This is a brief but cautionary animation depicting sirens. As you can see, sirens closely resemble mermaids. The two creatures are often confused with one another. Both are half-human, half-fish. Both dwell in the ocean. Both species enjoy sitting on rocky shores and singing. Both lure sailors to their fates with their voices.
However, most mermaids are essentially amoral. They are innocent of either good or evil intentions. If they draw unwary sailors to them and these sailors drown while trying to follow a mermaid into the deep, the mermaids will be sad.
A mermaid wants to play with the sailor, not drown him. It is his own action of diving after her that robs him of life…and the mermaid will always mourn for him, singing about their encounter with her beautiful voice as she warms herself on a rocky shore
The siren, on the other hand, fully intends to cause harm to the sailor. She will lure the sailor to her in order to drown him. Sirens delight in tricking ships to wreck on underwater rocks, and in devouring the crew. Mermaids sometimes join these feasts however, after the ship has been destroyed.
Both mermaids and sirens feed mostly on fish… but mermaids, like sirens, do eat men on occasion.