Based on Scottish Mythology
Sirens are often seen as synonymous with merfolk but this is not the case. Sirens originated from women that were thrown overboard "Because it was unlucky for a woman to be on a ship" and their husky voices are from their ravaged throats as they screamed and choked on salt water. As they descended into the depths of the ocean, their tears mixing, the ocean felt for them and imbibed them with majik giving them the ability to breath in water.
They sing an enchantment song, stronger than any love spell, which is known to bring many a sailor to their death. They feed off ones spiritual essence and can control emotions via music.