Fun fact: Dolphins are one of the very few mammals that look in a mirror and recognize that they are looking at themselves and not just "another" animal.
Like any living thing they just try to pleasure themselves - sleep, food, sex, choose any of them. The thing is, the more intelligent you get, the more ways you find to get those things. Typical animals only know of normal sex, those with better functioning brains learn of rape, and rape of other species / inanimate objects & so on.
I DO APPRECIATE THE EXPLOITATION OF BEAUTIFUL ANIMALS LIKE THAT. You can see healed wounds from blunt objects with the naked Eye. SHUT DOWN SEA WORLD. shut your legs!