Neuromuscular Organization for "Wing" Control in a Mollusc (Clione limacina) and a Bird (Columba livia): Parallels in Design

• Published in: American Zoologist
• Main Authors: WELSFORD, IAN G., MEYERS, R. A., WILSON, D. S., SATTERLIE, R. A., GOSLOW, G. E.
• Format: Text
• Language: English
• Published: Oxford University Press 1991
• Subjects: Articles; Clione limacina
• Online Access: http://icb.oxfordjournals.org/cgi/content/short/31/4/670; https://doi.org/10.1093/icb/31.4.670

Flapping as a means of locomotion is shared by divergent groups ranging from pteropod molluscs to birds. The pteropod, Clione limacina , exhibits two modes of locomotion, slow and fast swimming. The motor units which control swimming consist of small motoneurons and relatively nonfatigable muscle fibers, while those involved in fast swimming consistof large motoneurons and relatively fatigable fibers (Satterlie et al., 1990).The pectoralis muscle of the pigeon, Columba livia , consists of two populations of muscle fibers distinguished by histochemistry and size. Cinematographic and electromyographic experiments suggest that the large fibers are used for takeoff and landing and the small fibers for level flight (Dial et al., 1988). We have employed a suite of experimental techniques similar to those used for studies of the neuromuscular system of Clione to analyze a limited sample of motor units from the pectoralis of Columba . The peak tetanic tension and contractile fatigue resistance during electrical stimulation of single alpha axons, functionally isolated from nerve filaments, was studied in 30 motor units. All units but one generated peak tetanic tensions which were less than 0.22% of whole muscle tension. A high proportion (75%) of units demonstrated fatigue resistance, reflective of the demands of sustained flapping flight. These preliminary data suggest that the peripheral neuromuscular systems of Clione and Columba share some common components for the execution of at least two distinct modes of flapping locomotion.