sagitta vs arrowworm

sagitta and arrowworm both are nouns.

Word	Noun	Adjective	Verb	Adverb
sagitta	Yes	No	No	No
arrowworm	Yes	No	No	No

As nouns, arrowworm is a hypernym of sagitta; that is, arrowworm is a word with a broader meaning than sagitta:

sagitta: any arrowworm of the genus Sagitta
arrowworm: any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth

Other hypernyms of sagitta include chaetognath.

sagitta (noun)	arrowworm (noun)
any arrowworm of the genus Sagitta	any worm of the Chaetognatha; transparent marine worm with horizontal lateral and caudal fins and a row of movable curved spines at each side of the mouth