Certainly, the groupers are five times more successful at catching prey if their partners are around. Only one of the two predators will grab any individual prey, but both have a greater chance of eating if they work together. When the moray dives in, the fish has two options: stay and be eaten by the eel, or flee and be picked off by the grouper. ![]() When both species hunt together, nowhere is safe. The groupers are open-water specialists, but the morays can probe in cracks and crevices. The two species have complementary hunting skills. The groupers lead the eels to a place where prey are hidden, and signal the right spot with more head-shaking the morays investigate. Bshary found that they were less likely to recruit morays if they’d just been fed, but more likely if they had just chased a prey fish into an inaccessible crevice. The groupers trigger the alliance if they’re hungry or frustrated. The signal is a call to arms, rousing the lazing morays to leave their crevices and swim off with the groupers. Bshary saw that the groupers would visit the morays in their resting places and vigorously shake their heads. “I followed groupers to see how they interact with several cleaners in a row, and I observed them signalling towards the morays,” he says. Again, this discovery was the result of his work with the cleaner wrasse. ![]() In 2006, he described an equally remarkable alliance between two formidable predators: the giant moray eel and the roving coral grouper. This is the second time that Bshary has observed Red Sea fish hunting in teams. They’re the only known species of fish where different individuals assume specific roles, not unlike hunting wolves, lions or chimps. But the goatfish are more sophisticated still. Until now, the most sophisticated example was an African elephantfish that flushes out its prey in tight formations, and communicates with one another using electric pulses. Many species of fish will attack the same prey, but very few truly work together during a hunt by coordinating their attacks. Steinegger has started to test captive goatfish and he has duplicated the same coordinated hunts in the controlled conditions of a lab. Once the chaser drives its prey into coral crevices, the others act as blockers, swimming around to cut it off. The moment one fish shoots off towards a target, the others join in the hunt. They only team up when they hunt among corals. ![]() The goatfish normally forage alone, using their whisker-like barbels to feel around for prey buried in sand. They could belong to several different groups, but those groups would keep the same members over time. Each fish would regularly keep in touch with the same companions, usually ones of similar size. Eventually, she could tell 17 different individuals from one another, and she learned that they form surprisingly stable social networks. After repeatedly snorkelling after the fish, Strubin gradually learned that they have distinctive spots on their bodies and blue lines around their eyes. “During that time, one happens to see a lot of things.” The cooperative hunts of the goatfish were one of these incidental observations. “I spent a long time working on cleaner wrasses ,” he says. Bshary has spent over a decade in the Red Sea, studying the local fish. The goatfish are one of the few examples of fish that hunt in groups, and their strategy has just been described by Carine Strubin, Marc Steinegger and Redouan Bshary from the University of Neuchatel. With no escape, the predators – a group of yellow saddle goatfish – close in on their prey. ![]() One of them chased it into a coral crevice, while the others circled around to block off any exists. In the Red Sea, a tiny fish has been cornered by a group of hunters working as a team.
0 Comments
Leave a Reply. |