sea animal vs marine animal

sea animal and marine animal both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea animal	Yes	No	No	No
marine animal	Yes	No	No	No

As nouns, sea animal and marine animal are synonyms defined as:

sea animal and marine animal: any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals

Other synonyms of sea animal include marine creature, sea creature.

sea animal (noun)	marine animal (noun)
any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals	any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals