Sea star inspired crawling and bouncing

Abstract

<jats:p>The oral surface of sea stars is lined with arrays of tube feet that enable them to achieve highly controlled locomotion on various terrains. The activity of the tube feet is orchestrated by a nervous system that is distributed throughout the body without a central brain. How such a distributed nervous system produces a coordinated locomotion is yet to be understood. We develop mathematical models of the biomechanics of the tube feet and the sea star body. In the model, the feet are coupled mechanically through their structural connection to a rigid body. We formulate hierarchical control laws that capture salient features of the sea star nervous system. Namely, at the tube foot level, the power and recovery strokes follow a state-dependent feedback controller. At the system level, a directionality command is communicated through the nervous system to all tube feet. We study the locomotion gaits afforded by this hierarchical control model. We find that these minimally coupled tube feet coordinate to generate robust forward locomotion, reminiscent of the crawling motion of sea stars, on various terrains and for heterogeneous tube feet parameters and initial conditions. Our model also predicts a transition from crawling to bouncing consistently with recent experiments. We conclude by commenting on the implications of these findings for understanding the neuromechanics of sea stars and their potential application to autonomous robotic systems.</jats:p>

Field testing of biohybrid robotic jellyfish to demonstrate enhanced swimming speeds

“…Examples of bioinspired aquatic robots include robotic fish [16][17][18], manta rays [19][20][21], sea stars [22,23], and jellyfish [24][25][26][27][28][29], including systems that have been deployed in real-world environments [16,24].…”

Three-dimensional visualization as a tool for interpreting locomotion strategies in ophiuroids from the Devonian Hunsrück Slate

“…The ambulacrals in these ophiuroids tend to be separated proximodistally and, in some cases, tightly juxtaposed across the midline of the arm (in our specimens of E. roemeri, L. mirabilis). The closest living relatives of ophiuroids (Asteroidea, Echinoidea) use podial walking for locomotion [2][3][4] and the musculoskeletally-driven locomotion strategy of extant ophiuroids is derived. This suggests that the unique locomotion strategy used by modern ophiuroids evolved after their most recent common ancestor with other modern taxa.…”

“…The integrated body structure of an organism and the morphology of its components determine the locomotion strategies available to it [ 1 ]. The majority of living ophiuroids employ a unique strategy involving the coordination of whip-like motions of their five muscular arms, in contrast to their closest living relatives including the sea stars and sea urchins [ 2 – 4 ], which primarily use tube feet and move more slowly. Reconstructing the evolutionary history of ophiuroid locomotion is challenging as the morphology of the arms of many fossil ophiuroids differs from that in living forms, from the basic structure and number of elements to their arrangement and integration.…”

“…Living ophiuroids generally coordinate periodic musculoskeletally-driven oscillations of their arms to effect rapid locomotion [ 26 – 28 ]. Related taxa such as sea stars and sea urchins [ 3 , 4 , 14 , 29 ], by contrast, use tube feet as a primary tool for locomotion. This suggests that musculoskeletally-driven locomotion in living ophiuroids is derived from a tube foot-walking ancestor.…”

Field Testing of Biohybrid Robotic Jellyfish to Demonstrate Enhanced Swimming Speeds

“…Bioinspired soft robots can potentially address issues in power consumption [ 13 , 15 ] and leave wakes that mimic the wakes of marine life, with potential to minimally perturb surrounding wildlife. Examples of bioinspired aquatic robots include robotic fish [ 16 , 17 , 18 ], manta rays [ 19 , 20 , 21 ], sea stars [ 22 , 23 ], and jellyfish [ 24 , 25 , 26 , 27 , 28 , 29 ], including systems that have been deployed in real-world environments [ 16 , 24 ].…”