MEXICO CITY (AP) – Small Mexican fish make a kind of La Ola wave to avoid eating birds – researchers from Berlin have found that this works. According to a team from Humboldt University, Technical University of Berlin and the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB), the behavior of a two-year-old mole of sulfur could be a signal to raptors: “We know you’re there. You didn’t waste your time attacking us!”
Scientists have examined the behavior of threatened fish species in volcanic springs in the southeastern state of Tabasco, Mexico and have now published the results in the journal Current Biology. They note how fish in schools often numbering over 100,000 dived several times in a row from the surface of the water when the raptors approached or attacked them. Instead of staying deep in the water, they kept returning to the surface. They create waves with their tail similar to the “la ola” (“wave” in Spanish) that spectators make on soccer fields.
Experiments have shown that birds like green hunters wait the longer before the next attack, and the more waves they experience on the first try. Their hunting success also declined. “Because the waves observed were clear, frequent, and regular, and the intervals between individual waves were always the same length, no matter how many times the fish repeated their wave motion, we assume that the wave motions are more than a pure escape reaction,” explained one Study authors, David Bierbach.
So the researchers suspect that the purpose of the waves is to confuse attacking birds. It may also be a signal from the fish to the birds that the attack is not worth it. Birds can also benefit from this by saving time and energy. “Such a win-win situation is necessary so that a collective signal can evolve between prey and predator species,” said Jens Krause, another author of the study.
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