Figure 3: Arrangement of Sxa within the sponge motivates a structural mechanics model.
(a) A cross-section of the sponge reveals radial bundles of Sxa. (b) A bundle is composed of Sxa (dark) separated by spongin (light). (c) The presence of neighbors limits the deformation of a Sxa to a region of confinement (RoC). (d) Tractions applied to the ends of the RoC are transferred to the Sxa by the inter-spicule spongin (IS). (e) Von Mises stress computed from a computational mechanics model of (d). The distribution of axial force per unit length, Tz, along the length of a Sxa is localized at the ends. (f) A Sxa within its RoC, subjected to opposing forces with magnitude PM applied at its ends. A Sxa rotates until it is restrained by the presence of neighboring Sxa. The net force acting along a Sxa’s axis has a magnitude P, which includes contributions from PM and PN. The Sxa and RoC in (d)–(f) are not to scale. (g) A schematic of a simply supported column.
