Acheilus

Sources identify Acheilus as a mortal son of Zeus who, after boasting about his beauty, was punished by a goddess and transformed into a shark. Theoi summarizes the motif: 'AKHEILOS (Acheilus) was a shark-formed sea daimon. He was once a handsome boy who was transformed into a shark by the goddess as punishment for boasting he was more beautiful she.' Other summaries (GreekLegendsAndMyths, Wikipedia) repeat that he is a son of Zeus and that the surviving account is a minor myth concerned with metamorphosis tied to hubris. The goddess who effects the change is not named in the cited sources.

The surviving sources characterize Acheilus primarily by the statement that he is 'shark-formed' and that he 'was once a handsome boy' prior to metamorphosis. Theoi explicitly calls him a 'shark-formed sea daimon.' No additional physical details (size, coloration, human-shark hybridity) are provided in the cited summaries; descriptions focus on the transformation from a handsome youth into a shark-shaped daimon.

The cited materials do not enumerate specific supernatural powers. Sources classify Acheilus as a 'sea daimon' and describe his origin by metamorphosis for hubris, but they do not specify active abilities such as speech, control of the sea, or particular interactions with humans in the surviving summaries. He is presented as a transformed marine daimonic figure rather than ascribed a catalogue of powers in the provided sources.