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Speedy Plankton: Myelinated Axons In Calanoid Copepods (Crustacea)

Published online by Cambridge University Press:  02 July 2020

April D. Davis ,
Tina M. Weatherby  and
Petra H. Lenz
April D. Davis
Affiliation:
Békésy Laboratory of Neurobiology, Pacific Biomedical Research Center, University of Hawai‘i at Manoa, Honolulu, HI96822
Tina M. Weatherby
Affiliation:
Biological Electron Microscope Facility, Pacific Biomedical Research Center, University of Hawai‘i at Manoa, Honolulu, HI96822
Petra H. Lenz
Affiliation:
Békésy Laboratory of Neurobiology, Pacific Biomedical Research Center, University of Hawai‘i at Manoa, Honolulu, HI96822
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Extract

Copepods are an abundant and diverse group of crustaceans. One order of free living copepods, the calanoids, are usually < 3 mm in length, planktonic, and possess very rapid escape responses. These animals dominate planktonic communities and their escape reactions contribute to their success. Although all calanoids respond to hydrodynamic disturbances with an escape jump, minimum reaction times vary among species, ranging from 1.5 to 6 msec. To help us understand the physiological basis underlying the phenomenally short reaction times we initiated a comparative study of the internal structures by using transmission electron microscopy (TEM).

Traditional chemical fixation was adequate for several species of copepods, and sensory structures were clearly shown. In these calanoids, minimum reaction times ranged from 3 msec to 6 msec and can be partially explained by giant axons, the most common way invertebrates increase the rate of conduction of nerve impulses. However, the internal structures of two copepod species, Euchaetarimana and Undinula vulgaris, were distorted (Fig. 1).

Type
Neurobiology
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 1308 - 1309
Copyright
Copyright © Microscopy Society of America

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References

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4.We thank M. Dunlap and D. Hartline for their thoughtful comments on the manuscript. This work was supported in part by NIH RCMI RR03061 and NSF grants OCE 89-18019 and OCE 95-21375.Google Scholar