The Contractile Properties and Biomechanics of the Obliquely-Striated Adductor Muscles of Ensis directus
Several studies have been conducted on muscle function in a variety of species in vivo. However, they are limited by technology and behavior because many animals range over areas far too broad to support the electrodes, transducers, and wire leads necessary to monitor muscle function. Atlantic razor clams (Ensis directus) are an ideal model species in which to investigate in vivo muscle performance because despite being relatively active burrowers, especially when compared to other clams, they typically range over distances of less than 1.0 m. Through microscopy, posterior adductor muscle fiber trajectory was determined to be perpendicular to the valves of the clam, thus paving the way for electromyography (EMG) data collection. High-speed videography of valve closure synchronized with electromyography (EMG) of the adductor muscles yielded timing, duration, and amplitude of EMG signals in addition to the frequency of valve closure. Evidence supports that the clams valves close in accordance with adductor muscle activation. Gape changes over time yielded a peak shortening velocity that, over the population, is comparable to those of other obliquely striated muscles. Frequency of valve closure was also calculated, leading to a better understanding of how quickly these clams can jet and burrow. These data laid the foundation for calculating work output and furthering research on tradeoffs in muscle biomechanics and energy expenditures in the field; future experiments performed on adductor muscles in razor clams will add an ecological dimension to studies of muscle physiology.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2016
- F&M Theses Collection