A bizarre experiment from Israel suggests goldfish are capable of navigating environments far removed from their natural habitats.
Getting goldfish to drive a vehicle on dry land seems a bit extra, but there’s a method to this apparent madness. Biologists Shachar Givon and Matan Samina from Ben-Gurion University of the Negev in Israel wanted to test the navigational skills of goldfish outside their accustomed habitat, which could shed new light on the origin of navigational skills in general.
More technically, the scientists sought to test the “domain transfer methodology,” in which “one species is embedded in another species’ environment and must cope with an otherwise familiar…task,” in this case navigating through a terrestrial environment as opposed to an aquatic environment, as the scientists write in their new study published in Behavioural Brain Research.
The new research draws on similar experiments done in the past, including vehicles guided by rats and dogs. Importantly, a fish-driven car has already been created, but that was “an observational report, rather than a scientific study, and did not include a methodological examination of navigational capacities,” according to the new paper.
For the experiment, the team designed and built a Fish Operated Vehicle, or FOV for short, because we now apparently need an acronym to describe such things. The goldfish car consists of a water tank, four motorized wheels, a computer, a camera to track movement, and LIDAR to identify the vehicle’s location (the team has provided instructions for those wanting to build their own FOV). When driving at full tilt, the fish moved at a humble 0.93 miles per hour (1.5 km/hr).
“The vehicle was designed to detect the fish’s position in the water tank and react by activating the wheels such that the vehicle moved in the specific direction according to the fish’s position,” according to the study. “In this way, the vehicle’s reaction to the fish’s position allowed the fish to drive the vehicle in the environment.” So, if a fish was swimming near the wall of the water tank while facing outward, the FOV moved in that direction, but if the fish faced inward, the FOV stopped moving.
A total of six goldfish (Carassius auratus) were used in the experiment. Each session lasted for 30 minutes, with a maximum of 20 trials to avoid overfeeding. Working in an “arena” measuring 9.8 feet (3 meters) by 13 feet (4 meters), the fish eventually learned to navigate their FOV to a pink target, which they did to receive a food pellet reward.
The fish got progressively better at the task over time, finding more direct routes and receiving rewards more frequently. The researchers tried to make the task more difficult by altering the starting location in the arena and by changing the location of the pink target. They also added decoy targets colored in green, blue, and orange. The goldfish consistently brushed these added complications aside.
As the researchers conclude, “this study suggests that fish can learn to control a vehicle and use simple navigation strategies to successfully perform a task.” The new findings “suggest that the way space is represented in the fish brain and the strategies it uses may be as successful in a terrestrial environment as they are in an aquatic one,” the scientists claim. “This hints at universality in the way space is represented across environments,” they add, saying that future research “should test this methodology on a terrestrial animal in an aquatic environment to reach more decisive conclusions.”
This experiment is interesting and definitely fun, but it’s not immediately clear to me that the fish were knowingly operating a vehicle or that they even knew they were operating within a terrestrial environment. The fish were just doing fishy things—namely swimming towards a target—which led to the reward. The scientists admit as much, saying the FOV could eventually be used to study motor adaptations in fish, “since the computerized control system can be modified to include a constant distortion in the mapping between fish behavior and vehicle response.” In other words, the FOV could be designed such that the fish would have to do un-fishy things, like swim in a direction away from the target in order to drive the vehicle toward the target. That would truly be impressive and a stronger sign that fish are capable of adapting their navigational skills in unfamiliar contexts.
As already noted, rats and dogs have previously been shown capable of driving vehicles, but a fascinating experiment from 2018 took this concept to another level: plants. Called Elowan, the robot-plant hybrid moved toward a light source in an action triggered by the plant itself.