When she was later beheaded by the hero Perseus , Chrysaor and Pegasus emerged from her neck. There is also Triton , the merman ; Polyphemus , the cyclops ; and Oto and Ephialtae , the giants . Gill, N.S. (2007). "Mates and Children of Poseidon" . http://ancienthistory.about.com/cs/grecoromanmyth1/a/poseidonmates.htm . Retrieved on