Ground Report | New Delhi: Some fish can swim even after death; “What is dead cannot die.” This phrase from the Game of Thrones series seems to make no sense since once a being dies, it stops performing all its functions and even exists. However, once again, the reality is more than fiction and, indeed, we can find many extraordinary related situations, such as a fish being able to continue swimming against the current despite lacking life.
Some fish can swim even after death
Specifically, that scenario was what a team of researchers from MIT and Harvard encountered while studying how to live trout conserve energy by swimming behind obstacles that block water currents. During one of the experiments, the scientists poured a dead fish into the test channel instead of a live one, but, to their surprise, the inert being began to behave in the water as if it were alive.
“It was incredible and very counterintuitive at the same time. I had no idea that trout were able to swim upstream without expending energy, “said Michael Triantafyllou, a researcher at MIT, in this study published in the Journal of Fluid Mechanics.
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From that moment, researchers began to investigate the matter and discovered that the key to this mysterious phenomenon lay in objects that block the natural flow of water, such as rocks.
Diversity situations that fish face
According to their observations, the vortices that are created in the current as the water flow hits the obstacles are capable of shaking the fish’s head and their tails in resonance. This tilts the body in such a way that the vortices, which cause a pressure drop, apply a suction force that propels the fish forward.
“You have a flow behind the obstacle that creates a continuous stream of eddies. Each eddy contains energy and also causes the pressure in the fluid to decrease. The eddy causes the body to shake from side to side, and the fish manages to extract energy, ”explained Michael Triantafyllou.
It should be noted that the vortices are sometimes not capable of generating this movement in the fish by themselves. During the experiment, the researchers observed that in order for the fish to extract enough energy from the current to overcome its own drag, it must be positioned very carefully. If it is very close to the vortices, the suction of the obstacle would attract it. If it is too far away, they will not be able to take advantage of this benefit.
Faced with the great diversity of situations that fish face, they are equipped with sensors that help them to position themselves in the best position, thus bringing their biological qualities into play: “If you want to do it in real life, you cannot trust in accidents, ”said Triantafyllou.
This finding was discovered more than a decade ago, but the team of researchers has not stopped experimenting and continuing to work based on the phenomenon of vortices and the great sensory capacity of these aquatic beings.