Adelie penguin chicks in Antarctica, with MS Explorer in the background. (Photo: Brocken Inaglory)
Video reveals penguins' technique to devour krill
Tuesday, January 29, 2013, 04:20 (GMT + 9)
Japanese researchers say Antarctica’s Adelie penguins (Pygoscelis adeliae) are great hunters who catch their prey efficiently and by surprise.
"You could say the penguins have an amazing stealth mode," said Yuuki Watanabe, a researcher at Japan's National Institute of Polar Research. "They're great at sneaking up on their prey and taking them unaware."
This week, Watanabe released footage from December 2010 showing a penguin hunt for fish and krill. The footage was obtained by attaching tiny cameras -- "penguin cams" -- strapped to the backs of 15 penguins, and which automatically switched on when a penguin entered the water and recorded for 90 minutes, Reuters reports.
He explained that while foraging is the most basic activity of animals, details of foraging behaviour, especially in marine animals like penguins, remain largely a mystery, BBC reports.
"The krill wiggle their bodies about, they clearly make an attempt to swim off at full speed to escape," Watanabe said. "But that doesn't make the slightest difference to the penguins. They just gobble up the krill that are trying to get away and swallow them whole."
The data offers a look at the foraging patterns of these penguins and gives future researchers a way to study other penguins’ eating habits. The findings were published in the Proceedings of the National Academy of Sciences.
In addition to the cameras, the research team used two accelerometers strapped to each bird that measured its head and body movements to calculate how fast it ate the fish and krill.
"We did not really know if the penguins caught krill one-by-one. I had thought that maybe they just got into their stomachs when they were after some other prey," Watanabe said.
"But when we saw the footage it turned out the penguins were doing just that, eating these tiny little creatures one after the other," he continued.
The team also realized that instead of swimming in random patterns, the penguins hung poised on the edge of the ice until a thick swarm of fish or krill approached, and only then dived in to the water for the hunt.
According to the footage, the krill killing-rate was quick and efficient, allowing the penguins to consume an average of two krill per second when the krill were attacked while clustered in swarms -- a much faster rate than under usual hunting conditions.
“No unsuccessful attempt of prey capture was observed in any individual birds,” the team wrote. Watanabe’s plan now is to repeat the experiment with sharks.
By Natalia Real