pycnogonid vs arthropod

pycnogonid and arthropod both are nouns.

Word	Noun	Adjective	Verb	Adverb
pycnogonid	Yes	No	No	No
arthropod	Yes	No	No	No

As nouns, arthropod is a hypernym of pycnogonid; that is, arthropod is a word with a broader meaning than pycnogonid:

pycnogonid: any of various small spiderlike marine arthropods having small thin bodies and long slender legs
arthropod: invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin

pycnogonid (noun)	arthropod (noun)
any of various small spiderlike marine arthropods having small thin bodies and long slender legs	invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin