Daughters of Triton is the opening song in the movie The Little Mermaid, which aired in the US on November 17, 1989.
In the song, six of the King's daughters - Aquata, Andrina, Arista, Attina, Adella, and Alana - are shown introducing themselves in song form. Near the end, it is shown that the seventh daughter, the main character of the movie, Ariel, is scheduled to be introduced as she comes out of a clam shell, but since she wasn't there, the performance was cut short and the sisters were forced to end the song prematurely.
Ariel's sisters are surprised to find that she isn't in the clamshell.