Male Humpback Dolphins Woo Mates By Presenting Sponges as Gifts

They also use “wingmen” and occasionally sport the sponges as hats—but researchers aren’t sure just how much game they really have

"Perhaps you'd be interested if I had a sponge?" Wikimedia CC

Humans might be the masters of wooing the opposite sex with tokens of our affection—flowers, food, Knicks tickets, and more. But we're not the only ones. As Sarah Collard reports for the Australian Broadcasting Corporation, at least one species of dolphin collects marine sponges to curry favor with potential mates.

For more than a decade, Simon Allen, marine biologist of the University of Western Australia’s School of Biological Science, cataloged the behavior of humpback dolphins along Australia’s northwest coast. It was during this time that he spotted male humpbacks tear large sea sponges off the ocean floor. They would bring them to the surface and toss and play with them to seemingly impress the females. If they are not impressed by his sponge-catching and tossing skills, the male dolphins sometimes throws it at her. 

“It could be gift-giving in the sense that humans do it — diamond rings [and] roses and the like — in order to impress a female or to suggest that he is somebody that would be a really wise idea to mate with,” Allen tells Collard. The research appears in the journal Scientific Reports.

According to a press release, such behavior is extremely rare in nature, and Allen and his team didn’t recognize the gift-giving in the beginning. “We were at first perplexed to witness these intriguing behavioral displays by male humpback dolphins, but as we undertook successive field trips over the years, the evidence mounted,” he says. “Here we have some of the most socially complex animals on the planet using sponges, not as a foraging tool, but as a gift, a display of his quality, or perhaps even as a threat in the behavioral contexts of socializing and mating.”

Though rare, using objects in wooing behavior is not unheard of in the animal world. Bowerbirds build literal love nests, strewn with pretty pebbles and shells. The spider Paratrechalea ornata offers silk-wrapped insects to its paramour. Even so, the whales behavior is surprsing.

As George Dvorsky reports for Gizmodo, just getting the sponges is mildly impressive since they're stuck to the seafloor and spew a toxic compound to chase away predators. The capacity to obtain such a treasure might be a sign of intelligence and sexual fitness.

Along with the gift giving, the male dolphins also sometimes play a special tune, blowing a trumpet like sound out of their blowhole to attract the ladies. They also make an impressive “banana pose,” which we assume is similar to a human flexing his ripped abs. They even occasionally wear the sponges on their foreheads like hats, because that is universally fly.

There was also another unusual behavior among the male dolphins: as co-author Stephanie King says in the press release, it appears that male dolphins occasionally team up with a “wingman” to woo the female dolphins in pairs.

“The formation of alliances between adult males for the purposes of coercing females is uncommon, since mating success cannot be shared,” says King. “This is a new finding for this species, and presents an exciting avenue for future research.”

While it's nice to think of dolphins wooing one another with sponges and smooth jazz, Dvorsky reports that it might not be as romantic as we’d hope. Instead, the sponge tossing might be a type of intimidation or dominance display, similar to the way chimpanzees—and middle school boys—shake branches and throw rocks at females of the species.

It’s also not clear if the female dolphins actually respond to all the tomfoolery. In the next step of the study, Collard reports that the researchers want to test the dolphin’s genetics to see if the amorous sponge-tossers actually father more offspring or if they are just embarrassing themselves.

Whatever the case, we now know that dolphins sometimes wear hats—and that’s really what’s important.

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