Thursday, March 11, 2010

A Jellyfish sting is something like being shot by bullets - and about as fast

...the process takes 700 nanoseconds (billionths of a second).

SHOOT: No wonder their stings are so feared, and so painful.
Holstein’s team has used an ultra-high-speed electronic framing-streak camera to measure the kinetics of nematocyst discharge. Because the camera records over 1.4 million frames per second, its resolution was high enough to capture the discharge of Hydra nematocysts, and to determine that the process takes 700 nanoseconds (billionths of a second).
During discharge, Hydra nematocysts studied create an acceleration of up to 5.4 million g, and exert a pressure of more than 7 giga-Pascals, on a par with some types of bullets. Holstein and his team believe that the high speed and pressure generated during nematocyst discharge are created by thesudden release of energy stored in the stretched collagen-polymer wall of the nematocyst.
Hox genes control axial patterning
A mutation in the fruit fly antennapedia gene, for example, results in the development of a leg in place of an antenna, because the patterning of the antero-posterior axis has been disrupted.
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