River Dolphins Get Weird With Anaconda Who Don't Want None, But Gets Some Anyway


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

dolphin anaconda interaction

Close inspection of the play date revealed a curious degree of arousal among the dolphins. Image credit: Entiauspe-Neto et al 2022, Ecology. CC BY 4.0

Charismatic dolphins are considered fun, playful creatures, and they can be, but they’re also highly sexual beings. The convoluted anatomical puzzle that is dolphin mating is believed to strengthen social bonds and be a pleasurable experience, with females having feel-good nerves in their clitorises.

Object carrying has been observed among Amazon river dolphins (Inia geoffrensis) as a sexual display, wielding anything from plants to stones and clay. However, more recently, and perhaps most bizarrely, a bunch of Bolivian river dolphins were observed getting weird with a predatory anaconda.


A group of Bolivian river dolphins (Inia boliviensis) were spotted by researchers conducting fieldwork in the Beni floodplains of Bolivian Amazonia. They appeared to be in a heightened state of activity, spending longer with their heads above the water than normal, which enabled the researchers to spot a Beni anaconda (Eunectes beniensis) in some of the dolphins’ mouths.

The “game” of Pass The Anaconda was thought to be an example of object play in which animals interact with an item, living or dead. This is popular among oceanic dolphins too who will pass anything from sea sponges to potent puffer fish (anything to get high) during play.

The dolphins’ exact motivations are difficult to deduce but in a write-up about the observation published in Ecology the authors state they don’t think there was any interest in eating the involuntary play mate. However, after reviewing photos taken during the play, the researchers made another curious observation.

“Afterwards, we were able to observe on the photographs that the adult males were sexually aroused while engaging in object play with the anaconda,” they wrote.

river dolphin anaconda
"I don’t think that the snake had a very good time." Image credit: Entiauspe-Neto et al 2022, Ecology. CC BY 4.0

Male-male sexual interactions are far from unheard of among dolphins, so it's possible the adults were already engaged in something that the anaconda happened to unwittingly slither in to. The object "play" may have been a way for the animals to satisfy some of their urges by rubbing up against its body.

Possible dolphin pleasure aside, once caught up in the action it seems unlikely the anaconda’s experience was a good one.

“I don’t think that the snake had a very good time,” said biologist and co-author Dr. Steffen Reichle of the Noel Kempff Mercado Museum of Natural History, Bolivia, to The New York Times.

It’s estimated the snake was handed around for a minimum of seven minutes during which time the researchers observed it to be immobile and largely kept underwater. Considering it didn’t appear to be a long-dead snake with no obvious signs of bloating or floating, they suspect it could well have died during the interaction.


A puzzling observation, no doubt, but also a seminal one as the researchers state it marks the first recorded interaction between a Bolivian river dolphin and a Beni anaconda, even if the snake would give it: 0/10, would not “play” again.

[H/T: The New York Times]


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