During the intimate encounter photographed in Hawaii, one of the whales was seen to be holding the other in place with its pectoral fins while penetrating it. The whale underneath appeared to be ailing, being noticeably emaciated and covered in whale lice, white-colored parasites sometimes found on cetaceans.
The penises of male humpback whales are usually concealed in what is known as a “genital slit” to make it more streamlined while swimming. An unsheathed penis has only been witnessed a small number of times in the past, once while a whale was urinating.
According to the new research paper, cetaceans such as humpback whales could use the genital slit or anus for same-sex copulation, to practice reproductive behaviors or to form a social alliance or assert a sort of dominance.