Natures wonders: seabirds dive safely at 50 MPH (Introduction)

by David Turell @, Thursday, October 06, 2016, 01:45 (1075 days ago) @ David Turell

A study shows that body and head design are perfect for such speeds:

http://phys.org/news/2016-10-birds-safely-high.html

"In a new study published in the Proceedings of the National Academy of Sciences, Jung and his coworkers investigate the biomechanics of gannets' dives. They found that the birds' head shape, neck length and musculature, and diving speeds work in concert to ensure that the force of the water doesn't buckle their slim necks.

"Previous studies of the diving birds have focused on ecological aspects of this hunting behavior, called "plunge diving." Jung's is the first paper to explore the underlying physics and biomechanical engineering that allow the birds to plunge beneath the water without injury.

"To analyze the bird's body shape and neck musculature, the team used a salvaged gannet provided by the North Carolina Museum of Natural Sciences. They also created 3-D printed replicas of gannet skulls from the collection at the Smithsonian Institution, which helped them measure the forces on the skull as it enters the water.

"The primary force acting on the gannet's head as it plunges beneath the water is drag, which increases with speed. To analyze what other parameters affect the force the bird experiences, the researchers created a simplified model from a 3-D printed cone on a flexible rubber "neck," and plunged this system into a basin of water, varying the cone angle, neck length, and impact speed. High-speed video showed whether the neck buckled.

"Their analysis revealed that the transition from stability to buckling depends on the geometry of the head, the material properties of the neck, and the impact speed; at typical gannet diving speeds, the birds' narrow, pointed beak and neck length kept the drag force in a safe range.

"What we found is that the gannet has a certain head shape, which reduces the drag compared to other birds in the same family," Jung said.
The researchers also discovered that the birds further reduce the risk of buckling by contracting their neck muscles before impact, straightening the S-shaped neck."

Comment: Nature keeps it record of showing us great living designs. If this was developed by birds trying it out, only the successful survivors would gradually improve the design. Seems unlikely, and again saltation has to be considered.


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