Dolphin is called iruka in Japanese イルカ and in kanji 海豚 (umi sea + buta pig). A sea pig? :-)
Shiira しいら is called dolphinfish, yet it is completely different - dorado or mahi-mahi (the latter name from Hawaiian).
And mairuka まいるか is the ocean dolphin, it can grow up to 9 m and 10 tons.
Some photos taken during the show: