Songs about a mythical alpaca-like creature have taken hold online in China.

The popularity of the grass-mud horse has raised questions about China’s ability to stanch the flow of information.

BEIJING — Since its first unheralded appearance in January on a Chinese Web page, the grass-mud horse has become nothing less than a phenomenon.

A YouTube children’s song about the beast has drawn nearly 1.4 million viewers. A grass-mud horse cartoon has logged a quarter million more views. A nature documentary on its habits attracted 180,000 more. Stores are selling grass-mud horse dolls. Chinese intellectuals are writing treatises on the grass-mud horse’s social importance. The story of the grass-mud horse’s struggle against the evil river crab has spread far and wide across the Chinese online community.

Not bad for a mythical creature whose name, in Chinese, sounds very much like an especially vile obscenity. Which is precisely the point.