OOHH fun question. these aren't my choices of representative animals but more how i see them:
heeseung: a cute little deer mouse...
jay: lately i've been enjoying calling him my little stingray in my head :3 i'm playing around with the idea of him as a black tarantula too awawawww
jake: this man is a dog hybrid.
sunghoon: i can't think of an animal that suits him tbh. out of the fan favourites i like bunny the most but there's something unsatisfying about it... the happiest i can be with is an otter which is really cute actually wait
sunoo: fennec fox so cutie so snarky
jungwon: MONKIII
ni-ki: i'm obsessed with how he always vandalises duck plushies and adds spots to them so we kinda need to continue with that forever but in my heart he's a snow leopard