Ocean STEMulation: Robofish


Focusing on science, technology, engineering, and math, as they pertain to the ocean.

 

Have you ever seen a school of fish travel together and wondered how it works? How do they decide which way to go, and swim closely together, making complex maneuvers without colliding? Decisions are made by consensus or by an individual leader, and the fish are able to respond rapidly to the movement of their peers.
Though the answer isn’t complete yet, various scientific studies have furthered our understanding of this.

Schooling amberjack near Cocos Island, Costa Rica. How do they do this? Photo by Shmulik Blum.

In 2010 scientists designed a robotic fish that blended in with real fish enough that they treated it as one of their own. The “Robofish,” a computer-controlled plaster model of a three-spined stickelback made the cut. The researchers programmed it to swim slightly faster than the others, to act like a leader.


Image of Robofish, a computer-controlled plaster model, courtesy of University of Leeds.

Introducing Robofish: Leading the crowd in studying group dynamics.” ScienceDaily

In a familiar tank, the fish were independent, and likely to explore the tank on their own; the leader’s influence was minimal. When the fish were placed in a new tank however, they were nervous and stuck closely together. They were also more likely to move in a certain way if a bolder member of the group led the way. The researchers found that the fish closest to the leader would be most influenced by the leader’s behavior, but that it didn’t matter exactly how close or far that was.

A new study followed a similar method. Researchers tested how different swimming speeds and different water flow speeds affected how the live fish responded to the robot. The researchers found that fish were more attracted to the robot when it moved like a real fish than when it was still and that the faster its tail beat, the more it was perceived as a leader. They also noticed that the fish who were followers beat their tails more slowly. This could mean that the leader creates a wake that gives a hydrodynamic advantage to the followers, making it easier for them to swim.

 

The researchers have suggested that this type of work could one day be used to guide wild animals, steering them out of harm's way - for example, leading a school of fish away from an oil spill.



Robotic fish are useful in many types of experiments. Click here to read about how one was developed to have the ability to detect water flow, like a real fish.

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