A recent paper by Dickerson et al. in PNAS explains how mosquitoes are able to fly effectively in rainy conditions (remember: many of them hail from humid tropics), even though a single raindrop by weigh 50x what a mosquito weighs. If you cannot access the full paper, feel free to read this summary on BBC (complete with video).
Essentially the answer comes down to poor momentum transfer by water droplets to the flying mosquitoes. The insects have a hydrophobic surface, and most rain drops only score glancing blows, so the water slides off quickly before it can affect the flight path a great deal. Even direct hits only drop the mosquitoes a short distance, because very little of the momentum actually transfers to the ultralight mosquito - the water basically briefly engulfs them and then continues on its way. The expanded surface area for wetting on the wings produced by the fringed hair margin mosquitoes possess further improves their ability to shrug off water strikes.
This manuscript answers one intriguing question, but raises some new interesting questions about aerial stability in small insects and body shape effects during flight in adverse conditions.
It even inspired a comic strip.
Showing posts with label Fluids. Show all posts
Showing posts with label Fluids. Show all posts
Friday, June 29, 2012
Monday, May 21, 2012
KLI
Another in the series of abstracts. This was my abstract for the think-tank conference at the Konrad Lorenz Institute in Vienna, Austria in September 2010. These are invite-only sessions on various hot topics related to evolutionary biology. Ours was on the "Constraints and Evolution of Form" - basically an Evo Devo related gig. I was the resident biomechanist for this one.
Emergence of convergent forms under fluid load in plants and animals
Very few biomechanists examine both plants and animals in parallel, apparently under a tacit assumption that the rules of shape determination must differ substantially between such distantly related groups. However, convergent structures suggest that the rules of shape governing these groups are largely the same. Such similarities suggest that environmental constraints are important in determining shape, and/or that genomes are more plastic and prone to morphological convergence than often accepted. I suggest that reference to physical first principles should be made whenever shape is examined in multi-cellular organisms, regardless of their phylogenetic position. As a case example, I report on the presence of highly convergent structures related to resistance and passive yield under aerodynamic fluid load in plants and animals. I utilize examples from both living and fossil forms, including broad-leafed trees, neornithine birds, and azhdarchid pterosaurs.
Emergence of convergent forms under fluid load in plants and animals
Very few biomechanists examine both plants and animals in parallel, apparently under a tacit assumption that the rules of shape determination must differ substantially between such distantly related groups. However, convergent structures suggest that the rules of shape governing these groups are largely the same. Such similarities suggest that environmental constraints are important in determining shape, and/or that genomes are more plastic and prone to morphological convergence than often accepted. I suggest that reference to physical first principles should be made whenever shape is examined in multi-cellular organisms, regardless of their phylogenetic position. As a case example, I report on the presence of highly convergent structures related to resistance and passive yield under aerodynamic fluid load in plants and animals. I utilize examples from both living and fossil forms, including broad-leafed trees, neornithine birds, and azhdarchid pterosaurs.
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