sea animal vs animate being

sea animal and animate being both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea animal	Yes	No	No	No
animate being	Yes	No	No	No

As nouns, animate being is a hypernym of sea animal; that is, animate being is a word with a broader meaning than sea animal:

sea animal: any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals
animate being: a living organism characterized by voluntary movement

Other hypernyms of sea animal include animal, beast, brute, creature, fauna.

sea animal (noun)	animate being (noun)
any of numerous animals inhabiting the sea including e.g. fishes and molluscs and many mammals	a living organism characterized by voluntary movement