costia vs flagellate protozoan

costia and flagellate protozoan both are nouns.

Word	Noun	Adjective	Verb	Adverb
costia	Yes	No	No	No
flagellate protozoan	Yes	No	No	No

As nouns, flagellate protozoan is a hypernym of costia; that is, flagellate protozoan is a word with a broader meaning than costia:

costia: a flagellate that is the cause of the frequently fatal fish disease costiasis
flagellate protozoan: a usually nonphotosynthetic free-living protozoan with whiplike appendages; some are pathogens of humans and other animals

Other hypernyms of costia include flagellate, flagellated protozoan, mastigophoran, mastigophore.

costia (noun)	flagellate protozoan (noun)
a flagellate that is the cause of the frequently fatal fish disease costiasis	a usually nonphotosynthetic free-living protozoan with whiplike appendages; some are pathogens of humans and other animals