7. Of Anthedon in Boeotia, a fisherman, who had the good luck to eat a part of the divine herb which Cronos had sown, and which made Glaucus immortal. (Ath. 7.295; Claud. de Nupt. Mar. 10.158.) His parentage is different in the different traditions, which are enumerated by Athenaeus; some called his father Copeus, others Polybus, the husband of Euboea, and others again Anthedon or Poseidon. He was further said to have been a clever diver, to have built the ship Argo, and to have accompanied the Argonauts as their steersman. In the sea-fight of Jason against the Tyrrhenians, Glaucus alone remained unhurt; he sank to the bottom of the sea, where he was visible to none save to Jason. From this moment he became a marine deity, and was of service to the Argonauts. The story of his sinking or leaping into the sea was variously modified in the different traditions. (Bekker, Anecdot. p. 347; Schol. ad Plat. de Leg. x. p. 611.) There was a belief in Greece that once in every year Glaucus visited all the coasts and islands, accompanied by marine monsters, and gave his prophecies. (Paus. 9.22.6.) Fishermen and sailors paid particular reverence to him, and watched his oracles, which were believed to be very trustworthy. The story of his various loves seems to have been a favourite subject with the ancient poets, and many of his l06e adventures are related by various writers. The place of his abode varies in the different traditions, but Aristotle stated that he dwelt in Delos, where, in conjunction with the nymphs, he gave oracles; for his prophetic power was said by some to be even greater than that of Apollo, who is called his disciple in it. (Schol. ad Apollon. Rhod. 1.1310; Tzetz. ad Lycoph. 753; Eustath. ad Hom. p. 271; Ov. Met. 13.904, &c.; Serv. ad Virg. Georg. 1.437, Aen. 3.420, 5.832, 6.36; Strab. p. 405.) A representation of Glaucus is described by Philostratus (Imag 1.15): he was seen as a man whose hair and beard were dripping with water, with bristly eye-brows, his breast covered with sea-weeds, and the lower part of the body ending in the tail of a fish. (For further descriptions of his appearance, see Nonn. Dionys. 13.73, 35.73, 39.99; Schol. ad Eurip. Orest. 318, 364 ; Stat. Silv. 3.2, 36, Theb. 7.335, &c.; Vell. 2.83.) This deified Glaucus was likewise chosen by the Greek poets as the subject of dramatic compositions (Welcker, Die Aeschyl. Trilogie, pp. 311, &c., 471, &c., Nachtrag, p. 176, &c.), and we know from Velleius Paterculus that the mimus Plancus represented this marine daemon on the stage.
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890