How Do Pelicans Survive Their Death-Defying Dives? | Deep Look
2.4 میلیون بار بازدید -
7 سال پیش
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Brown pelicans hit the water
Brown pelicans hit the water at breakneck speed when they catch fish. Performing such dangerous plunges requires technique, equipment, and 30 million years of practice.
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California’s brown pelicans are one of two pelican species (once considered the same) that plunge from the air to hunt. The rest, like the white pelican, bob for fish at the water’s surface.
The shape of its bill is essential to the birds' survival in these dives, reducing “hydrodynamic drag” — buckling forces, caused by the change from air to water — to almost zero. It’s something like the difference between slapping the water with your palm and chopping it, karate-style.
And while all birds have light, air-filled bones, pelican skeletons take it to an extreme. As they dive, they inflate special air sacs around their neck and belly, cushioning their impact and allowing them to float.
Even their celebrated pouches play a role. An old limerick quips, “A remarkable bird is a pelican / Its beak can hold more than its belly can…” That beak is more than just a fishing net. It’s also a parachute that pops open underwater, helping to slow the bird down.
Behind the pelican’s remarkable resilience (and beaks) lies 30 million years of evolutionary stasis, meaning they haven’t changed much over time.
--- What do pelicans eat?
Pelicans eat small fish like anchovies, sardines, and smelt.
--- How long to pelicans live?
Pelicans live 15-25 years in the wild.
--- How big are pelicans?
Brown pelicans are small for pelicans, but still big for birds, with a 6-8 foot wingspan. Their average weight is 3.5 kg.
---+ Read the entire article on KQED Science:
https://ww2.kqed.org/science/2017/04/...
---+ For more information:
U.S. Fish and Wildlife brown pelican page
https://ecos.fws.gov/ecp0/profile/spe...
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---+ Follow KQED Science:
KQED Science: http://www.kqed.org/science
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Twitter: Twitter: kqedscience
---+ About KQED
KQED, an NPR and PBS affiliate in San Francisco, CA, serves Northern California and beyond with a public-supported alternative to commercial TV, Radio and web media.
Funding for Deep Look is provided in part by PBS Digital Studios and the John S. and James L. Knight Foundation. Deep Look is a project of KQED Science, which is also supported by HopeLab, the S. D. Bechtel, Jr. Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the Gordon and Betty Moore Foundation, the Smart Family Foundation and the members of KQED.
#deeplook
SUBSCRIBE to Deep Look! http://goo.gl/8NwXqt
DEEP LOOK is a ultra-HD (4K) short video series created by KQED San Francisco and presented by PBS Digital Studios. See the unseen at the very edge of our visible world. Get a new perspective on our place in the universe and meet extraordinary new friends. Explore big scientific mysteries by going incredibly small.
* NEW VIDEOS EVERY OTHER TUESDAY! *
California’s brown pelicans are one of two pelican species (once considered the same) that plunge from the air to hunt. The rest, like the white pelican, bob for fish at the water’s surface.
The shape of its bill is essential to the birds' survival in these dives, reducing “hydrodynamic drag” — buckling forces, caused by the change from air to water — to almost zero. It’s something like the difference between slapping the water with your palm and chopping it, karate-style.
And while all birds have light, air-filled bones, pelican skeletons take it to an extreme. As they dive, they inflate special air sacs around their neck and belly, cushioning their impact and allowing them to float.
Even their celebrated pouches play a role. An old limerick quips, “A remarkable bird is a pelican / Its beak can hold more than its belly can…” That beak is more than just a fishing net. It’s also a parachute that pops open underwater, helping to slow the bird down.
Behind the pelican’s remarkable resilience (and beaks) lies 30 million years of evolutionary stasis, meaning they haven’t changed much over time.
--- What do pelicans eat?
Pelicans eat small fish like anchovies, sardines, and smelt.
--- How long to pelicans live?
Pelicans live 15-25 years in the wild.
--- How big are pelicans?
Brown pelicans are small for pelicans, but still big for birds, with a 6-8 foot wingspan. Their average weight is 3.5 kg.
---+ Read the entire article on KQED Science:
https://ww2.kqed.org/science/2017/04/...
---+ For more information:
U.S. Fish and Wildlife brown pelican page
https://ecos.fws.gov/ecp0/profile/spe...
---+ More Great Deep Look episodes:
The Fantastic Fur of Sea Otters
The Fantastic Fur of Sea Otters | Dee...
How Do Sharks and Rays Use Electricity to Find Hidden Prey?
How Do Sharks and Rays Use Electricit...
---+ See some great videos and documentaries from the PBS Digital Studios!
Physics Girl: Why Outlets Spark When Unplugging
Why outlets spark when unplugging - E...
Gross Science: Everything You Didn’t Want to Know About Snot
Everything You Didn't Want To Know Ab...
---+ Follow KQED Science:
KQED Science: http://www.kqed.org/science
Tumblr: Tumblr: kqedscience
Twitter: Twitter: kqedscience
---+ About KQED
KQED, an NPR and PBS affiliate in San Francisco, CA, serves Northern California and beyond with a public-supported alternative to commercial TV, Radio and web media.
Funding for Deep Look is provided in part by PBS Digital Studios and the John S. and James L. Knight Foundation. Deep Look is a project of KQED Science, which is also supported by HopeLab, the S. D. Bechtel, Jr. Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the Gordon and Betty Moore Foundation, the Smart Family Foundation and the members of KQED.
#deeplook
7 سال پیش
در تاریخ 1396/02/05 منتشر شده
است.
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