If you’ve ever frightened a fish in its natural habitat before, then you’ve likely observed that all the surrounding fish quickly move away from the frightened fish’s position and avoid it for some time before returning. This behavior has long baffled animal scientists, but new research conducted by researchers from the University of Saskatchewan may indicate why this happens.
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Citing their paper, which was published this week in the Journal of Animal Ecology, scared fish may communicate danger with their brethren by releasing chemicals in the water around them. As you might come to expect, nearby fish sense the presence of these chemicals, thereby warning them of imminent danger much like an alarm.
The notion that fish release chemicals in the water around them isn’t new; in fact, scientists have known about it for decades. The challenging part was discerning why fish released the chemicals in the surrounding water, and that’s precisely what the new study took into consideration.
The researchers were particularly intrigued to learn that scared fish released their chemical signals more often when accompanied by familiar fish. Captivatingly, scared fish were less likely to relay these chemical-centric signals when accompanied by stranger fish or when alone.
"When minnows were present alongside familiar minnows, they were much more likely to produce signals that initiated close grouping of nearby fish, a strategy used to avoid being eaten by predators," explained Bairos Novak, the lead author of the study.
The researchers believe fish developed this communication method as a means of predator evasion, one that wouldn’t be obvious to predators, but would be discernable by friends and family such that it could warn them of impending danger(s).
Nearby fish that sense the chemical concoction are said to respond to it in different ways. Some would immediately disperse, others would freeze in their tracks, and the rest would band together in larger groups. Perhaps unsurprisingly, each of these behaviors is a fright response that fish use to evade predation.
"It is exciting to discover a new signaling pathway in animals," added study co-author Maud Ferrari. "We found that fish are able to manipulate the behavior of other individuals nearby by issuing a signal."
Armed with this new knowledge regarding fish-based chemical communications, it’s expected that scientists will continue researching the behavior in different species to determine if it’s unique to certain types of fish and whether similar chemicals are used from one species to another. It should be interesting to see what they find, but then again, only time will tell…