資料： https://www.sciencealert.com/scientists-discover-a-giant-manta-ray-population-10-times-bigger-than-any-otherhttps://ja.wikipedia.org/wiki/%E3%82%AA%E3%83%8B%E3%82%A4%E3%83%88%E3%83%9E%E3%82%AD%E3%82%A8%E3%82%A4https://ja.wikipedia.org/wiki/%E7%B5%B6%E6%BB%85%E5%8D%B1%E6%83%A7%E7%A8%AE
http://www.nicovideo.jp/watch/sm41443173
