Amazon river dolphins may send messages with aerial streams of urine

Male Amazon river dolphins have been documented rolling upside down and firing a stream of urine into the air. As if that isn’t bizarre enough, other males will usually seek out the urine as it arcs back down to the water, possibly to receive social cues in a similar way to how land mammals use scent marking.

Claryana Araújo-Wang at CetAsia Research Group in Ontario, Canada, and her colleagues documented the unusual behaviour while…