4/6/10

Great white shark amazes scientists with 4,000-foot dive into abyss, by Pete Thomas

A great white shark known to frequent New Zealand waters has given new meaning to the term "Down Under."

Scientists revealed that the 15-foot shark they've named "Shack" probed to 1,200 meters, or 3,937 feet, as it traveled across open ocean.

Malcolm Francis, principal scientist in charge of the tagging study, is calling this "the world's deepest great white shark dive record" and said it extends the predators' known vertical range by about 600 feet--which is substantial given that great whites, until fairly recently, were regarded as coastal predators.

If placed into perspective Shack might as well have been swimming upward into outer space: That's how bizarre the marine universe is at the depth to which the shark delved.

It passed through the Mesopelagic Zone (600-3,300 feet), also referred to as the "Twilight Zone," and continued well into the Bathypelagic Zone (3,300-13,000 feet), or the "Midnight Zone."

This is the realm of alien-like sea jellies and squids. It's also home to monster-like, needle-toothed predatory fishes and eels that utilize bioluminescence for light and have spawned nature TV specials and, subsequently, nightmares.

What was Shack doing in the company of viperfish, hatchetfish, dragonfish, sabertooth fish, fangtooth fish and gulper eels?

Unfortunately, nobody knows with certainty. Scientists at New Zealand's National Institute of Water & Atmospheric Research did not address this in a five-year study that also tracked the country's white sharks migrating to warmer areas during the winter.

However, a Southern California-based researcher, who has tracked great whites to about 3,000 feet, believes they're searching for food at deep-water haunts. The chief food source would be various squid species, including the fabled giant squid, whose epic battles with sperm whales are legendary.

Michael Domeier, who runs theMarine Science Conservation Institute in Fallbrook, has offered this theory based largely on anecdotal evidence.

His study has tracked white sharks from Guadalupe Island off Mexico to a vast, mid-Pacific area between Baja California and Hawaii. A similar tagging effort at the Farallon Islands west of San Francisco has followed white sharks to the same spring-and-early-summer habitat.

In this area there is little productivity. However, scientists have seen squid there, and they've encountered sperm whales, which might imply a squid-based ecosystem far below the surface. Domeier's crew also found a giant squid carcass that had been chewed on.

Though other scientists do not qualify this as proof, the theory is not far-fetched (there are giant squid off New Zealand, too). And as for possible encounters between great whites and giant squid, that's a TV special the "Shark Week" producers at the Discovery Channel ought to be working on without delay.

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