Impulse conduction velocity, fastest known in the invertebrate (and vertebrate) system

Range 90 - 210 m/sec
Organism Kuruma shrimp Marsupenaeus japonicus
Reference Kusano K, LaVail MM. Impulse conduction in the shrimp medullated giant fiber with special reference to the structure of functionally excitable areas. J Comp Neurol. 1971 Aug142(4):481-94. p.481 left columnPubMed ID5111883
Primary Source Kusano, K. 1965 Electrical characteristics and fine structure of the Ku.ruma-shrimp nerve fibers (Penaeus japonicus.) Proc. Jap. Acad., 41: 952-957. & Kusano, K. 1966 Electrical activity and structural correlates of giant nerve fibers in Kuruma shrimp (Penaeus japonicus). J. Cell. Physiol., 68: 361-384.
Comments "In the preceding papers (primary sources), the unique structure and electrophysiological characteristics of the giant medullated nerve fibers in the ventral nerve cord of the shrimp (Penaeus japonicus) were described. The giant fibers display an external diameter of about 120µm, a myelin sheath thickness of about 10µm, and an axon diameter of about 10µm. Thus there is a wide gap between the axon and the external myelin sheath. These medullated giant fibers showed an impulse conduction velocity of 90-210 m/second which is the fastest known in the invertebrate nervous system." The organism is named "Penaeus japonicus" in the article. See also Hsu et al. 1996, PMID 8807532 summary: "Giant nerve fibers of the shrimp family Penaeidae conduct impulses at the velocity highest among all animal species (~210m/s, highest in mammals=120m/s)." Although note, that for mammals, BNID 108973 Table - link top entry in table, gives value of 164m/sec for pyramidal tract in cat.
Entered by Uri M
ID 110502