Despite purported sightings in modern times, mermaids remain mythical, half-human, half-fish-like creatures that appear in the folklore of many cultures across continents, including the first known tale of the Assyrian goddess, Atargatis, and the Pan-African stories of the powerful, water spirit, Mami Wata. Scholars believe that the legends most likely originated from encounters with manatees or other aquatic mammals and spread (and continue to spread) by word-of-mouth, mixing with other ideas.
European ideals may have emerged from the intermixing of Greek legends about sirens and were likely popularized by sailors, African slaves, and later, by writers, such as the various authors and translators of "One Thousand and One Nights" and Scandinavia's Hans Christian Andersen, who is beloved for his 1836 fairy-tale, "The Little Mermaid."
Alternatively called "sea monks", "sea people," "rusalkas" and "sirens," the term "mermaid" derives from the Old English compound of "sea" and "young woman." P.T. Barnum excited interest in the creatures with his 1842 hoax, which unveiled the so-called "Feejee Lady," a fake mermaid that had, in actuality, been rented from a Bostonian museum owner.
Animal Planet did the same in 2012 and 2013, less disingenuously, with its two "docufiction" specials. Though, the creatures were already ubiquitous in pop culture, appearing in everything from art, television and film to ballet and poetry, and the newer phenomenon cosplay.