The first tool-using (?) fish

July 11, 2011 • 5:03 am

Many species, including crows, chimps, and capuchin monkeys, are known to use tools, but a new paper in Coral Reefs by A. M. Brown et al. (paper free at link and highlighted in Science NOW) reports what may be the first documented case of a tool-using fish.

On November 12, 2006, one of the authors (Gardner), diving off the Great Barrier Reef, observed a black spot tuskfish, Choerodon schoenleinii, holding a cockle in its mouth and repeatedly striking it against a rock until the shell broke.  This was documented photographically below:

According to Science NOW, this is apparently not a one-off behavior:

The tuskfish caught on camera was clearly quite skilled at its task, “landing absolutely pinpoint blows” with the shell, Brown says. A scattering of crushed shells around its anvil rock suggests that Gardner didn’t just stumble upon the fish during its original eureka moment. In fact, numerous such shell middens are visible around the reef. Blackspot tuskfish, members of the wrasse family, are popular food fish, so it’s surprising that its shell-smashing behavior has remained unknown, Brown says. “My feeling is that when we go out and really look for it, it’ll turn out to be common.”

Now whether you see this as “tool using” of course depends on your definition of “tools.”  Italian primatologist Elisabetta Visalberghi says that this is not tool-using because her definition “requires the animal to hold or carry the tool itself,” and this fish didn’t carry the rock.  In fact, that kind of tool use would be impossible for most marine species, however smart (cephalopods are an exception).  But it is tool use according to the definition of Jane Goodall quoted by the authors: “the use of an external object as a functional extension of mouth or hand in the attainment of an immediate goal.

I’m not quite clear why animal behaviorists argue so strongly about what constitutes a tool.  What seems more important to me is whether an animal has the cognitive and learning capacity to use things in its environment to fulfill its “desires.”  Whether or not it carries things to do that seems to be a tangential issue.

Regardless, if this is a learned behavior (and I suspect it is), then it says something new about the intelligence of fish.


Jones, A. M., C. Brown and S. Gardner. 2011 Tool use in the tuskfish, Choerodon schoenleinii.  Coral Reefs: DOI 10.1007/s00338-011-0790-y

47 thoughts on “The first tool-using (?) fish

  1. I think that as a primatologist, Visalberghi may have a bias that leads to an exclusionary definition of a tool. Fish don’t have hands, right? Yes, there are lobes, but c’mon, tool use limited to hands?

    Talk about privileging.

    1. good question.
      More: Learned when and from whom?

      Learning by observation is very difficult (i.e. mostly impossible) to demonstrate, even in laboratory primates. Intentional teaching is even rarer, chimps only afaik.
      It would be a huge deal in any fish.

      1. Also ants:

        There’s been a fair amount of discussion about this among animal behaviorists, since obviously ants don’t have the cognitive abilities of chimps or meerkats. But I think the tandem running as teaching is now pretty well accepted.

        1. Sometimes tool use is amusingly puffed up as something super-duper complex that couldn’t possibly be done without an officially recognised Ph.D. in engineering.

          There was a Chicken-something on Youtube who argued that a chimp wasn’t using a spear because it had only sharpened one end of a stick. It’s just a sharp stick, I tells you! Not a spear!

          And I once got into an argument with an “humans are the only animals who don’t live in harmony” person who did say that chimp massacres don’t count as warfare for the explicit reason that they did not write declarations of war and file the paperwork.

  2. PZ will live this line “cephalopods are an exception”!

    Perhaps it says something about what we call ‘intelligence’? Is intelligence not more about self consideration, self refection, contemplation of existence as a being than just tool use? Perhaps intelligence is as illusory as free will!

  3. Are there any apparent adaptations for the behavior? Like a jaw structure for gripping shells, or harder bones for more effective blows against rocks?

    1. Actually, that issue is mentioned in the Science Now piece. It’s not considered a tool, I guess, because water drops aren’t “objects”, I guess, though it’s certainly on the continuum of “using parts of the environment to get what you want.”

      1. A rose climbing a trellis is arguably “using part of the environment to get what it wants,” but presumably we’re not going to call that tool use.

        On the flip side, if a spider built its web from found bits of string instead of from its own secretions, surely that would count as tool use.

  4. When my cat has a piece of feces stuck on her butt, she rubs her butt on the carpets to dislodge the feces. If we go by these authors’ definition, my cat’s behavior is also an example of tool use.

  5. I can’t hold a millstone with my hands but can still use it as a tool to grind grain.

    I don’t see why using a stationary rock isn’t tool use.

    I also drop bags of ice on the concrete floor to loosen the cubes up. The floor is clearly a tool used to get beer cold.

    1. So, the eagles that open turtles by carrying them up and dropping them are using the ground as tool?

      I suppose I’d consider the fish to be using a tool if they made an effort to select a good rock for opening their shells. Just beating it on whatever rock is handy seems more like environmental use, and is an interesting behavior, but its not quite in the same league as selecting an object from many (and potentially manipulating it) and preferentially using it for a task.

      On a side note, do people consider otters cracking open shells with rocks to be tool use?

      1. I think even more impressive than tool use is tool forming.

        Lots of animals use external things to achieve a goal, but very few actually form a tool that I know of. Crows can, and that is cool.

        1. Corvids are great. 🙂
          And yes, crafting tools, and selecting a tool before it is needed, maybe even carrying it just in case, are more impressive behaviours.

  6. “requires the animal to hold or carry the tool itself,” and this fish didn’t carry the rock. ”

    hmmm by that definition a table saw is not a tool… who’d a thunk

  7. I think its silly. If we use that standard for tool use, then even raptors that pick up their prey and drop it to kill it or break it open (like for clams and mussels etc) are tool users.

  8. I think this thread is going to go a long while. I will decline to try to attempt a definition of tool use. I will simply point out that this is a more sophisticated behavior than the the “head bash” routine that monitor lizards and kingfishers use to kill their prey. Birds and reptiles who do this simply shake their heads in a U-shaped motion until their prey is knocked out by having its head bashed on the ground or perch.

    This fish does something more complex because it has to decide what to ram the cockle into. Ramming it into the silt just won’t do.

    Some of you may not know this, though most of you probably do. You may have seen cockle shells on a necklace. That little hole in the shell was not drilled by a jewelry maker. It was drilled by a whelk that injected its digestive juices through that hole and sucked it out through that hole.

  9. The very limited definition of tool use is often commandeered by certain primatologists, who desperately seek evidence for declaring primates more advanced than lowly reptiles/fish/invertebrates.

  10. In Asia I’ve seen folks using a sharpened wooden stick fixed in the ground to remove coconut husks. I guess the sharpened stick wouldn’t be considered a tool by some people since the folks using it don’t hold it. I guess tapping a husked coconut on a hard surface to crack it isn’t tool use either. I wonder why there is such variation in the definition of tool use.

  11. An engineer I know describes a house as “a tool for living”, by this definition a burrow or a nest is a tool, to say nothing of a beaver’s dam, and one the animal has made itself. I don’t see how a spider’s web could be other than a tool for catching dinner either.

      1. Why should that matter? A rope made from human hair is just as ropy as one made from grass. A bone awl is just as effective as a wooden one (maybe more so). Lots of tools are made from biological materials; I don’t see that using your own secretions is inherently less toolish than using somebody else’s.

  12. Hexad1’s point at #11 is well-taken – it seems a bit of a stretch to extend the meaning of tool to include the surface of the Earth but as Jerry pointed-out – the cognitive ability required is important to consider: the raptor apparently has the ability to anticipate the outcome of dropping its prey and it would have to judge the required height as well. Perhaps raptors experiment, as youngsters, learning through trial and error – and how did the bird arrive at the concept in the first place? Seagulls also engage in this behavior.
    If Jane Goodall’s broad definition of tools becomes accepted, we’re going to have to qualify our term(s) whenever we discuss tools or tool-use. Could a tree branch, thrown by a chimp, to chase a snake away, be considered another example of tool use by chimps? Do the found objects that bower birds use to decorate their bower, to attract a mate, qualify as tools? And does it matter whether or not the behavior is innate – the bird certainly appears to be evaluating the possible effectiveness of his work as he walks about looking at it and re-arranging it. Is he considering it from a female’s perspective or is there some innate “correctness” that he’s compulsively striving towards?

    1. As for the chimp throwing things, I would suggest repeated use.

      One wildlife park here [Sweden] IIRC has or had an ape that collects rocks into piles to later throw at visitors when he/she gets bored. That is IMHO a tool for a set purpose. OTOH that wasn’t to fulfill an “immediate goal” but a future “desire”.

  13. When I first read about this sort of behaviour last year in Practical Fishkeeping (reporting on Lukasz Pasco of the University of Wroclaw in Poland’s paper, Tool-like behavior in the sixbar wrasse, Thalassoma hardwicke, I found myself surprised by the fact it was news. My moon wrasse (Thalassoma lunare) often engaged in the same behaviour to break up large foods. Here’s a poorly shot video of her:


    So I had the same genus performing the behaviour. Add the tuskfish, and you have three species of wrasse doing it.

    I’ve never noticed similar behaviour in the other species in my collection, including other Great Barrier Reef fish as well as African cichlids.

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