The Sirens

The Sirens are mythical creatures  who appeared in the  DuckTales  episode " Home Sweet Homer ".

Home Sweet Homer
Scrooge McDuck, his nephews, and Prince Homer were riding on their new yacht when Homer realizes that they are nearing the island of the sirens, warning that they must cover their ears and not hear them singing. Scrooge was unaware of their hypnotic powers at the moment when they attracted him with "Eyes of Gold". Scrooge, enchanted by their eyes and song, jumps off the yacht and swims to the Sirens as Homer and Scrooge's nephews chase after him. Just when Scrooge approached them, the Sirens reveal a large monster hiding underneath them and attempted to eat Scrooge whole, until Homer catches Scrooge with a net and pulls him to safety with the Sirens chasing after them. Once on their yacht, the monster grabs Scrooge with its long tongue and tries to pull him back. Luckily, Dewey throws the anchor and nails its tongue right against a placed rock, hurting the monster and letting go of Scrooge from his tongue's grip. Angered that their prey has escaped and Dewey has harmed their monster, the Sirens sink down with their monster to recover.

The Sirens appear again later near the end of the episode, at night when they hear and saw the tornado carrying Scrooge and his nephews whirl by their island. The sirens' monster surfaces up to see the noise, but did not notice the tornado. So then, the monsters and the sirens sink back underneath to sleep.