Giant nerve fibers in annelids

James Mahaffy mahaffy at dordt.edu
Fri Mar 29 15:45:57 EST 2002


Folks,

I am a zoology teacher at Dordt College and was talking about annelids 
last lecture.  I ran across information in the second edition (1977) of 
Edwards and Lofty's Biology of earthworms (p. 105) that I think may be a 
typo.  They say that giant nerve fibers in annelids (I assume Lumbricus 
terrestris) transmit impulses at 600 meters per second.  Somehow that 
seems to be high and I wonder if it was a typo. I did a bit of researching 
other sources I have available on nerve conduction and got 35 meters 
per second.  They, however, were general web sites on nerve conduction 
not written by annelid folks and Edwards and Lofty seems to be a very 
well written source.  600 meters per second would make earthworm 
transmission the highest speed I have seen. I think long motor neurons in 
humans are only 130 meters per second.   

I would appreciate knowing if the fibers actually transmit that fast (no
wonder they are hard to grab before I go fishing).  If it is a typo,
what is the transmission speed?  

Unless you object I will share any responses with my zoology class.  I
am blind copying them and a colleague a copy of this post.  

I will try again to order the third edition of Edward's and Lofty for
our library, but I think we had difficulty getting it last time I tried.


James Mahaffy (mahaffy at dordt.edu)        Phone: 712 722-6279
Biology Department                                     FAX :  712
722-1198
Dordt College, Sioux Center IA 51250


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