Mermaids of Pirates of the Caribbean on Stranger Tides

They are the mermaids of the Pirates of the Caribbean On Stranger Tides, While on his way to the fountain of youth, Jack Sparrow will encounter these mermaids and they will play a very big part in th story.
The question is, does these mermaids holds the key of the secret of the fountain of youth?
Watch Pirates of the Caribbean on Stranger Tides Online tomorrow and know what are the story behinds these beauties in the Caribbean sea.