Magazine article Science News

Hidden Depths: Antarctic Krill Startle Deep-Ocean Scientists

Magazine article Science News

Hidden Depths: Antarctic Krill Startle Deep-Ocean Scientists

Article excerpt

[ILLUSTRATION OMITTED]

Biologists looked into the abyss and the abyss looked back, with lots of little compound krill eyes.

The shrimplike Antarctic krill, a major player in polar ecosystems, is supposedly a creature of the upper ocean. Yet the first science cruise to lower a camera to the abyssal seabed of the Southern Ocean off Antarctica found what looked like krill 3,000 meters down, says Andrew Clarke of the British Antarctic Survey based in Cambridge, England.

The cruise, during the South Pole summer of 2006-2007, inaugurated the United Kingdom's remotely operated, camera-carrying Isis vehicle. Clarke says that he and several other biologists were just piggybacking on a mission primarily designed for glaciologists and geophysicists to examine the deep continental slope and seabed beyond.

By that time of year, photosynthesizing plankton have multiplied in a great burst at the surface of the ocean and drifted down. When the scientists lowered their camera to the sea bottom, they saw a layer of still-green plankton-fall--and the krill feeding on it. These animals were the classic Antarctic krill species, Euphausia superba, say Clarke and Paul Tyler of the National Oceanography Center in Southampton, England, in the Feb. 26 Current Biology.

The Antarctic krill species matures to 6 centimeters in length, a giant among krill kind, and its red markings show up in the Isis video. The animals, including females ready to spawn, even made nose-dives into the sediment, a behavior seen in shallow water that sends up puffs of fallen plankton. …

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