Although researchers have studied humpback whales for decades, they had never documented the sea creatures having sex — until now.
In an unexpected twist, the encounter was between two male whales.
Lyle Krannichfeld and Brandi Romano captured images of the whale copulation while boating recreationally in 2022, according to a news release. The Maui-based photographers reached out to whale researcher Stephanie Stack, who works with the nonprofit Pacific Whale Foundation.
On Tuesday, Stack published a study in the scientific journal Marine Mammal Science about the surprising discovery, which expands our understanding of cetacean social dynamics.
According to the study, this is the first time penetration by a humpback whale has been documented. It is also the first report of sexual activity between two male humpback whales.
"Despite being well-studied for decades, the sexual behavior of humpback whales has remained mostly a mystery until now,” said Stack. “This discovery challenges our preconceived notions about humpback whale behavior. While we have long recognized the complex social structures of these incredible creatures, witnessing the copulation of two male whales for the first time is a unique and remarkable event.”
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The study noted that one whale appeared to be healthy, while the whale being penetrated, appeared to be injured and ailing. The healthy whale approached the other whale from the rear and penetrated it, while holding the ailing whale in place with its pectoral fins.
"Animal behavior is shaped by a complex interaction of internal drivers and external stimuli, making it difficult for researchers to assign motive to an observed behavior," Stack wrote in the study.
The study said some possible explanations for the behavior may be that one whale was mistakenly trying to mate with the other whale, that it was reinforcing a social relationship, or that it was an expression of dominance.
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Most humpback whales spend the summer feeding in polar waters near Alaska and migrate in the winter to tropical waters near Hawaii where they give birth to their young, nurse, and reproduce.
“In many species, the functions of sexual behavior extend beyond reproduction. Heterosexual behavior often occurs in nonreproductive contexts and homosexual behavior is common in the animal kingdom,” Stack wrote in the study.
The study said researchers have documented same-sex sexual interactions in other marine mammals, including walruses, gray seals, dolphins, orcas, gray whales and bowhead whales.
According to the Pacific Whale Foundation, a humpback whale’s penis can be up to 10 feet long and is usually concealed inside the animal’s genital slit. The study said there have been very few reports of penis extrusion by male whales. In male cetaceans, same-sex activity can involve insertion of the penis of one male whale into the genital slit or anus of another male.
The study opens up new avenues for research, as many questions about the sexual behavior of humpback whales remain unanswered. According to the study, additional observations and further research will increase our understanding of similar behavior in humpback whales.
Michelle Broder Van Dyke covers the Hawaiian Islands for Spectrum News Hawaii. Email her at michelle.brodervandyke@charter.com.