"Mantarays are are listed as Vulnerable by the International Union for Conservation of Nature. Anthropogenic threats include pollution, entanglement in fishing nets, and direct harvesting for their gill rakers for use in Chinese medicine. (Source: Wikipedia)" I like to call them big Birds and they can get really big. They can grow up to 7 m (23 ft) in width!! Mantarays can be very playful. They seem to like certain people. If they do like you and they are in a playing mood , the show seems to be only for you. Mantarays have the biggest brains compared to their size.