doliolum vs urochord

doliolum and urochord both are nouns.

Word	Noun	Adjective	Verb	Adverb
doliolum	Yes	No	No	No
urochord	Yes	No	No	No

As nouns, urochord is a hypernym of doliolum; that is, urochord is a word with a broader meaning than doliolum:

doliolum: free-swimming oceanic tunicate with a barrel-shaped transparent body
urochord: primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva

Other hypernyms of doliolum include tunicate, urochordate.

doliolum (noun)	urochord (noun)
free-swimming oceanic tunicate with a barrel-shaped transparent body	a notochord of a larval tunicate typically confined to the caudal region
	primitive marine animal having a saclike unsegmented body and a urochord that is conspicuous in the larva