Intramuscular crossed connective tissue fibres: skeletal support in the lateral fins of squid and cuttlefish (Mollusca: Cephalopoda)

Published

Journal Article

The lateral fins of cuttlefish and squid were modelled to test the hypothesis that an array of crossed connective tissue fibres embedded within the musculature of the fins provides the support required for bending and to evaluate the role of the connective tissue in elastic energy storage. Previous morphological studies showed that the fins consist of a tightly packed array of musculature similar to that found in other muscular hydrostats. However, an electromyographical study of low amplitude, low frequency fin beating found that, unlike other muscular hydrostats, synergistic muscle contractions do not provide the support required for fin bending. Three computer simulations were performed. The first, a force analysis. considered the resistance to lateral compression provided by the crossed connective tissue fibres of an unbent fin. The second, an energy minimization analysis, considered the shape and deformation of the fin when subjected to lateral compressive forces confined to either the dorsal or ventral surface of the fin. The results from these first two simulations were combined in a third simulation that calculated the upper limit for connective tissue strain as a function of the angle subtended by the arc of the fin. This last simulation suggests that the connective tissue array provides the support required. It also predicts that the connective tissue strain is slightly nonā€linear as a function of fin angle and that the connective tissue fibres on the concave side are considerably more strained than those on the convex side of a bent fin. Further, the original fibre angle of the connective tissue is such that the total amount of elastic energy stored in the array is parabolic as a function of fin angle, suggesting that the array may allow the fin to function as a harmonic oscillator. The ‘spring stiffness’ predicted by the model approximates the optimal value calculated for a harmonically oscillating fin at the frequency and wavelength observed. This suggests that elastic energy storage in the connective tissue fibre array may increase the efficiency of the fins during locomotion. Copyright © 1993, Wiley Blackwell. All rights reserved

Full Text

Duke Authors

Cited Authors

  • Johnsen, S; Kier, WM

Published Date

  • January 1, 1993

Published In

Volume / Issue

  • 231 / 2

Start / End Page

  • 311 - 338

Electronic International Standard Serial Number (EISSN)

  • 1469-7998

International Standard Serial Number (ISSN)

  • 0952-8369

Digital Object Identifier (DOI)

  • 10.1111/j.1469-7998.1993.tb01921.x

Citation Source

  • Scopus