Dolphins 'decompress like humans'

Scientists have found tiny bubbles beneath the blubber of dolphins that have beached themselves.

The bubbles were discovered by taking ultrasound scans of the animals within minutes of stranding off Cape Cod, US.

The team's findings help confirm what many researchers have long suspected: dolphins avoid the bends by taking long, shallow decompression dives after feeding at depth.

The study is reported in Proceedings of the Royal Society B.

Many biologists believe that marine mammals do not struggle, as human divers do, with decompression sickness - "the bends" - when ascending from great depths.

In humans, breathing air at the comparatively high pressures delivered by scuba equipment causes more nitrogen to be absorbed into the blood and the body's tissues, and this nitrogen comes back out as divers ascend.

If divers ascend too quickly, the dissolved nitrogen forms bubbles in the body, causing decompression sickness.

But marine mammals such as whales, dolphins, and seals are highly adept at dealing with the pressures of the deep.
They slow their hearts, collapse the tiny air-filled chambers in their lungs, and channel blood to essential organs - like the brain - to conserve oxygen, and limit the build-up of nitrogen bubbles in the blood that happens at depth.

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