The dolphin might be signaling that it’s getting ready to charge. The S-posture is not unique to dolphins in the Bahamas. It’s been documented in other species during intense aggressive situations, including in male humpback whales in Hawaii and captive beluga whales.
In addition to displaying a threat, Dolphins use the S-posture during courtship or mating. Denise Herzing has observed that a male will approach a female in an S-posture, and orient his rostrum to the female’s genital area while also buzzing that region with his echolocation. This genital buzz is a kind of foreplay from a distance, and its possible could even have a physical effect on the recipient female!
Picture Credit : Google