For the first time ever, researchers have electronically tagged sperm whales and jumbo squid swimming together off Mexico's Pacific Coast to learn more about how the giant creatures hunt and feed.
It's probably the only time tracking devices have been applied simultaneously in the same waters to deep-diving predators and their prey.
Sperm whales, one of the world's largest hunters, can reach nearly 60 feet (18 meters) in length and 57 tons (52 metric tons) in weight. They feed on enormous amounts of fish, octopi, and squid, including giant squid.
How the whales search for, detect, and capture their deep-water prey, however, has remained a mystery until now.
"No one has ever actually seen a sperm whale eat a squid, so we don't know how they manage to catch them," said William Gilly, a biologist at Stanford University's Hopkins Marine Station in Pacific Grove, California.
The new study tracked both the whales and one of their favorite foods: jumbo, or Humboldt, squid, which are found in the eastern Pacific Ocean. (Related: "Researchers Shed Light on Mysterious Jumbo Squid" [July 18, 2003].)
The study suggests that these large squid are much more plentiful than previously suspected. It also reveals that sperm whales have adapted to forage on such squid when they may be at their most vulnerable.
The findings appear in the March 12 edition of the journal Marine Ecology Progress Series. (Related photo: "Colossal Squid Caught off Antarctica" [February 22, 2007].)
Dark Depths
Sperm whales, immortalized by Herman Melville in his novel Moby Dick, are the largest toothed whales in the world. They inhabit every ocean.
The animals have a voracious appetite for squid. Researchers estimate that more than 110 million tons (100 million metric tons) of squid—equivalent to the entire annual harvest of all the commercial fisheries on Earth—may be consumed by sperm whales every year.
The predatory jumbo squid, with its powerful arms and tentacles and a razor-sharp beak, also has a fearsome reputation, garnering the nickname "red devil." It can weigh more than 100 pounds (45 kilograms) and grow six feet (two meters) long.
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