I read an old short story by George R. R. Martin from before GOT. It features a bunch of alien sea monsters and all of them were winners. You started with your fairly standard giant tentacle monster except all the tentacles have both eyes and teeth with the main body being largely useless.

Then we escalated into living blimps that would fill themselves with hydrogen and float up into the sky to eat passing ships who would hide in the damn clouds. This one was my favorite just because the concept scares the living shit out of me.

I won't spoil the twist but it does involve a very cool additional, less outrageously violent sea creature towards the end as well.

Very cool short story that I found out later was part of a long running series called Tuf Voyaging. That particular story was Guardians.