Archer fish: how smart are these aquatic “snipers”

His aim could make even Robin Hood look ridiculous. Submerged, this fish can spit out a thin stream of water to knock down its food, even when insects are in mid-flight. These are the archer fish, great gunners of the aquatic world who, despite their amazing technique, did not have exhaustive scientific research on their origins and evolution.

According to a recent study by scientists at the University of Kansas Institute of Biodiversity and the Museum of Natural History, and published in the journal Integrative Organismal Biology, it was possible to get to know a little more in depth not only the evolutionary history of archer fish, whose scientific name is Toxotidae, but also how they learned to spit with aim.

The authors of the research are Matthew Girard, a researcher affiliated with the UK Biodiversity Institute and the Museum of Natural History, as well as a postdoctoral fellow in the Fish Division of the National Museum of Natural History of the Smithsonian Institution; and Leo Smith, associate curator of the Biodiversity Institute and Museum of Natural History of the United Kingdom.

In order to obtain answers about what happens to these fish, the researchers obtained tissue samples, as well as individuals of archer fish from natural history institutions and museums around the world. The objective was to analyze its structures and genetic traits in order to understand the species.

Among the findings, the experts identified that the “oral structures of archer fish support the hypothesis of the blowgun mechanism”. In addition, these small aquatic animals have “oral soft tissue structures that can also play a role in shooting.” The researchers also managed to identify a “sister group” of fish, which would be closely related to archer fish. His name is beach salmon and “by the oral cavity and shooting characteristics” would be relatives.

In the words of Girard, “archer fish are a small group of fish that live predominantly in Southeast Asia and Australia and in many of the intermediate regions” and are “quite intelligent animals: they have the ability to calculate refraction and can hit insects while flying overhead”.

“For the first time we generated a hypothesis of how all these species of archer fish relate to each other. We didn't even really know if they could all shoot. Studies that have looked at how they are shooting or how smart they are are, in general, are using archer fish found in the aquarium trade, but there are also some rare ones,” said the expert. At the same time, he warned that all members of this species “can shoot” or, at least, “have structures in their mouths to be able to shoot, although there are differences between them”.

For his part, Smith said that “there are other fish that eat insects and some that jump out of the water, but I would say that there is nothing like these”. He even recalled that, behind the story of these fish, there is also some myth and a little fantasy. “There is a potentially apocryphal story from the mid-19th century, in India, of archer fish shooting colonizers' cigarettes as if there were a firefly. They were shooting and driving people crazy. This is how Western Europeans discovered what was already there, that everyone already knew,” he said.

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