Mermaids are women with the tail of a fish instead of legs. It is said that each mermaid has a girdle, and if a man can find it and hide it, then the mermaid who owns it must grant the man any wish he desires. If she manages to find her girdle and take it back then the wish she has granted will disappear.
Mermaids have no souls when they are born, but can get one if they marry a mortal man. Mermaids make excellent wives, but they must always content with the call of the sea; if it becomes too loud the mermaid will return to her watery home and leave her life on land behind.
Mermen are the male equivalent of Mermaids.