SCIENCE LAB SCREAM : DOLPHINS & SERPENTS

Odd Couples

For serpents, dolphins can be playful, and deadly, companions.

In August 2021, researchers were documenting biodiversity near the Tijamuchi River in Bolivia when they saw creatures that are typically hard to observe: Bolivian river dolphins.

Just seeing them with their heads above the river was extraordinary, said Steffen Reichle, a biologist in Bolivia and a member of the team. They knew something was up and started snapping photos.

Only after scrolling through the images taken did the researchers realize the dolphins were dangling an anaconda around as they swam.

The researchers recently described what they saw in the journal Ecology.

While dolphins in captivity and the wild are often playful, the behaviour of the Bolivian cetaceans seems like a new frontier in frolicking among the aquatic mammals, and some scientists still aren't sure what to think about what the team observed.

Dr. Reichle says Bolivian river dolphins usually swim below the surface, but some of the six animals they saw kept their heads above the water for a long time.

At one point, two male dolphins seemingly swam in sync, a snake held by the animals' mouths. Anacondas are semiaquatic and can hold their breaths for some time.

But because the snake was handled for at least seven minutes, much of this submerged, it probably died.

''I don't think that the snake had a very good time,'' Dr Reichle said.

Because of how long this interaction went on, the research team suspects play play - not predation.

Something else from the photos was notable : the male dolphins' erect penises.

''It could have been sexually stimulating for them,'' says Diana Reisa, a marine mammal scientist and cognitive psychologist at Hunter College in New York who was not involved in the study.

The aroused males could have been having a sexual romp with each other before the snake became entangled. [Carolyn Wilke]