A check of my animal physiology books shows a top nerve transmission speed
of 100 m/sec in a shrimp nerve fiber. Giant nerve fibers in the polychaete
Myxicola conduct at about 20 m/sec. Lumbricus is listed at 11.3 m/sec in
one reference and 30-38 m/sec in another. It seems the important variables
are diameter and myelination. Myxicola has the former but not the latter,
whereas oligochaetes apparently have large diameter axons with a
myelin-like outer sheath. Check Prosser, Comparative Animal Physiology,
volume on Neural and Integrative Animal Physiology.
Best,
Les.
At 08:45 PM 3/29/2002 +0000, James Mahaffy wrote:
>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.
Les Watling
Professor of Oceanography and
Pew Fellow in Marine Conservation
Darling Marine Center
University of Maine
Walpole, ME 04573
Phone 207-563-3146 x248
Fax 207-563-3119
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