SCIENCE

"By examining fossils and ancient sediment on the sea floor, we can see that something very unusual happened to the Earth's carbon cycle," said Ken Caldeira, a senior scientist at the Carnegie Institution's Department of Global Ecology. "Our carbon dioxide emissions are risking biological, chemical and climate changes of a magnitude that has not been seen in more than 50 million years."

-- Juliet Eilperin

Fish Can Team Up to Trap Prey

Can fish cooperate as they hunt for food, with one species flushing out prey that another then captures and eats?

This provocative possibility is raised by the unusual case of the grouper and the giant moray eel. The two live alongside each other in the Red Sea and, according to a study in the Public Library of Science/Biology, they sometimes act as a one-two punch as they hunt the coral reefs.

The moray eel hunts in the crevices of the reefs, since its long, thin body can slide into narrow spaces. The grouper hunts in open waters around the reef and can keep fleeing prey from escaping. The result is that the two together can flush and trap prey better than each could on its own.

Using snorkels to follow the fish for up to three hours at a time, Redouan Bshary of the University of Neuchatel in Switzerland found that groupers and eels spent more time together than would be expected by chance and did appear to hunt together. Bshary also found that groupers seemed to actively recruit moray eels through a curious head shake they made close to the eel's head, which resulted in the eel coming out of its crevice.

Those previously unknown head shakes especially intrigued the researchers. "The simplest explanation," they wrote, "is that these signals indicate only the motivation of the grouper to engage in hunting, which then becomes positively associated with hunting success for the moray eels."

-- Marc Kaufman