Triton

In Greek mythology, Triton was originally a sea god with the torso of a man and the tail of a fish. He was the son of the sea god Poseidon and the sea nymph Amphitrite, and ruled the waters together with some of his brothers.

Poseidon also had some creatures called Tritons: they, too, were half fish with human torsos, and were lower than his son Triton. The females of the species are known as Nereids, sometimes also called Tritonesses. The Tritons flitted across the waves and blew on conches, which they used as horns. They were alternately depicted as human sea creatures, or as sea centaurs: half man, half horse.