hydra
/ˈhaɪdrə/noun
1- a minute freshwater coelenterate with a stalk-like tubular body and a ring of tentacles around the mouth水螅。
1.1
- Genus Hydra, class Hydrozoa.水螅属, 水螅虫纲。
词源
via Latin from Greek hudra 'water snake' （see HYDRA）, named by Linnaeus because, if cut into pieces, each section can grow into a whole animal.