The Sirens depicted in various classical literature as the mythical creature with two forms: the appearance of half-woman half-bird, other sources said half-woman half-fish (mermaid), and with their magical song, they enchant the seafarer and fishermen. Every person who hears them singing will forgot everything and died of hunger. In the Age of Alexander (300 B.C.), it began to lose its bird shape, and by the Middle Ages, it was described as having a fish’s tail. By the end of the twelfth century, the Siren was considered synonymous with the mermaid. The myth of the sirens is one of the most enduring myths, among the sailors and seafarer it still exists even into the present day. Sources of classical literature about the Sirens can be found in Aristotle, Pliny, Ovid, Hyginus, Physiologus (2nd century A.D.) and medieval bestiaries.
In Greek mythology, the Sirens (the mermaid form) were the daughters of Phorcys, a Greek god of the sea. While the bird form, they were supposed to be daughters of the river Achelous by the nymph Calliope; and Ceres turned them into birds.
According to Homer (9th century B.C.), they were lived on an island between Aeaea, the Circe's home and the Scylla’s lair. Sirens, who once lived in a forest, near a rivebank, issued a challenge to the Muses in a singing duel, but sirens lost the challenge, whereupon they leaving their forest habitat, and took refuge on the rocky coast in southern Italy. Here they spent days so they could entice the wayfarer, only to devour them. This is where Odysseus encounter the Sirens.Several days before his encounter, Circe magical powers turned Odysseus' men into swine when they landed on Aeaea on their way home from Troy. Aided by Hermes, the messenger god, Odysseus was immune to Circe's magic and restored his crew to human form, and also gained the witch's aid for the next part of his joumey For a year he stayed as her lover, before she told him how to navigate through the waters of the Sirens and between Scylla, a monster, and Charybdis, a whirlpool. Scylla had been a rival of Circe, who had turned her into a monster when one of her many lovers had shown an interest in the unfortunate girl.
Circe had warned of the dangers caused by these creatures, urging Odysseus to close his men ears with wax after ordered him to bind his body with the strong rope to the mast of his ship. These men are allowed concentrate on rowing at the same time makes them immune to their magical song.
Odysseus and the Sirens (bird form), eponymous vase of the Siren Painter, ca. 480-470 BC
On the tympanum of the chapel of St. Michael d’Aiguilhe at Le Puy, the statue of the two-tailed sirens are dating from before the 10th century, and the siren-birds statue can be seen at Saint-Benoît-sur-Loire.
The two-tailed sirens
They may well be representations of the inferior forces in woman; or they could also be symbolic of the corrupt imagination enticed towards base ends or towards the primitive strata of life; or of the torment of desire leading to self-destruction, for their abnormal bodies cannot satisfy the passions that are aroused by their enchanting music and by their beauty of face and bosom. It seems that they are largely symbols of the ‘temptations’ scattered along the path of life (or of symbolic navigation) impeding the evolution of the spirit by bewitchment, beguiling it into remaining on the magic island; or, in other words, causing its premature death.
A Dictionary of Symbols by J. E. Cirlot;
Mysterious Creatures: “A Guide to Cryptozoology” by George M. Eberhart;
Seafaring, Lore & Legend: “A Miscellany of Maritime Myth, Superstition, Fable, and Fact by Peter D. Jeans;
The Encyclopedia of Mythology by Arthur Cotterell
A Dictionary of Symbols by J. E. Cirlot page 297