A team of researchers from Brazil and Bolivia documented Bolivian river dolphins, Inia geoffrensis boliviensis, alongside an anaconda in the Tijamuchi River region of Bolivia. The scene, captured in August 2021, shows at least six dolphins staying near the surface while the snake sits in their mouths. The observation was part of a portal science alert that linked to a peer‑reviewed study published in Ecology.
River dolphins are less frequently seen than their marine cousins. The cloudy, sediment-filled waters of large river systems make spotting and tracking their movements challenging. Many river dolphins, including the Bolivian variety, face critical threats to their survival. In this particular instance, researchers witnessed a striking display in which two dolphins moved together with a predatory snake positioned between their jaws. Although the precise purpose of this behavior remains uncertain, it aligns with documented patterns among dolphins and other marine mammals, which can be exploratory, playful, or socially driven interactions with other animals.
The August 2021 field note describes a group of dolphins that surfaced longer than typical, prompting closer examination once the photographs were reviewed. The researchers observed that the dolphins were holding a snake in their mouths. They estimated the group to be no smaller than six individuals, though the exact size is difficult to determine in the wild. The team concluded that the dolphins appeared to be playing with the snake rather than attempting to consume it. During a seven‑minute sequence, the dolphins displayed varied interactions, sometimes swimming together, but more often remaining within a limited stretch of the river and moving only about 70–80 meters downstream.
Such dolphin interactions are uncommon and may reflect complex social learning processes. One interpretation is that the adults were teaching younger dolphins how to respond to snakes. Another possibility is that the observed behavior served a sexual function, with adult males showing arousal while engaging with the snake, and with juveniles present as onlookers. These hypotheses are drawn from the photographic record and subsequent analysis, and the researchers stress that further study is needed to understand the intentions behind this activity.
Bolivian river dolphins, or Inia geoffrensis boliviensis, can inhabit river systems in the Amazon basin of northeastern Bolivia. Anaconda Beni, a large snake of the same region, can reach two meters in length and shares habitat with the river dolphins. The unusual event described here likely concluded with the snake spending extended time underwater, which would have led to its drowning in the course of the interaction.