03_FleaJump - Flea Jump page 1.01 RR Lew Flea Biology How...

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Flea Jump – page 1.01 – RR Lew How high can a flea jump? About 20 cm or so, similar to the height that a human can jump. The real question is why do humans and fleas (and other organisms) all jump to approximately the same height. This is what will be explored in this lecture. Why choose a flea? Well, they are famous jumpers. The typical ‘WOW’ factor is that they jump many times their own height, while we cannot. And, they are deadly as vectors of a number of diseases, of which the Plague is only one example. The larvae feed on detritus that might be found in a house, including the sloughed skin from animals (such as humans). The adults feed mostly on blood. The mouthparts shown below in the scanning electron microphotograph give a sense of how they will chew through what is for them the thick protection of skin, to reach blood vessels for their feast. When their feast is complete, they are engorged, as shown in the CDC microphotograph below. Flea Biology Male Xenopsylla cheopis (oriental rat flea) engorged with blood. This flea is the primary vector of plague in most large plague epidemics in Asia, Africa, and South America. Both male and female fleas can transmit the infection. from the CDC Centers for Disease Control and Prevention website. Divison of Vector-Borne Infectious Diseases. Plague (”Plague is an infectious disease of animals and humans caused by a bacterium named Yersinia pestis.”) The head of a flea. A scanning electron micro- graph from The Micro- Environmental Imaging and Analysis Facility at the University of California, Santa Barbara.
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Flea Jump – page 1.02 – RR Lew Trajectories of a flea jump (as well was trajectories of spores released from fungi) are shown below [1] . Organismal Leaps The data have been normalized to maximal distance (the normalized y-scale is expanded 2-fold relative to the x-axis). The absence of a ‘well-behaved’ parabolic trace (well known in Introductory Physics textbooks) is due to the effect of air resistance to flight. [1] Source: Vogel S (2005) Living in a physical world. II. The bio-ballistics of small projectiles. Journal of Biosciences. 30:167–175 Bio-ballistic data for various insects and spores. Landing speeds assume launch at the angles that maximize horizontal range and equal launch and landing elevation [1] . Data for a basketball are shown for comparison. Effective Launch Landing Launch Best Maximum Range loss diameter speed speed Reynolds launch range from drag Projectile (mm) (m s –1 ) (m s –1 ) number angle (m) (%) Desert locust 10.0 3.0 2.8 2,000 44º 0.85 6.1 Rabbit flea 0.5 4.0 1.0 130 30º 0.3 80.8 Pilobolus 0.3 20.0 1.1 400 17º 0.82 98.0 Sordaria spore 0.04 30.0 0.05 23 0.06 99.96 Basketball 240.5 20.0 18.0 320,000 41.5º 35.7 12.3
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Flea Jump – page 1.03 – RR Lew
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This note was uploaded on 10/25/2010 for the course BIOPHYS 2090 taught by Professor R.r.l during the Fall '10 term at Maple Springs.

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03_FleaJump - Flea Jump page 1.01 RR Lew Flea Biology How...

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