Scientists discover Grouper and Moray eels team up to hunt fish

[occrider]

A Fishy Tag-Team
By Jennifer Cutraro
ScienceNOW Daily News
7 December 2006

Superstar wrestlers Hulk Hogan and Macho Man Randy Savage may have perfected the art of tag-teaming, but the benefits of the technique extend well beyond the wrestling ring. According to a new study, two unrelated species of coral reef fish communicate with each other to hunt jointly, improving their success. By combining their complementary hunting strategies, groupers and moray eels leave their prey with nowhere to hide.
Groupers are large predatory fish that hunt smaller fish in open water. Moray eels, on the other hand, slither through crevices in coral reefs and rocky substrates, nabbing the fish hiding from open water predators—such as groupers. Marine biologists have previously observed that groupers will sometimes follow moray eels and eat the fish they flush out from the reef's nooks and crannies. But nobody suggested that they talked about it first.

Yet that's just what behavioral ecologist Redouan Bshary of the University of Neuchâtel in Switzerland saw happen. While observing an individual grouper in his Red Sea field site, Bshary noticed the grouper swim right up to a moray eel tucked away in the reef and begin shaking its head. What Bshary observed next took him completely by surprise: The moray eel came out of its hole, and the two fish swam away together.

Bshary and his colleagues then studied a population of groupers and moray eels in a saltwater coral reef in Egypt's Ras Mohammed National Park. The researchers found that the head-shaking behavior entices an eel to come out of its hole and join the grouper, and that hungry groupers who have been unsuccessful on a solo hunt are more likely to recruit an eel as a hunting partner than satiated groupers are. They also observed that when groupers chased prey items into the reef, they would perform a "headstand" above the prey item's location and twitch their heads back and forth; in response, eels would swim to the location and enter the reef, trying to nab the tasty morsel for themselves.

In all, working with moray eels improved grouper hunting efficiency five-fold, the team reports in the current issue of PLoS Biology. Eels swimming with groupers also caught prey items, but the team did not observe any solitary eels catching prey and therefore could not gauge a change in their efficiency. The researchers report, however, that eels traveling with groupers are even more efficient hunters than the groupers are, capturing nearly twice as many prey items per hour.

Ecologist Chris Stallings Oregon State University in Corvalis cautions that this is not the first study to document groupers and eels hunting together, but he acknowledges the signaling behavior that initiates the tag-team between the two fish is "novel and exciting." Biologist Craig Packer of the University of Minnesota in St. Paul adds that the study shows that animals don't need big brains to cooperate. Many ecological models of cooperation between individuals are complicated, requiring long-term memory of different individuals, he says. But in this system, he says, a grouper just needs to find any old eel.

http://sciencenow.sciencemag.org/cgi/content/full/2006/1207/2

 

[Codyjp]

that is really cool stuff!

 

[shoupart]

Wow! That is such a cool discovery! Who would have thought there would be such a symbiotic relationship between the two creatures?!
I like the bit about the grouper communicates. Great stuff!

 

[drbill]

When I first read of this finding, it was billed as the first observation of cooperative hunting between two unrelated species. I posted on the site where this was stated saying that I was 99.99% sure there were scientific papers describing other examples of cooperative hunting behavior.

However, as pointed out in this article, the signalling between the two species is quite interesting.

I've been interested in communication between unrelated species ever since one of my marine biology students observed and documented such behavior between an ocean sunfish (Mola mola) and a Heerman's gull (Larus hermannii?) back in the early 70's. In that case the sunfish was soliciting cleaning by the gull.

 

[T-Dog]

Here's another interesting story on cooperative fishing between two species.

A dolphin-human fishing cooperative in Brazil.
Pryor, K; Lindbergh, J; Lindbergh, S; Milano, R
Marine Mammal Science. Vol. 6, no. 1, pp. 77-82. 1990.

In the town of Laguna, in the state of Santa Catarina near the southern tip of Brazil, a cooperative fishing method has arisen between local fishermen and members of an apparently resident population of bottlenose dolphins, Tursiops truncatus . The cooperative fishing occurs primarily on the shores of the inlet from the ocean to the lagoon, near the center of town. The authors observed this fishing during 3-6 April 1988, and 15-18 February 1989. During our visits typically 30-40 fishermen and one to four dolphins were present in the principal fishing location throughout the daylight hours.

Descriptors: interspecific relationships; social behaviour; cooperatives; marine mammals; fishermen; man; Tursiops truncatus; Brazil

 

[beejw]

Wow. that is totally amazing!!

i would just point about however, to shoupart, just FYI, that this is not a "symbiotic" relationship, such as the one between anemone and cleaner shrimp, or algae/cynobacteria and fungi, which form lichen.

 

[Crawl79]

That is cool, I wonder if anyone has any video evidence of this tag team in action.

 

[fbosch]

I was in Turks and caicos and saw and filmed a nassau grouper and a moray doing this and after they sort of cuddled and nuzzled each other, actually physically touching. I think it's called shadow feeding. I also saw yellow snappers shadowing sting rays there on a sand bar.

 

[Phenol]

It is very cool. Unfortunately I've never observed this. Humann and DeLoach call it nuclear hunting (rather than symbiosis). Their 1999 Reef Fish Behavior: Florida, Caribbean, Bahamas has a few pictures and descriptive text of coneys (Epinephelus fulvus), graysbys (Epinephelus cruentatus) and various species of morays hunting together. In these instances, the small grouper initiated the cooperation, but the moray led the hunt.

 

[Charlie99]

I was in Turks and caicos and saw and filmed a nassau grouper and a moray doing this and after they sort of cuddled and nuzzled each other, actually physically touching.

I've seen this sort of cooperative type of hunting in both Cozumel and Maui. The nuzzling I've noticed was kind of a resynchronization after going through one coral head. The eel would come out, and just kind of hang until one of the groupers or jacks came up alongside, facing the same way and nuzzled or brushed it. Only then would the eel head on over to the next coral head. Then the eel would stop just short of the next coral head, waiting for the groupers or jacks to position themselves.

What I found particularly interesting is that the grouper/eel interaction in Cozumel and jack/eel interaction in Maui were very similar, even though they were different species of eels and fish in the two locations.

I've never been lucky (or alert) enough to see the initiation sequence reported in article linked in the originating post. Now I'll be watching to see if peacock groupers and jacks in Maui do the head shaking and head stand to get eels to come out and hunt with them.