decapod vs decapod crustacean

decapod and decapod crustacean both are nouns.

Word	Noun	Adjective	Verb	Adverb
decapod	Yes	No	No	No
decapod crustacean	Yes	No	No	No

As nouns, decapod and decapod crustacean are synonyms defined as:

decapod and decapod crustacean: crustaceans characteristically having five pairs of locomotor appendages each joined to a segment of the thorax

decapod (noun)	decapod crustacean (noun)
crustaceans characteristically having five pairs of locomotor appendages each joined to a segment of the thorax	crustaceans characteristically having five pairs of locomotor appendages each joined to a segment of the thorax
cephalopods having eight short tentacles plus two long ones