any freshwater or marine coelenterate of the class Hydrozoa, including free-swimming or attached types, as the hydra, in which one developmental stage, either the polyp or medusa, is absent, and colonial types, as the Portuguese man-of-war, in which both medusa and polyp stages are present in a single colony.
adj. 形容词 adjective
belonging or pertaining to the Hydrozoa.
更多hydrozoan例句
For one tiny hydrozoan creature from the coast of Italy, avoiding death is something that just, well, happens—over and over and over again.