In A Nutshell
Somewhere along the literary and mythological road, mermaids and sirens got confused into one creature: a half-woman, half-fish creature known for her beautiful singing voice. Originally, it was only the mermaid that was a half-human, half-fish creature, and a singing voice wasn’t mentioned in early myths. Sirens were the singers, and they were actually half-woman, half-bird creatures.
The Whole Bushel
In today’s pop culture world, the mermaid and the siren are often portrayed as the same character. They’re inevitably a beautiful woman from the waist up and a fish from the waist down, and they’re noted for their enchanting singing voices.
Originally, though, these two creatures were two entirely separate myths.
Mermaids have been in myths and folklore since their first appearance in ancient Babylonian stories. Era, the fish god, was half man and half fish; after that, it was the Greek god Triton. In fact, it was the Greeks who gave us the first descriptions of mermaids. Living specimens were said to have been examined by writers such as Pausanias in the second century, and were described as having scales covering their entire bodies, gills, a fish-like mouth, and a scaly tail like a dolphin’s.
It was the nereids of Greek mythology who gave rise to the tales of the mermaids that were so popular among later sailors’ mythology. These sea nymphs were given the features traditionally associated with the mermaid, half beautiful woman, half fish. These enchanting creatures were well known to mingle with humans and to bear children. The Greek hero Achilles was born of a mermaid, and some Greek families today still claim mermaid blood in their lineage. Nereids were found anywhere there was water, including springs and wells. While mermaids have always been enchanting, it’s been more their appearance than their singing voice.
It was the sirens that were known for their singing voices, supposedly of such beauty that sailors would forget what they were doing, and simply stop to listen. Ships would crash on the rocks around the sirens’ island, killing those who fell prey to their song.
But the sirens were never half-woman and half-fish creatures. Originally, there were only three sirens, and they started out as mortal human women who were the handmaidens of Persephone, daughter of the goddess Demeter. When Persephone was abducted by Hades, Demeter gifted the three girls with the bodies of birds so they could help search for the lost girl. When they couldn’t find her they eventually gave up and went to live on the island of Anthemoessa, cursed by Demeter (who was angry at their abandonment of the search) to remain in their half-bird form.
The sirens were further cursed when they entered a singing competition with the Muses and lost the contest as well as their wings and many of their feathers.
Eventually, the sirens died with the fulfillment of a prophecy that should anyone be able to resist their song, the sirens would perish. And they did; when Odysseus had his men block their ears and then tied himself to the mast of his ship so he could listen but not interfere, the sirens hurled themselves into the sea and died as he passed.
Sirens and mermaids have been confused for a long time, well before Piers Anthony and C.S. Lewis assigned mermaids their singing voices. Thomas Hoccleve’s “La Male Regle,” written in the 15th century, clearly refers to mermaids luring sailors to their death with their song. Strangely, it is this melding of the two creatures that has persisted throughout the centuries; according to sailors’ logs and records dating back to the 1600s, mermaids were very, very real. Although obviously debunked, the myth of the mermaid has continued, with some sightings being reported as late as 2009.
Show Me The Proof
Sirens: Bird-Women Monsters
Sea Monsters and Mermaids, Greek Myths and Legends, by Adrienne Mayor
LiveScience: Mermaids & Mermen: Facts & Legends
TV Tropes: Sirens are mermaids