Title:
Ant Rafts and Other Water Repellent Systems
Ant Rafts and Other Water Repellent Systems
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Author(s)
Hu, David L.
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Abstract
We present a series of experiments demonstrating the water-repellent adaptations of a
range of animals, from insects to mammals. These adaptations are necessary for survival in
rain and other wet environments. During flash floods, fire ants weave hydrophobic rafts with
their own bodies in order to keep their colonies dry. We discuss their method of
self-assembly and present a model that predicts their construction rate. To survive raindrop
impacts, flying insects take advantage of their low mass, which prevents drops from
splashing on them. The resulting impact force on flying mosquitoes is 100-300 gravities,
quite possibly the largest in the natural world. For such small insects, small size is
advantageous in rain. If an animals is large, active mechanisms must be employed to shed
water. Mammals of all sizes can shake off 70% of the water on their bodies in fractions of a
second. We show that wet mammals shake at tuned frequencies to dry and present a
scaling law relating animal size and frequencies required to dry. In this talk, the audience
will learn the basics of modeling and experimentation with surface-tension phenomena.
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Date Issued
2012-04-10
Extent
61:54 minutes
Resource Type
Moving Image
Resource Subtype
Lecture