Surviving in an unpredictable ecosystem requires more than just adaptation. In environments where fresh water mixes with salt, some species develop unexpected strategies to maintain their internal balance. Among them, the soft shell turtle illustrates a form of biological ingenuity which intrigues researchers and upsets the received ideas on the functioning of the living.
Singapore biologists have observed surprising behavior in this turtle. Indeed, she often plunges her head into puddles, without ever drinking. However, his language is agitated with each immersion, as in a gesture learned. At first glance, the action seems harmless. However, it reveals a remarkable strategy. According to a study published in 2012 in the Journal of Experimental Biology, this reptile does not act at random. He actively rejects urea, metabolic waste, directly through the mouth.
Such a strategy is not anecdotal. Rejecting urea usually requires a lot of water, a dangerous luxury in a salt environment. In this reptile, oral excretion then saves body water and avoid the salt trap. If the turtle was drinking to eliminate its waste by renal route, it would worsen its level of blood salt. Ultimately, this mechanism would expose it to a deadly circle: drink more to compensate, while gradually entering.
The soft shell turtle diverts the rules of the living
The effectiveness of this system is based on a complete reorganization of animal physiology. Inside the oral cavity, the researchers discovered folds with structures close to the branchies. Long considered as simple respiratory aid, these training courses are capable of transferring urea from blood to the outside, without going through the kidneys.
To validate this hypothesis, scientists have made a surprising experience. After letting several turtles immerse themselves for six days, they found that only 6% of the produced urea found themselves in the classic urine. On the other hand, when they were removed from the water and exposed to a puddle, the turtles expelled through the mouth up to fifty times more urea than when they were in immersion.
This active rejection depends on a gene expressed only in the mouth of the animal. This gene manufactures a protein that transports urea. This process, completely different from that of the kidneys, intrigues researchers. Moreover, Yuen K. IP, principal author of the study, insists on the importance of this adaptation. According to him, it would have allowed the species to survive despite the hostile conditions.
However, this expulsion through the mouth would not be an isolated case. Other soft shell turtles living in similar environments could use it. Once again, the evolution seems to have bet on finesse rather than strength.
When medicine is inspired by nature solutions
Beyond zoological strangeness, this mechanism challenges biomedicine researchers. According to National Geographic, the example of the turtle opens a fascinating theoretical path. Could we imagine a system for the elimination of nitrogen waste independent of the kidneys in humans?
Today, patients with kidney failure should use dialysis to filter the urea of their blood. This heavy and binding process mobilizes external machines to compensate for the kidney function. However, according to Yuen K. IP, if one managed to activate a oral excretory path in humans, even in a partial way, this would offer a less invasive alternative. The simple fact of rinsing your mouth with water could then be enough to eliminate part of the nitrogenous waste, as does the turtle.
Of course, this perspective remains highly speculative. But it is part of an increasing current of research, that of medical biomimicry. By observing species which, under the pressure of the environment, have reinvented vital functions, human science widens its horizons. In this context, the soft shell turtle no longer represents only a biological curiosity. It becomes a source of inspiration to rethink the functioning of the human body.
