It may be hard to believe the legend that sailors long-at-sea once considered manatees to be mermaids. The manatee nickname – the “Sea Cow” – which comes from the herbivores’ affinity for grazing on vegetation and their slow, ambling way just makes more sense. But a U.S. Geological Survey video reveals that while they may be cow-like, they also have more than a bit of the magical mermaid to them.A USGS video about manatees reveals that while the animals may act like the cows of the sea, they also have more than a bit of the magical siren or mermaid about them.