Electric fish exploit signals from their peers to hunt
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Weakly electric fish Gnathonemus petersii. Photo: Sawtell Lab/Columbia University Zuckerman Institute
African electric fish can use each other's electric signals to collectively sense predators and prey as they move through dark, murky waters, researchers report.
Why it matters: This sensing and other highly specialized behavior can reveal different information about the brain than studies done in rats, mice and other laboratory model animals.
How it works: Scientists knew African electric fish, Gnathonemus petersii, had receptors on their skin that are sensitive to electricity.
- The fish emit electric pulses that hit objects and return a signal that the fish senses. Objects that are alive cause more current to flow than rocks and other objects — a difference the fish can detect.
- Some scientists thought when the fish got together to hunt in groups, their electric signals would interfere with one another and essentially jam their sensing ability.
- But neuroscientist Nathaniel Sawtell and post-doctoral researcher Federico Pedraja of the Zuckerman Institute at Columbia University found the fish actually benefit from the pulses of other fish.
What they found: Pedraja and Sawtell used computer modeling to simulate the electrical environment of the fish and found having other group members' signals boosted the sensing range of a fish from one body length to as much as three times its length, they report in Nature.
- That finding was confirmed with brain recordings from fish as they responded to their own signals and other fish.
- The researchers also observed the fish in a tank positioning themselves in configurations the simulations suggested would support sensing. They also alternated emitting electric signals.
- Sawtell says the fish sensing system is similar to radar or sonar that uses multiple emitters and receivers to improve sensing.
What they're saying: Finding that these fish "evolved a remarkable way in which they can their use own predictable input and unpredictable input [from other fish] to detect prey when they are hunting together" is "completely new," says Leonard Maler, a neuroscientist at the University of Ottawa who wasn't involved in the study.
The intrigue: African electric fish have one of the biggest brain-to-body mass ratios of any animal — including humans, Sawtell says.
- "We're just beginning to understand how this giant brain of this fish actually makes sense of these different streams of information coming in from different animals," he says.
