The structural origins of brittle star arm kinematics: An integrated tomographic, additive manufacturing, and parametric modeling-based approach

February 20, 2020

Lara Tomholt (1,2), Larry J. Friesen (3), Daniel Berdichevsky (1,2), Matheus C. Fernandes (1,4), Christoph Pierre (5), Robert J. Wood (1,4), James C. Weaver (1)
Journal of Structural Biology, February 2020. DOI: 10.1016/j.jsb.2020.107481


Brittle star, Ophiuroidea, biomineralization, biomechanics, parametric modeling, 3D printing, finite element


Brittle stars are known for the high flexibility of their arms, a characteristic required for locomotion, food grasping, and for holding onto a great diversity of substrates. Their high agility is facilitated by the numerous discrete skeletal elements (ossicles) running through the center of each arm and embedded in the skin. While much has been learned regarding the structural diversity of these ossicles, which are important characters for taxonomic purposes, their impact on the arms’ range of motion, by contrast, is poorly understood. In the present study, we set out to investigate how ossicle morphology and skeletal organization affect the flexibility of brittle star arms. Here, we present the results of an in-depth analysis of three brittle star species (Ophioplocus esmarki, Ophiopteris papillosa, and Ophiothrix spiculata), chosen for their different ranges of motion, as well as spine size and orientation. Using an integrated approach that combines behavioral studies with parametric modeling, additive manufacturing, micro-computed tomography, scanning electron microscopy, and finite element simulations, we present a high-throughput workflow that provides a fundamental understanding of 3D structure-kinematic relationships in brittle star skeletal systems.

How Our Software Was Used

Dragonfly was used to perform image segmentation, visualization, and analysis.

Author Affiliation

(1) Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, Boston, MA 02115,USA.
(2) Harvard University Graduate School of Design, 48 Quincy St, Cambridge, MA 02138, USA.
(3) Department of Biological Sciences, Santa Barbara City College, Santa Barbara, CA 93109, USA.
(4) John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 USA.
(5) UCSB Marine Operations, University of California, Santa Barbara, CA 93106, USA.