What Draws Amazon Dolphins to Their Own Urine Jets?

In the green immensity of the Amazon, where silt waters wind under the canopy, lives a dolphin with fantastic creature. The Amazon dolphin, recognizable by its pinkish shade and its flexible silhouette, evolves in a world where visibility is reduced and where each interaction is based on subtle signals. However, beyond its vocalizations and its aquatic games, a recent discovery intrigues scientists: these freshwater cetaceans have developed an unprecedented mode of communication, involving a jet of urine projected out of the water. A behavior never observed in dolphins, which could question our understanding of sensory exchanges in the animal world.

Amazon dolphins, creatures apart

Amazon's dolphins, also called boots (Inia Geoffrensis), are among the rare freshwater cetaceans. Living exclusively in the river basins of South America, these dolphins are distinguished by their more flexible silhouette and their pink color which evolves with age. Unlike marine dolphins, their lifestyle in troubled waters has led them to develop singular behavior to adapt to their environment.

Endowed with a sense of ultra-performance echolocation, these dolphins easily navigate in the waters often loaded with sediments of the Amazon. They are also known for their great sociability, their interactive games and a complex communication which includes sounds, bodily postures and tactile interactions. However, a recent discovery has highlighted an aspect that is still unknown to their behavior: males would be able to project their urine into the air, a phenomenon never documented previously according to Popsci.

This observation intrigues all the more since the Dauphin of Amazon evolves in a habitat where chemical communication is supposedly more difficult. The river current quickly takes away olfactory signals, and these cetaceans do not have a smell as developed as terrestrial mammals. So why do they engage in such behavior?

When urine becomes a message

In the animal kingdom, urine is often much more than just organic waste. Many species use it to communicate vital information to their congeners. Foulins, bears and canids mark their territory by urine, depositing chemical signals which indicate their presence or their social status. Certain species of fish and aquatic invertebrates also emit urinary signals to display their dominance or attract a reproductive partner.

This phenomenon is however extremely rare in cetaceans. In water, chemical signals quickly disperse, making olfactory communication much less effective than on earth. This is why dolphins are mainly based on sounds and physical contacts to interact.

The observation of the botos changes the situation, however. By analyzing their behavior, the researchers noticed that the projection of urine is not random. The dolphin deliberately turns on the back, exposes its penis out of the water and emits a jet which rises to more than a meter above the surface. Another dolphin is often present nearby, seeming to carefully observe the liquid trajectory before approaching it. Some individuals even use their rostrum to follow the fall of the urine to the water, as if they were trying to capture precise information.

This unprecedented behavior in cetaceans suggests a more complex function than a simple elimination of body waste. It could be a means of communication specific to the dolphins of Amazon, perhaps in relation to the social hierarchy or reproduction.

A scientific mystery to solve

If this discovery intrigues, it also poses many questions about the ability of dolphins to perceive and interpret these urinary signals. Unlike terrestrial animals, dolphins have a very limited sense of smell, which makes it difficult for the idea that they can capture conventional olfactory information. However, some studies suggest that marine dolphins are able to recognize their fellows thanks to chemical signals present in water.

Research by Stephen F. Austin State University in Texas has shown that the great dolphins (Tursiops Truncatus) can identify their group companions by taste their urine. Using their tongue and receptors located in the mouth, they would be able to extract biochemical information related to the identity or state of health of the transmitter.

This capacity could also exist in Amazon dolphins. The research team at the origin of the discovery has hypothesized that the botos use their sensory mustaches located on their rostrum to capture chemical clues in the urine. Indeed, unlike the marine dolphins that lose their vibrates while growing up, the botos keep these tactile structures, which could allow them to “read” the chemical signals in their environment.

However, researchers remain cautious. Urine communication in Amazon dolphins has not yet been completely elucidated, and several explanations remain possible. Some specialists suggest that this practice could also have a fun dimension, or even serve to attract the attention of another individual without necessarily transmitting precise biochemical information.

Why this discovery changes our understanding of dolphins

Dolphins are already famous for their intelligence and advanced communication capacities. They use a wide range of vocalizations, tactile contacts, and even social games to interact with each other. This new study adds an unexplored dimension to their behavioral repertoire.

If the Botos have really developed a unique way to share information via their air urine jets, this would mean that their communication is much more sophisticated than what we imagined so far. This discovery also opens up fascinating perspectives on the evolution of cetaceans and their adaptation to freshwater environments.