June 1, 2009 | David F. Coppedge

Protein Springs Keep Crabs Happy

Crabs and crayfish contain “exquisite” protein springs around their mouth parts that enhance motion, signaling, and sensing of their environment, Science Daily reported, about work done at the University of Cambridge.
    The protein involved, called resilin, is almost perfectly elastic.  “The exquisite rubbery properties of resilin are known to be put to use as energy storage mechanisms in jumping insects and as biological shock absorbers in many animals,” said Malcolm Burrows, who conducted the study.  Using just one muscle, crabs and crayfish can move little feet (maxillipeds) around their mouth parts to deflect water currents coming out of the gills.  The resilin springs the maxillipeds right back. 

Burrows suggests that the use of resilin springs can have two cost saving advantages.  First, by saving the space that would be required for a muscle to do the job of ‘resetting’ the movement, the resilin spring allows the muscle that generates the power stroke to become larger and hence more powerful.  Second, the amount of nervous control required can be reduced because one direction of movement is controlled automatically by a spring.  As a result of this natural engineering, these limbs of the crab Carcinus maenas can beat in a coordinated way at a remarkable 20 times a second.

The movement of the maxillipeds helps the crab sense whether the gills need cleaning, and also controls the flow of odorant molecules crabs use to communicate with other members of their species.  For an example of elastic springs in a jumping insect, see the 08/01/2003 entry.

Did the crab engineer this itself?  Of course not.  Did a blind, mindless, directionless process do it?  Get real.  This scientist had no need of that hypothesis, nor should anyone else.
Research project:  What is the amino acid structure of resilin?  What is the gene that encodes it?  How much variation exists in resilin genes between crabs and insects?  What is resilin’s distribution in the animal kingdom?  Look up resilin on the web and you will find interesting articles like these at BioMed and Nature

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