Dolphins are known to be highly intelligent and social creators, they are also known to be one of the few living organisms that have sex for pleasure and not just procreation.
In the 35 seconds long video, a Dolphin is seen placing a dead fish whose head was seemingly bitten off by the same Dolphin. The fish was placed at an angle so that the open flesh of the fish faced the Dolphin in clear view of the zoo attendees.
Next, we see the Dolphin erecting its penis and pushing it into the soft flesh of the dead fish, this procedure was continued until the video ends.
Watch the viral footage below: