Patek and former lab undergraduate, Marco Mendoza Blanco, publish a new paper in the journal Evolution entitled, "Muscle tradeoffs in a power-amplified prey capture system". This study offers a new window into the classic force-velocity tradeoffs in muscle contractions placed in the context of the evolution of power-amplified systems.
Check out the preprint here.
Mendoza Blanco, M. and S. N. Patek. 2014 Muscle tradeoffs in a power-amplified prey capture system. Evolution (published online).
Should animals operating at great speeds and accelerations use fast or slow muscles?
The answer hinges on a fundamental tradeoff: muscles can be maximally fast or forceful, but
not both. Direct lever systems offer a straightforward manifestation of this tradeoff, yet the
fastest organisms use power amplification, not direct lever action. Power-amplified systems
typically use slow, forceful muscles to pre-load springs which then rapidly release elastic
potential energy to generate high speeds and accelerations. However, a fast response to a
stimulus may necessitate fast spring-loading. Across 22 mantis shrimp species
(Stomatopoda), this study examined how muscle anatomy correlates with spring mechanics
and appendage type. We found that muscle force is maximized through physiological crosssectional
area, but not through sarcomere length. Sit-and-wait predators had the shortest
sarcomere lengths (fastest contractions) and the slowest strike speeds. The species that crush
shells (“smashers”) had the fastest speeds, most forceful springs and longest sarcomeres. The
origin of the smasher clade yielded dazzlingly high accelerations, perhaps due to the release
from fast spring-loading for evasive prey capture. This study offers a new window into the
dynamics of force-speed tradeoffs in muscles in the biomechanical, comparative evolutionary
framework of power-amplified systems.