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The two whales penetrating off the Hawaiian island of Maui

Photo: Lyle Krannichfeld / Brandi Romano

The social life of humpback whales has been studied for decades.

However, little was known about sexual behavior.

There are behaviors


with reproduction, but humpback whale copulation has never been documented.

Now, for the first time, researchers have succeeded in observing and photographing sexual activity between two humpback whales.

The surprise: there are two male animals.

A study published in the journal “Marine Mammal Science” describes the encounter.

It was therefore more of a coincidence when photographer Brandi Romano and her colleague Lyle Krannichfeld were traveling in an eight-meter-long boat off the Hawaiian island of Maui on January 19, 2022.

Suddenly two whales approached, about three to five meters below the surface of the water.

One of the two had an unusually gray body color, which aroused the interest of photographers.

They turned off the boat's engine and watched and photographed the two whales for about half an hour as the animals interacted with each other and slowly circled the boat several times.

One of the two whales was visibly emaciated and covered in whale lice, a type of parasite that lives on the skin of humpback whales and was probably responsible for the gray coloring of the skin.

The skinny whale appeared to swim away from the other whale, but without making any sudden or forceful movements or diving, the study says.

It is unclear whether the weak whale wanted to swim away from the stronger one and perhaps sought refuge behind the boat, or what other dynamic was behind the pursuit of the weaker whale.

Both whales remained within approximately 5 meters of the surface throughout the encounter.

The pursuing whale had an extended penis throughout the entire encounter.

The penises of male humpback whales are usually hidden in a so-called "genital slit," perhaps to allow the whale to be streamlined while swimming.

An uncovered penis has only been observed a few times in the past, once during the urination of a whale.

The second whale repeatedly approached and penetrated the weaker whale, appearing to hold it in place with its pectoral fins.

The penetration attempts were superficial and were visually estimated to be a few centimeters deep.

Each penetration lasted less than two minutes.

After the final penetration, the second whale dived and did not resurface, the first whale remained near the boat for a few minutes before also moving away.

No other animals were involved in the interaction.

Same-sex sexual behavior is widespread in the animal kingdom and has been observed in dolphins and killer whales, but never in humpback whales.

Stephanie Stack, a marine biologist at the Pacific Whale Foundation and lead author of the study, said in the British Guardian that the sexual behavior of humpback whales "has largely remained a mystery."

"This discovery challenges our preconceptions about humpback whale behavior," she said.

"We have long known the complex social structures of these incredible creatures, but witnessing the copulation of two male whales for the first time is a unique and remarkable event."

The exact purpose of the two whales' behavior is unclear

According to the scientific article, the goal of the interaction between the two humpback whales is unclear.

Is it simply about sex, testing reproductive behavior or establishing a form of dominance?

The latter is also the interpretation of photographer Brandi Romano.

One of her pictures of the two whales was awarded at the Ocean Art 2023 photography prize. She sees the whales' behavior primarily as a power play, as she writes on the website: "The other whale seemed to use the injured whale as a 'target' by didn't allow him to come up for air and constantly harassed him." It should be noted that she is not a biologist, but a photographer.

In many species, the functions of sexual behavior extend beyond reproduction.

Heterosexual behavior also often occurs in non-reproductive contexts.

Sexual interactions between individuals of the same sex have been documented for a variety of species: rhesus macaques, sheep, lions, flamingos, vultures or storks.

Humpback whales grow up to 16 meters long and can weigh up to 36 tons, which is the weight of several buses.

They typically spend the summer in polar waters before migrating to warmer, tropical climes in the fall and winter.

Their population has recovered somewhat in recent decades after their existence was once threatened by commercial whaling.