Page 30 - BBC Wildlife - August 2017 UK

Two reef predators, the
moray eel (left) and
dusky grouper (right),
have been known to
hunt together. The
partnership begins
with a head-shake.

studied in any sort of detail. The most studied strengths, per capita hunting success
of them all, the zebrafish, Danio rerio – the is higher when groupers and morays
‘laboratory rat’ of fishes – has been the subject “IN ONE VIDEO I HAVE collaborate: the eel can pursue a small fish
of over 25,000 published scientific papers, into the reef matrix, and if it should escape to
including more than 2,000 in 2015 alone. SEEN, THE PAIR LOOK LIKE open water, the grouper is waiting to pounce.
Not that we should envy them, as FRIENDS ON A STROLL; IT’S The head-shaking gesture is referential
many of these studies are invasive, and because it anticipates and creates a future
many lethal. I would prefer not to have LIKE A SCENE FROM DISNEY.” event. This is not just sophisticated fish
been a zebrafish in a study to see if these behaviour; it is sophisticated behaviour for
handsome little striped fish would pay a any non-human. So far only great apes and
cost to relieve pain. animals’ inner lives. We are in an exciting ravens are also known to do it.
To test this, a shoal of zebrafish were era of scientific inquiry that doesn’t shy In follow-up studies, captive groupers were
placed in a complex aquarium tank with away from exploring how animals think and presented with realistic, laminated moray eels
two chambers: one was dimly lit and feel. And fishes are blowing tired old biases that could be remotely controlled. Groupers
furnished with places to hide; the other clear out of the water. Consider this list of soon learned to discriminate ‘cooperative’
brightly lit and barren. Little fishes like to achievements found in fishdom: the ability eels from wayward ones, and to direct their
feel safe, and they all avoided the barren to recognise other individuals, including us head-shakes only at the cooperative models. A
chamber. They continued to do so after by our faces; cognitive mapping; referential grouper will also assume a vertical posture to
some of the subjects were injected with acid communication; observational learning; ‘point’ to the location where a fish has sought
(presumed to cause lasting pain) and others audience effects; innovation; problem refuge in the reef.
injected with saline (relatively benign). solving; tool-use; culture; and virtue. Groupers will sometimes point for over
But when the researchers dissolved a 20 minutes. And, if a nearby moray fails to
painkiller, Lidocaine, in the barren chamber, pace precludes my expanding on get the hint, the grouper may abandon her
some of the zebrafish soon began to wander all of these, but let me elaborate on post to go and retrieve the eel and guide it
over to the barren side. And you can one: referential communication. It to the right spot.
probably guess who migrated: it was the occurs between two of the largest Beyond enlightenment, our newfound
ones injected with acid. The saline group S reef predators: groupers (of several knowledge of fishes harbours a deeper
stayed put. This study elegantly refutes the species) and giant moray eels. When a coral imperative: to respect them. By and large,
persistent belief among some of us that grouper gets hungry, he may solicit help from our treatment of fishes has fallen far short of
fishes do not experience pain. Furthermore, a moray. He does this with a specific gesture respect. For centuries we have plundered the
it shows that a little fish has the wherewithal – a rapid head-shake. The moray recognises seas. In the modern era, canoes and dories
to seek out pain-relief when it’s in the offing, the signal and, if also hungry, swims off with have been replaced by giant commercial
and that she will pay a cost to get it. the grouper. In one video I have watched, the vessels: bottom-trawlers that in one pass
The zebrafish study, like the surgeonfish incongruous pair look like friends on a stroll; can wreck delicate undersea habitats that
study described earlier, illustrates the it’s like a scene from Disney, only real. took a century to form, purse seines that
innovative methods scientists devise to probe By combining their complementary may contain a hundred-thousand dead or

30 BBC Wildlife August 2017