[mou] FW: [mnbird] Why phalaropes spin

[Alt, Mark]

Cool stuff..

 

________________________________

From: mnbird-bounces at lists.mnbird.net
[mailto:mnbird-bounces at lists.mnbird.net] On Behalf Of Claudia Egelhoff
Sent: Monday, June 02, 2008 1:49 PM
To: mnbird at lists.mnbird.net
Subject: [mnbird] Why phalaropes spin

 

>From a recent Science magazine article:

Water-Assisted Feeding

Water molecules are attracted more to each other than they are to air.
The resulting surface tension makes it possible for water to flow to the
tops of trees (capillary action) and allows some insects to walk on
water. In a Report in the 16 May 2008 Science, Prakash et al.
<http://www.members-aaas.org/util/link.jsp?e=60tPcvGJ7sskxasyAKWhTDI7mXr
7XVINO6WkLFPBVjR6bFltLJk4xZc0zh2neLI1g&s=5xJPmfuci8kHvU7hZTSQHzg..A&v=6L
UW3rgARsjYobeDFBphjCA..A>  demonstrated the importance of this surface
tension to the feeding mechanism of long-beaked shorebirds called
phalaropes. By swimming in a tight circle on the water surface, the bird
first generates a vortex that draws underlying fluid and suspended prey
(crustaceans or other invertebrates) toward the surface. As it spins, it
dips its beaks into the water, capturing a drop of fluid and food
between the halves of the beak. The geometry of the bird's open beak
prevents suction from being used to raise the drops mouthward. Instead,
by repeatedly opening and closing its beak in a tweezering motion, the
bird moves the drop from the tip of its beak to its mouth in a stepwise
ratcheting fashion. In laboratory experiments with a mechanical beak,
the researchers showed that the beak geometry and wetting properties, as
well as the dynamics of tweezering, can be tuned to optimize transport
efficiency. Senior author Dr. John Bush talked about the work in a
related podcast interview
<http://www.members-aaas.org/util/link.jsp?e=5KErxLQrXrcG5GoBhZ1lfFvVgmv
QISo5c_8zyElXGPhJ8ZsxDLdVes_EshtJOUi8K&s=5xJPmfuci8kHvU7hZTSQHzg..A&v=6L
UW3rgARsjYobeDFBphjCA..A> , and a related Perspective
<http://www.members-aaas.org/util/link.jsp?e=47YNycy1s5_HchcZl4la_XDYZwp
1uKipWSfvuR-lHJQU.A&s=5xJPmfuci8kHvU7hZTSQHzg..A&v=6LUW3rgARsjYobeDFBphj
CA..A>  by M.W. Denny discussed how "[c]ollaboration among biologists,
engineers, mathematicians, and physicists has produced exciting advances
in our understanding of surface tension's effects in both nature and
technology."


Claudia Egelhoff
Minneapolis, MN 55405

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