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Lecture 9, Feb 1, 2011

Lecture 9, Feb 1, 2011. Flea jump continued Levers. Rothschild, M. et al. 1973. The flying leap of the flea. Scientific American 222: 92-101. Rebound resilience of the protein resilin is 97% Bubonic plague flea: 1-2 mm long jumps 90 mm high 6’ human to 300 feet

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Lecture 9, Feb 1, 2011

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  1. Lecture 9, Feb 1, 2011 Flea jump continued Levers

  2. Rothschild, M. et al. 1973. The flying leap of the flea. Scientific American 222: 92-101

  3. Rebound resilience of the protein resilin is 97% Bubonic plague flea: 1-2 mm long jumps 90 mm high 6’ human to 300 feet Flea can jump >50 X its body length Accelerates from rest to 1 metre p sec in a distance of 0.4 mm; extends its legs in about 8/1000 th of a second. Power rate of doing work Resilin located in the pleural arch Energy loaded into pleural arch and held there by catches Release is by body width change.

  4. The trochanteral depressor is located a relatively long way from the trochanter; it originates on the notum and inserts on the trochanter (B, C). The insertion is via a massive tendon-like apodeme and this attaches anterior to the (dicondylic) axis of the trochanteral rotation (see blue dots in A, B, C). So the contraction of the trochanteral depressor pulls the trochanter, rotating it forward on the coxa and extending it (= depressing it) against the substratum.

  5. An antagonist of the trochanteral depressor is the levator of the trochanter. It originates on the inner wall of the coxa and inserts on the trochanter posterior to the axis. And another muscle antagonistic to the trochanteral depressor is the epipleural muscle: this inserts on the base of the coxa and on its contraction, as with the levator, pulls behind the axis of rotation of the trochanter on the coxa. Both the epipleural muscle and the levator of the trochanter have the effect of flexing the limb, i.e. raising it from the substratum.

  6. Under normal locomotory movement either the levator or the depressor is contracting: they are not active at the same moment. But in preparing itself in the jumping position, the flea eventually contracts all three muscles simultaneously.It begins by flexing the limb (the levator and epipleural muscles playing an appropriate part in this). Then all three muscles [levator of trochanter, epipleural muscle and depressor of the trochanter] are contracted simultaneously. Since the depressor opposes the action of the other two, nothing happens now to change the relation of the segments of the flexed hind limb. Rather the force expended by the muscles is "loaded into the pleural arch", i.e. it goes to compress the resilin pad located above the pleural plate, squeezing the resilin between the plate and the notum.

  7. Some animals have two valves but are not Mollusca, e.g., lampshells Bivalve (Mollusca) body Orientation paleo.cortland.edu Museum of New Zealand Lampshell [Brachiopoda] Discovering Fossils Venericor bivalve

  8. Dragonfly flight muscles Photo from ‘Creative Lynx’

  9. SaltatorialadaptationAn unnamed Myopophyllum sp. of katydid from Ecuadorhind femur bears defensive spines: these legs are weapons as well as a device for rapid escape [see species on webpage home: it is the same genus]

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