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Eco-Justice Notes
The E-mail Commentary from Eco-Justice Ministries

Fish Are Using Tools
distributed 5/27/16 - ©2016

Delight, wonder, and a small touch of humility.

Those were some of my emotional reactions to an article in the latest Scientific American about remarkable behavior in some fish. In three different kinds of fish, the author describes complex functions that might be called tool use.

These aquatic vignettes are fascinating and fun. They also lead me to ponder some larger questions about humanity's uniqueness within God's creation.

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The Scientific American article, "Einstein of the Sea", doesn't have any breaking news. Each of the three examples has been documented in other reports. Putting them together, though, gives a multiplier effect. One kind of fish using tools is a surprise. Three of them is enough to start stretching some of our conventional thinking.

1) The lead section of the article describes an orange-dotted tuskfish that was filmed cracking open a mollusk shell against a rock -- and repeating the trick three times in 20 minutes.

The fish goes through several steps to accomplish its goal. First, it uncovers a mollusk that is buried in sand by blowing water at it. Then it picks up the shellfish and carries it a substantial distance to a large rock. Finally, "using several rapid head flicks and well-timed releases", the fish breaks open the shell, and eats the animal inside.

Author Jonathan Balcombe -- who is director of animal sentience for the Humane Society Institute for Science and Policy -- puts the behavior into a conceptual framework. "By using a series of flexible behaviors separated in time and space, the tuskfish is a planner."

A video of a tuskfish doing the mollusk-rock thing clearly shows that this isn't an accidental result. This isn't a fish haphazardly tossing around clams and having some of them break open. Another researcher, who observed similar actions, wrote, "It is apparent that this particular individual does this on a regular basis judging by the broken shells scattered around the anvil."

The tuskfish isn't alone in this kind of tool use. Other related species (called wrasses) have also been observed doing similar things that are "remarkably consistent" and "nearly always successful."

2) The second example in Scientific American wasn't a surprise to me -- at first. This talks about archerfish, which use squirts of water to knock prey off of a branch and into the water. I've seen archerfish at the Denver Zoo, and I've read about their surprising accuracy.

This article did surprise me with some additional details. The fish shift their hunting strategies depending on how far away the food is. If a bug is on a low-hanging branch, the fish will just jump up and grab it. If they do shoot water to zap their prey, the dynamics of how the water is squirted out of the mouth will change depending on the distance involved, so that a glob of water forms just at the point of hitting the target. And they can adjust for moving targets, aiming so that the water shot goes where the bug will be at the right time. Impressive.

But there is more! The archerfish is shooting through the air-and-water boundary. They eyes of the fish are under water, and looking into the air causes varying degrees of refraction. (The classic illustration: a pencil standing in a glass of water looks to us like it bends at the water line.) The fish can adjust their targeting for refraction, up to about a 40 degree angle, and still be amazingly accurate. That's a learned ability, not something about the structure of their eyes. (A physics teacher uses the archerfish to teach about refraction. )

But the big surprise, for me, is about how archerfish learn to be such good shooters. It isn't an instinctive behavior, and some of it is learned through practice. The article also tells us that young fish that watched other fish make repeated attempts to shoot down prey were able to make successful shots at rapidly moving targets. "The scientists concluded that archerfish can assume the viewpoint of another archerfish to learn a difficult skill at a distance. Biologists call this 'perspective taking.' ... a form of grasping something from the perspective of another." If I watched a human archer learning how to shoot an arrow at a target, could I hit the bulls eye on my first couple of shots? I doubt it.

3) The third example -- briefly -- deals with cod being studied in captivity. Each cod had an identifying tag attached to its dorsal fin. Some of the fish learned that they could hook the tag onto a feeding mechanism to release a morsel of food. Through practice, the cod developed a "finely tuned series of goal-directed, coordinated movements" using the artificial tag to get more food.

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Scientific American author Balcombe writes, "These are impressive cognitive feats for any animal. That they are performed by a fish clearly upsets the still commonly held assumption that fishes are at the dim end of the animal intelligence spectrum."

A short article in Wired about the tool-using tuskfish raises philosophical questions.

Tool use was once thought to be exclusive to humans, and was considered a mark of our superior intelligent and bulging brains. In recent decades, though, more and more animals have shown an ability to work with tools and objects. ... What specifically constitutes tool use is a controversial topic. Is a seagull using a tool when it drops a shellfish on a rock? How about when archerfish spray a jet of water to knock prey off of twigs? There's also the tricky problem of the ocean having all that watery stuff, and fish having no limbs.

The small touch of humility that I felt when reading about the fish comes from the realization that we humans are not quite as exceptional as we'd thought. Small-brained fish can make plans about how to use other objects to accomplish their goals. They can make targeting decisions about distance, speed and angles that put a star quarterback to shame -- and do it while adjusting for refraction between water and air. And some fish can employ "perspective taking" to learn from the experiences of others.

No, fish have not invented laptop computers, or even the wheel. We humans are very smart and creative. But I have to recognize that our cognitive difference from some other animals is a matter of degree. Research is showing that many species have strong elements of abilities that we've long prized as uniquely human.

As humans reach into outer space, we wonder about finding life, and especially intelligent life. On Mars, or the giant watery moon of Jupiter, or in other solar systems, are there beings that think and plan and have self-awareness? Beyond Earth, are there tool-makers and civilization-builders?

It is humbling to realize that we've missed clues about creatures that think and plan and use tools on our own planet. Tool-using fish can open our minds to larger definitions of intelligent life. The astonishing complexity of life can remind us that we're not alone -- on Earth, or in the universe.

Thanks be to God for the wonders of life, and for our growing awareness.

NOTE: Several years ago, I shared my delight at another remarkably intelligent life form, in "Thanks for the Octopus".


Peter Sawtell
Executive Director
Eco-Justice Ministries

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