These Fish Work Together by the Hundreds of Thousands to Make Waves
upstart writes:
These fish work together by the hundreds of thousands to make waves:
"At first we didn't quite understand what the fish were actually doing," said David Bierbach (@CollectiveBRL), co-first author along with Carolina Doran and Juliane Lukas, also at the Leibniz Institute of Freshwater Ecology and Inland Fisheries and Cluster of Excellence Science of Intelligence. "Once we realized that these are waves, we were wondering what their function might be."
[...] They decided to investigate the anti-predator benefits of the animals' wave action. Their studies confirmed that the fish engaged in surface waves that were highly conspicuous, repetitive, and rhythmic. Experimentally induced fish waves also doubled the time birds waited until their next attack to substantially reduce their attack frequency.
For one of their bird predators, capture probability, too, decreased with wave number. Birds also switched perches in response to wave displays more often than in control treatments, suggesting that they'd decided to direct their attacks elsewhere.
Taken together, the findings support an anti-predator function of fish waves. The findings are the first to show that a collective behavior is causally responsible for reducing an animal's predation risk. As such, the researchers say that this discovery has important implications for the study of collective behavior in animals more broadly.
[...] It's clear that the fish's waving reduces birds' chances of carrying out a successful attack on sulphur mollies. What's not yet clear is exactly why that is. Do the birds get confused? Do the waves tell them they've been noticed and are less likely to succeed in capturing their prey as a result?
Journal Reference:
Carolina Doran, David Bierbach, Juliane Lukas,et al. Fish waves as emergent collective antipredator behavior. Current Biology, 2021; DOI: 10.1016/j.cub.2021.11.068
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