In the first exploration of muscle dynamics in live lamnid sharks (a group that includes the great white and mako), the researchers found that in fact tunas and lamnids share a surprisingly close array of swimming muscle dynamics.
Scientists who study large fish in the open ocean have long noted the similarities in species that exhibit high-performance swimming mechanics, particularly those built for fast and continuous motion. For example, such swimming is exhibited in lamnid sharks, which have long been suspected of sharing a basic locomotor design with tunas.
"Tunas and lamnid sharks have a body form that represents an extreme in biomechanical design for high-performance swimming," said Scripps's Jeanine Donley, the first author of the study appearing in the May 6 issue of the scientific journal Nature. In fact, the research study, she says, reveals an "unprecedented level" of similarity between the two, including the dynamics of steady swimming and functional design of their complex locomotor systems.
The researchers set out to investigate the evolutionary crossroads between lamnid sharks and tunas in regards to the mechanics and architecture of their muscle-tendon systems. Recent research has uncovered a muscle design in tunas that separate them from their related "bony" fishes (see http://scrippsnews.ucsd.edu/pressreleases/shadwick_tuna1.cfm). But similar investigations probing the biomechanical designs of lamnid sharks had not been success
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University of California - San Diego