 1766 ; * Hydra zeylandica Burt, 1929 ; * Hydra zhujiangensis Liu & Wang, 2010;
Synonyms
	Chlorohydra;

Hydra (/ˈhaɪdrə/ HY-drə) is a genus of small freshwater hydrozoans in the phylum Cnidaria. They are solitary, carnivorous jellyfish-like animals, native to the temperate and tropical regions. The genus was named by Linnaeus in 1758 after the Hydra, the mythical many-headed beast that was defeated by Heracles, as when the animal has a part severed, it will regenerate much like the mythical Hydra's heads. Biologists are especially interested in Hydra because of their regenerative ability; they do not appear to die of old age, or to age at all.