dolphinsu wa chiteki to shakai no kaiyū mammal da. Cetacea no jūdan to Delphinidae no kazoku ni hairu. kireji to shinkū na karada, hazama, shigoto no katsuyō, mizu no naka de kōka to kōka o kakeru koto ni shite, supekutāku na suijō kyōgi o shōshō suru.