Fishes' Sixth Sense

Fishes' Sixth Sense

The lateral line is a system of sense organs that resides along the head and body of fish, just under their skin. It helps to detect movement, vibrations and changes in pressure in the surrounding water. The canal-like structure is scattered with neuromasts—clusters of sensory cells with hair-like filaments, or cilia, that can detect mechanical changes in the water. 

Water passes through the tube-like structure of the lateral line, stimulating the cilia of the neuromasts and signaling the fish of any changes in its environment. These signals help a fish understand its own movement through the water, in addition to alerting it to nearby predators or prey. A variation in the water could indicate which direction a fish should school, that there is prey nearby or even that it’s time to perform a quick escape maneuver to flee from a predator.


The synchronicity with which some groups of fish swim can be attributed to the lateral line. By allowing them to recognize and respond to the movements of other individuals in the group, the lateral line helps fish school. A massive shoal of sardines can effortlessly navigate together, as seen in the video below. And even without sight, blind cave fish are able to school by virtue of this additional sensory system.

Robotic Fish

A team of European scientists, part of the FILOSE research project, took note of this “sixth sense” that fish possess and are applying it to modern technology. By mimicking the lateral line, they’re working to create an energy-saving underwater robot. The FILOSE team has been testing their robotic fish in a flow tank to see just what this technology can do. 

Like a fish, the robot’s ability to sense changes in water pressure would allow it to evade disruptive currents that would otherwise slow its pace and navigate toward weaker currents, avoiding unnecessary energy outputs.

In addition, the man-made lateral line would enable the robot to detect the speed and direction of a current and adjust its rate accordingly, so it wouldn’t lose ground by drifting downstream. It could even take advantage of strong currents by aligning itself in a way that might help propel it in the right direction.


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