The three manatee species (Amazonian manatee, West African manatee, West Indian manatee) and the dugong are the four species that make up the Order Sirenia, which was named for the ancient Greek mythological sea creatures called Sirens, who lured sailors to their death with their beautiful music. In the myth, the Sirens are often depicted as enchanting women who hypnotize sailors into falling overboard and dying. The myth about mermaids is believed to have derived from the myth about Sirens as both are very similar in ancient stories, with the only real difference being the famous fish tail that mermaids possess as opposed to Sirens, who traditionally are in human form. Mermaids were traditionally benevolent creatures in mythology, helping sailors, not hurting, like the Sirens, who were beautiful killers, existing solely to destroy men.
It is widely believed by researchers that sightings of manatees, the dugong and the extinct Steller Sea Cow were the origin of the myth about Sirens and mermaids. With their broad flat fluke and gentle nature, these animals would have been easy to approach in a boat without the animal quickly fleeing. Whether the myths were based on these animals or not, scientists named the Order of animal Sirenia after the Sirens due to the long history of Sirens/mermaids myths these animals are believed to have launched.