Scientists led by the University of Bristol have been studying a fish’s sensory organ to understand signals of collective behavior that can be used on underwater robots.
This work centered on the lateral line sensor in African cichlids, but is present in almost all fish species, enabling them to sense and interpret water pressures around them with sufficient precision to detect external influences such as neighboring fish, changes in water flow, predators and obstacles.
The lateral line system as a whole is distributed over the head, trunk and tail of the fish. It consists of mechanoreceptors (neurons) that are either within subcutaneous channels or on the surface of the skin.
Lead author Elliott Scott from the University of Bristol’s Department of Engineering Mathematics explained: “We were trying to find out whether the different regions of the lateral line – the lateral line on the head versus the lateral line on the body, or the different types of lateral line sensory units such as those on the skin, versus those Underneath, they play different roles in how fish are able to sense their environment with environmental stress readings.
“We did it in a new way, using hybrid fish, that allowed natural variation to be generated.”
They discovered that the lateral line system around the head has the most significant influence on how well the fish can swim in shallow water, meanwhile, having more lateral line sensory units, neuroblasts, located under the skin causes the fish to swim closer to shallow water. together, while the greater presence of neuroblasts on the skin leads to the fish being further apart.
In the simulation, the researchers were able to show how the mechanisms behind lateral line action are applicable not only at the small scales found in actual fish, but at larger scales as well. This could inspire a new type of easy-to-fabricate pressure sensor for underwater robots, particularly swarm robots, where cost is a big factor.
“These findings provide a better understanding of how the lateral line informs shallow-water behavior in fish,” Elliott said, “while also contributing to a new design of an inexpensive pressure sensor that could be useful for underwater robots that have to navigate in dark or dark environments.”
The team now plans to develop the sensor further and incorporate it into a robotic platform to help the robot navigate underwater and prove its effectiveness.
Research for this paper was funded by the Engineering and Physical Sciences Research Council (EPSRC), the Biotechnology and Biological Sciences Research Council (BBSRC), and the Human Frontier Science Program (HFSP).