Biomimetics of Regular Sea Urchin Spines

The external and internal morphologies of cidaroid and camarodont sea urchin primary spines are investigated giving an overview of the internal microstructure and structural properties. The investigated species comprise the cidaroids Eucidaris metularia, Phyllacanthus imperialis, Plococidaris verticillata and Prionocidaris baculosa as well as the camarodont Heterocentrotus mammillatus (Echinodermata: Class Echinoidea), and morphological descriptions are based on scanning electron microscopy and micro-computed tomography. Stereom types and densities are differentiated using pore and trabecular diameter measurements. Structural analysis was performed using three point bending tests resulting in the calculation of force, deflection and stress, strain relationships. All studied species possess primary spines with a medulla consisting of laminar stereom regardless of the age and position of the spine on the tests. Differences in spine morphologies and reaction to stress are interpreted with respect to functional morphological response, to ambient environmental parameters and their strategies between and within evolutionary stages.

Echinoid stereom measurements (Grossmann & Nebelsick, 2015)

CT scan of Echinometra spines (Nebelsick et al. 2016)

Nebelsick, J.H., Dynowski, J.F., Grossmann, J.N. & Tötzke, C. (2015): Echinoderms: Hierarchically organized light weight skeletons. In: Hamm, C. (ed.): Evolution of Lightweight Structures: Analyses and Technical Applications, Biologically-Inspired Systems, Vol. 6, Springer Verlag. 141-156. DOI 10.1007/978-017-9398-8_8. ISBN-10: 9401793972.

Grossmann, J.N. & Nebelsick, J.H. (2013): Comparative morphological and structural analysis of selected cidaroid and camarodont sea urchin spines. Zoomorphology. 132 (3), 301-315. DOI: 10.1007/s00435-013-0192-5.

Grossmann, N. & Nebelsick, J.H. (2013): Stereom Differentiation in spines of Plococidaris verticillata, Heterocentrotus mammillatus and other regular sea urchins. In: Johnson, C. (ed.) Echinoderms in a changing World. Proceedings of the 13th International Echinoderm Conference, Tasmania, 97-104.