A non-destructive test was developed to measure the static mechanical properties of the locomotor structure (bell) in the hydromedusan jellyfish, Polyorchis penicillatus (Eschscholtz, 1829). A nonlinear stress-strain relationship was found, and the mean static structural stiffness of the bell was 150 N m−2. Visualization procedures that showed the natural changes in the geometry of the deformation of the bell were used to calculate the static modulus of elasticity of the mesoglea, and gave a modulus of 400 N m−2. Dynamic measurements on isolated samples of mesoglea gave a mean storage modulus of 1000 N m−2. The resilience of the material was about 58%. These data were integrated to imply that the dynamic structural stiffness of the bell is at least 400 N m−2. Attempts to measure the dynamic structural stiffness directly indicate that the dynamic stiffness of the intact bell lies between 400 and 1000 N m−2. All, or most, of the potential energy stored in the mesoglea during contractions of the bell is stored as strain energy in the radial mesogleal fibres.
Mechanics of Jet Propulsion in the Hydromedusan Jellyfish, Polyorchis Pexicillatus: I. Mechanical Properties of the Locomotor Structure
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M. EDWIN DEMONT, JOHN M. GOSLINE; Mechanics of Jet Propulsion in the Hydromedusan Jellyfish, Polyorchis Pexicillatus: I. Mechanical Properties of the Locomotor Structure. J Exp Biol 1 January 1988; 134 (1): 313–332. doi: https://doi.org/10.1242/jeb.134.1.313
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