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 Scientists on Monday described how a colorful fish called the
coral trout recruits moray eels to help hunt for prey, with both
ending up well fed. Aquarium experiments showed that the trout are
choosy in picking the best eel partner for the job.
The researchers noted that the trout performed as well as
chimpanzees in a 2006 study that demonstrated how these close
cousins of humans assisted one another in a food-gathering task.
The coral trout uses communicative body gestures including head
shakes and headstands to enlist eels as hunting partners.
It's an underwater dream team, with the trout possessing the speed
to chase down a fish out in the open and the serpentine moray eel
boasting a sinuous body enabling it to get at any fleeing prey that
hides in a hard-to-reach coral crevice. They join forces on
Australia's Great Barrier Reef.
Some moray eels in the wild are more helpful than others. In the
controlled environment of aquarium experiments, moray eel models
were employed to test how well wild coral trout caught for the study
could discern a good collaborator from a bad one.
One model was designed to come to the coral trout's aid and flush
out prey. The other eel model simply went the opposite direction.
The trout quickly learned which eel model was the better partner and
recruited the good collaborator three times more often, the study
found.
"This shows that a big mammalian brain is not necessarily required
to undertake these sophisticated forms of communication," said
Alexander Vail, a marine biologist and zoologist at Britain's
University of Cambridge who led the study published in the journal
Current Biology.
"Although the brains of mammals are certainly larger than those of
fish, size may not be all that matters, and we are still a long way
from a thorough understanding of fish brains and the mental
computation they may capable of," Vail added.
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Coral trout are torpedo-shaped and about 21 inches (50 cm) long.
Their body colors range from olive green to deep red and they are
covered in small bright blue spots.
The eel benefits by being able to eat the fish chased into reef
crevices by the trout. The trout benefits by being able to eat those
fish the eel fails to catch.
"Each of these large predators is out for itself in their
collaborative relationship, but they both do far better by working
together and using communication to coordinate the hunt," Vail
added. "Both predators capture roughly the same number of prey items
when hunting together."
Researchers have noted similar collaboration with eels by another
fish, the roving coral grouper. Vail said similar skills probably
exist in other animals as well.
(Reporting by Will Dunham; Editing by David Gregorio)
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