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Sunday, July 25, 2010

Dem Bones, Dem Bones, Dem Jawbones

A new study points to an adaptation that allows rorquals, the pleat-throated whales, to engorge huge amounts of food-filled sea water without snapping off their lower jaws.

When Blue Whales (Balaenoptera musculus) open their mouths to filter-feed, one keen whale observer and author noted in her recent book, it is "the biggest biomechanical event to happen on the planet." And quote possibly the biggest ever to have happened.

The subject of the study cited by Live Science was Humpback Whales (Megaptera novaeangliae), lunge-feed thousands of times a year if they're lucky.

The research involved a type of X-ray technology called quantitative computed tomography, or QCT. Writes Live Science's Clara Moskowitz:

The scientists discovered that humpback whale mandibles are shaped in a unique way, different from the mandibles of humans and right whales -- the only other species for which QCT data is available.

In particular, the scientists measured a feature called flexural rigidity -- a combination of high bone density and large cross-sectional area that allows a bone to resist bending. The researchers found that humpback whales' jaws are formed with a unique pattern of flexural rigidity -- highest at the edges attached to the skull, and lowest at the center -- that is optimized to resist the strain from lunge feeding.

It's like a high-performance tennis racquet, in a way. With a sweet spot for krill.

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