Related Experiment Video
Updated: Jul 11, 2026
06:24
Individual Culturing of Tigriopus Copepods and Quantitative Analysis of Their Mate-guarding Behavior
Published on: September 26, 2018
The need for speed. II. Myelin in calanoid copepods
T M Weatherby1, A D Davis, D K Hartline
1Biological Electron Microscope Facility, Pacific Biomedical Research Center, University of Hawaii at Manoa, Honolulu 96822, USA.
Journal of Comparative Physiology. A, Sensory, Neural, and Behavioral Physiology
|May 8, 2000
Summary
Myelinated axons, crucial for rapid nerve impulse conduction, are widespread in calanoid copepods. Their unique myelin structure, unlike vertebrates, features continuous lamellae and focal nodes, speeding neural signaling.
Area of Science:
- Neurobiology
- Invertebrate Zoology
- Cell Biology
Background:
- Myelin sheaths significantly increase nerve impulse conduction speed.
- Myelinated axons are common in vertebrates but rare in invertebrates.
Purpose of the Study:
- To investigate the presence and structure of myelinated axons in calanoid copepods.
- To compare copepod myelin with that of other animal groups.
Main Methods:
- Utilized electron microscopy with rapid cryofixation techniques.
- Examined myelin structure in sensory and motor axons and interneurons.
Main Results:
- Confirmed widespread myelinated axons in calanoid copepods, with sheaths up to 60 layers thick.
- Described unique myelin features: continuous circular lamellae, complete cytoplasm exclusion, and focal/fenestration nodes.
- Observed myelin lamellae fusing with the axolemma or adjacent lamellae at nodes.
Conclusions:
- Copepod myelin shares functional similarities with vertebrate myelin in minimizing current flow for faster nerve conduction.
- Copepod myelin exhibits a unique structure, differing from all previously described groups while incorporating features from various ones.
