Much like sirens, mermaids would sometimes sing to people and gods and enchant them, distracting them from their work and causing them to walk off the deck or run their ships aground. Other stories have them squeezing the life out of drowning men while attempting to rescue them. They are also said to take humans down to their underwater kingdoms. In Hans Christian Andersen's The Little Mermaid it is said that they forget that humans cannot breathe underwater, while others say they drown men out of spite.
The sirens of Greek mythology are sometimes portrayed in later folklore as mermaid-like; in fact, some languages use the same word for both bird and fish creatures, such as the Maltese word 'sirena'. Other related types of mythical or legendary creature are water fairies (e.g. various water nymphs) and selkies, animals that can transform themselves from seals to humans.