Biomechanical Multifunctionality in the Ghost Crab, Ocypode quadrata

Bioinspired robotics has experienced unprecedented advancements. Robots can now run, swim and fly. Despite these advancements, the animals that inspired these robots remain substantially more versatile, using the same set of multifunctional appendages to perform many different tasks or behaviors. Understanding how biomechanics and behavior contribute to these capabilities will offer new insight into the science of animal movement and potentially inspire new multifunctional robotic technologies. Here, the ghost crab, Ocypode quadrata, was examined. These crabs, which are among the fastest land invertebrates, use relatively simple, unspecialized appendages to run, climb, burrow and dexterously capture prey. This dissertation focuses on ghost crabs’ burrowing and climbing behaviors. Both of these involve complex behavioral suites that involve the walking legs, the chelae and the body. Crabs demonstrated specialized postures, locomotion in confined spaces and goal-directed manipulation of both the environment and themselves. Both burrowing and climbing strategies involved compensatory strategies that allowed the crabs to maintain performance across a wide range of environmental conditions. Crabs do not rely on specialized appendage features but rather on the ability to use all appendages together. The findings presented in this dissertation represent new insight into the biomechanics of multifunctionality and offer inspiration for new bio-inspired robots with multi-use parts that permit, not simply obstacle negotiation, but also modification of the environment