Mermaids were in Pirates of the Caribbean:On Stranger Tides,living in Whitecap Bay.Blackbeard needs a tear from one of the mermaids and the Chalices of Cartegena to suceed in his quest for the Fountain of Youth.Syrena,one of the mermaids,is a major role in On Stranger Tides

Pirates 4 mermaid poster

.Mermaids are cunning,alluring,dangerous,beautiful and manipulative.They lure sailors with there beautiful voices and looks and then tear them into the water and devour them with there vapire-like teeth.They are also called Sirens,for there beautiful voices.In the Whitecap Bay battle scene a mermaid named Tamara attack Scrum with her fangs after singin "My Jolly Sailor Bold"