I have heard the mermaids singing, each to each
I do not think that they will sing to me.
I have seen them riding seaweed on the waves
Combing the white hair of the waves blown back
We have lingered in the chambers of the sea
By sea-girls wreathed with seaweed red and brown
Till human voices wake us, and we drown.

This page was last updated: January 9, 2016
WELCOME TO THE WATERY WORLD                       OF MERMAIDS
A mermaid is a legendary aquatic creature with the head and torso of human female and the tail of a fish. The male version of a mermaid is called a merman; gender-neutral plurals could be merpeople or merfolk.
A marine creature with the head and upper body of a beautiful young maiden and with the lower body of a fish. She can be found in seas and lakes, or lying on a rock and combing her hair with one hand while holding a mirror in the other. Mermaids sometimes foretell the future and are often accompanied by seals.
According to myth, they lure sailors by singing and with lovely music. They live in a kingdom on the bottom of the sea, and it is here they take their prisoners to. From this story, the fear amongst the sailor grew and they thought that seeing a mermaid would cause bad luck: it could predict death by drowning. 
In Greek mythology, the Sirens are creatures with the head of a female and the body of a bird. They lived on an island (Sirenum scopuli; three small rocky islands) and with the irresistible charm of their song they lured mariners to their destruction on the rocks surrounding their island. 
According to myth, they lure sailors by singing and with lovely music. They live in a kingdom on the bottom of the sea, and it is here they take their prisoners to. From this story, the fear amongst the sailor grew and they thought that seeing a mermaid would cause bad luck: it could predict death by drowning. 
The Argonauts escaped them because when he heard their song, Orpheus immediately realized the peril they were in. He took out his lyre and sang a song so clear and ringing that it drowned the sound of those lovely fatal voices. When on another journey the Odysseus' ship passed the Sirens, had the sailors stuff their ears with wax. He had himself tied to the mast for he wanted to hear their beautiful voices. The Sirens sang when they approached, their words even more enticing than the melody. They would give knowledge to every man who came to them, they said, ripe wisdom and a quickening of the spirit. Odysseys' heart ran with longing but the ropes held him and the ship quickly sailed to safer waters.
The belief in mermaids is not limited to a few countries, but there are tales from all over the world (in India, for instance, there are the Apsara, beautiful water nymphs). However, most of those tales were told by sailors who "saw" them on their long journeys. The idea of mermaids and mermen, the male equivalent, could be based on creatures from Greek and Babylonian mythology: Sirens and Tritons of the Greeks, and the fish gods, who were half human and half fish, from the Babylonians. 
What manner of creature exists that being half human, which belongs on land, and half that is of the sea should call out to us in a song so sweet as to bring us to ruin upon these rocks. Beware least you too hear her songs and also be lost.

I sat upon a promontory,
And heard a mermaid, on a dolphin's back,
Uttering such dulcet and harmonious breath,
That the rude sea grew civil at her song;
 And certain stars shot madly from their spheres,
To hear the sea-maid's music.
       - William Shakespeare

Slow sail'd the weary mariners and saw,
Betwixt the green brink and the running foam,
Sweet faces, rounded arms, and bosoms prest
To little harps of gold; and while they mused
Whispering to each other half in fear,
Shrill music reach'd them on the middle sea.
       - Lord Alfred Tennyson-

Who would be
A mermaid fair,
Singing alone,
Combing her hair
Under the sea,
In a golden curl
With a comb of pearl,
On a throne?
I would be a mermaid fair;
I would sing to myself the whole of the day;
With a comb of pearl I would comb my hair;
And still as I comb I would sing and say,
 "Who is it loves me? who loves not me?"
       - Lord Alfred Tennyson