DATELINE: 1 May, 2002

PENGUINS HAVE PERFECT DIVE PROFILES
Scientists studying the swimming techniques of penguins have discovered that the birds deliberately slow their ascent from a dive, following the same profile that a human diver would use to avoid decompression illness.
Researchers at the National Institute of Polar Research were conducting a study into how penguins can make deep dives on a lungful of air and avoid the bends. Marine mammals such as whales and seals collapse their lungs before a dive, avoiding the problem of nitrogen on-gassing at depth. Penguins cannot collapse their lungs, and need to dive with a lungful of air to provide them with sufficient oxygen while underwater.
The scientists were astonished to find that penguins adopt the same ascent profiles as human divers: they stop using their flippers halfway up, and allow the natural buoyancy of their body to raise them to the surface. The birds also alter the path of their ascent to an oblique angle, enabling them to spend significantly longer at more shallow depths.
It may be too early to conclude that this behaviour is solely governed by decompression considerations. Penguin-spotting marine biologists from the University of California have suggested that the dive profile may also be designed to avoid predators.

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