kamo means duck in japanese, but it also means "maybe" i think..
maybe he has a duck form too, but still a seahorse

here's some about kamo..
he is a little ditzy and eccentric. however, he does have a sharp eye and says whatever's on his mind at the moment, coming off as blunt but in a playful or oblivious way, not like little my
he is also laid-back but energetic most the time and cheerful in almost any situation. kamo means well most of the time even when being blunt, and shows interest in music, mostly the flute
he is also loyal, especially to his older brother and sister. he is still very curious about the world, as he's mostly been underwater (as seahorse and magical human)

he's a little older and taller than darci, so he's more 'mature'.
the reason why they look similar is unknown
he's more of a teenager