Relatively speaking? I think Cephalopods are smarter than humans, with their life span of 3 - 5 years their cognitive intelligence I think meets or exceeds most toddlers.

They decide to die by starvation after laying eggs and the majority of the babies are killed while they are defenseless.

With any organization and cognition that they don't have to die at this point in their life, they could perhaps take over the ocean.