What A Fish Knows

The more we learn about nature the more we come to realise just how little we understand about our world. Science has revealed some fascinating things about animal behaviour—from the intelligence of dogs to the ingenuity of birds, but what about…what a fish knows?

Do fishes think?

Do they really have three-second memories?

And can they recognize the humans who peer back at them from above the surface?

In What A Fish Knows, the myth-busting ethologist Jonathan Balcombe addresses these questions and more, taking us under the sea, through streams and estuaries, and to the other side of the aquarium glass to reveal the surprising capabilities of fishes. Although there are more than thirty thousand species of fish―more than all mammals, birds, reptiles, and amphibians combined―we rarely consider how individual fishes think, feel, and behave. Balcombe upends our assumptions about fishes, portraying them not as unfeeling, dead-eyed feeding machines but as sentient, aware, social, and even Machiavellian―in other words, much like us.

What a Fish Knows draws on the latest science to present a fresh look at these remarkable creatures in all their breathtaking diversity and beauty. Fishes conduct elaborate courtship rituals and develop lifelong bonds with shoalmates. They also plan, hunt cooperatively, use tools, curry favor, deceive one another, and punish wrongdoers. We may imagine that fishes lead simple, fleeting lives―a mode of existence that boils down to a place on the food chain, rote spawning, and lots of aimless swimming. But, as Balcombe demonstrates, the truth is far richer and more complex, worthy of the grandest social novel.

Highlighting breakthrough discoveries from fish enthusiasts and scientists around the world and pondering his own encounters with fishes, Balcombe examines the fascinating means by which fishes gain knowledge of the places they inhabit, from shallow tide pools to the deepest reaches of the ocean.

Teeming with insights and exciting discoveries, What a Fish Knows offers a thoughtful appraisal of our relationships with fishes and inspires us to take a more enlightened view of the planet’s increasingly imperiled marine life. What a Fish Knows will forever change how we see our aquatic cousins―the pet goldfish included.

Jonathan Balcombe on What A Fish Knows (Interview by Inga Yandell)

In this discussion with the author we dive deeper into the research and reveal both the inspiration and some of the curious insights from this pioneering publication.

How did fish become the subject of your new book?

As a scientist working on animal sentience, I was often encountering new studies of fishes showing that they have rich, interesting lives. But most of this information was buried away in scholarly journals that most folks never read. Translating science into something lay-readers find engaging is something I find challenging and enjoyable. And with fishes being the most exploited group of vertebrates on Earth, there was also a strong ethical motive to write a book of popular science about fishes.

Why are the insights of the ocean so vital to our future?

Few of us realize it, but we are totally dependent on healthy oceans for our own survival. The blue-green algae that inhabit ocean habitats produce most of the world’s oxygen. Marine life, including of course the fishes, are a critical part of aquatic ecosystems. As they go, so go their ecosystems (and vice versa), and ultimately, so go us. In 2015, the World Wildlife Fund reported that today there is only about half as much marine life in the oceans as there was in 1970. So we have lost half of all fishes and other sea creatures in less than fifty years. It is a sobering reminder that we need to cultivate a more respectful relationship to the oceans.

How are fish innovating science and what are the primary areas benefiting from this?

It appears that fishes have become the most commonly used vertebrate animals in scientific experiments. However, I do not focus on this in my book “What a Fish Knows,” and I am not enthusiastic about the use of sentient animals in research that causes animals to suffer and die, as much of this research does. Instead, I focus mostly on research into how fishes live their lives—such as how they think and feel, how they interact and communicate with each other, how they find mates and raise their young, how they play, deceive, and cooperate.

How curious and creative is the scope of the studies you researched?

Scientists have been remarkably creative and innovative in coming up with ways to explore the inner worlds of fishes. Some have accumulated hundreds of hours of SCUBA time watching fishes interact and painstakingly measuring their behaviors. Others have created artificial habitats to better understand how fishes respond to different environments. Because fishes can be trained to indicate their preference for one of a pair or group of stimuli, we can determine, for instance, that fishes can recognize each other as individuals, they can recognize human faces, and that they “fall” for optical illusions as we do.

Who are the pioneers, what are the species and where are the locations?

In the 1930’s, the Nobel Prize-winning Austrian ethologist Karl von Frisch made two important discoveries about fishes. He demonstrated fish hearing by training a blind catfish to come for food at the sound of a whistle. He also described an alarm chemical, which he termed “schreckstoff” (translation: scary stuff), that many fish species produce when they become scared. Schreckstoff serves a useful social function by warning nearby fishes that danger, such as a predator, may be lurking.

In a series of captive studies conducted between the 1940s and the 1970s, American scientist Lester Aronson showed that a little fish of the intertidal zone called the frillfin goby, was able to leap accurately to neighboring tide-pools thanks to the uncanny ability to memorize the topography of their habitat by swimming over it at high tide. Not only that, but the gobies were able to memorize the tide-pool layout in just one go and they could remember it 40 days later.

Is the science applicable to people now, or are the revelations subject to further investigation and development?

It is one of the paradoxes of knowledge that the more we know, the more there is to discover. For example, until it was discovered that frillfin gobies could jump to a neighboring tide-pool without ending up stranded on the rocks, nobody was asking how they did this. And now that we know how, we may ask questions like what part of the brain performs this feat, do they enjoy learning it, and can these gobies perform other memory feats unrelated to tide-pools, etc.

What are three things a fish knows that will surprise and inspire readers?

There are so many, but here are three.

Grouper fishes perform a head-shaking gesture to invite moray eels to hunt with them as a team, and both fishes are more successful when they hunt cooperatively than when they hunt alone.

Sharks will swim up to trusted divers who stroke their heads and bellies, sending the sharks into a state of extreme relaxation, in which they will allow the divers to remove fishing hooks imbedded in their mouths.

A tiny male pufferfish from Japan spends hours carefully constructing an exquisite, six-foot-wide circular nest in the sand, with concentric rings of fingerprint-like ridges, into which he hopes to attract a female. He decorates his artwork with pieces of crushed shells, which help cover and protect the female’s fertilized eggs.

Events and other info: www.jonathan-balcombe.com

What A Fish Knows is available on Amazon.

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Inga Yandell
Explorer and photo-journalist, passionate about nature, culture and travel. Combining science and conservation with investigative journalism to provide educational resources and a platform for science exploration.
Inga Yandell

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