Sentence:  Typically, what we think of as the jellyfish, the <WSD>medusa</WSD>, reproduces sexually, spawning sperm and eggs which, once fertilised, turn into sea anemone-like polyps, which attach themselves to the jellyfish's bottom or other surfaces. 
Meaning of the word marked with <WSD> tags:  A jellyfish; specifically , a non-polyp form of individual cnidarians, consisting of a gelatinous umbrella-shaped bell and trailing tentacles. (from 18th c.)