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From bouncy legs to poisoned arrows: elastic movements in invertebrates
S. N. Patek, D. M. Dudek, M. V. Rosario


Elastic mechanisms in the invertebrates are fantastically diverse, yet much of this diversity can be captured by examining just a few fundamental physical principles. Our goals for this commentary are threefold. First, we aim to synthesize and simplify the fundamental principles underlying elastic mechanisms and show how different configurations of basic building blocks can be used for different functions. Second, we compare single rapid movements and rhythmic movements across six invertebrate examples – ranging from poisonous cnidarians to high-jumping froghoppers – and identify remarkable functional properties arising from their underlying elastic systems. Finally, we look to the future of this field and find two prime areas for exciting new discoveries – the evolutionary dynamics of elastic mechanisms and biomimicry of invertebrate elastic materials and mechanics.


  • Funding was provided by a National Science Foundation Integrative Organismal Systems grant (#1014573 to S.N.P.) and a Northeast Alliance for Graduate Education and the Professoriate (NEAGEP) internship to M.V.R.

  • Glossary

    Rubber-like protein found in molluscs.
    Arthropod tendon.
    The ratio between mechanical power output and metabolic power input. Typically, but not always, the efficiency of an activity increases as the material or structure being used becomes more resilient.
    Elastic modulus (Young's modulus of elasticity)
    The resistance of a material or structure to deformation as determined from the slope of a stress versus strain plot (SI units: N m–2).
    Elastic potential energy
    Potential energy stored by a spring.
    The point at which a structure breaks or a system can no longer perform.
    Mechanical advantage
    The factor by which either force or speed is amplified by a mechanism.
    The rate at which work is performed [work (N m) divided by time (s); SI units: W].
    Power amplification
    A system that decreases the time to perform work thereby increasing the power output.
    The percentage of absorbed elastic energy that is recovered upon unloading.
    Rubber-like protein found in arthropods.
    The spring found adjacent to the hinge in scallops that opens the valves.
    The resistance of a material or structure to deformation. It is typically determined from the slope of a force versus extension plot (SI units: N m–1).
    The amount of deformation of a structure relative to its resting length.
    The force applied to a material normalized by the cross-sectional area (SI units: N m–2).
    The distance over which a force is exerted (SI units: J).
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