Tardigrades exhibit robust interlimb coordination across walking speeds and terrains. Author Jasmine Nirody, Lisset Duran, Deborah Johnston, Daniel Cohen Publication Year 2021 Type Journal Article Abstract Tardigrades must negotiate heterogeneous, fluctuating environments and accordingly utilize locomotive strategies capable of dealing with variable terrain. We analyze the kinematics and interleg coordination of freely walking tardigrades (species: ). We find that tardigrade walking replicates several key features of walking in insects despite disparities in size, skeleton, and habitat. To test the effect of environmental changes on tardigrade locomotor control circuits we measure kinematics and interleg coordination during walking on two substrates of different stiffnesses. We find that the phase offset between contralateral leg pairs is flexible, while ipsilateral coordination is preserved across environmental conditions. This mirrors similar results in insects and crustaceans. We propose that these functional similarities in walking coordination between tardigrades and arthropods is either due to a generalized locomotor control circuit common to panarthropods or to independent convergence onto an optimal strategy for robust multilegged control in small animals with simple circuitry. Our results highlight the value of tardigrades as a comparative system toward understanding the mechanisms-neural and/or mechanical-underlying coordination in panarthropod locomotion. Keywords Animals, Biomechanical Phenomena, Locomotion, Biological Evolution, Video Recording, Image Processing, Computer-Assisted, Lower Extremity, Tardigrada, Walking, Walking Speed Journal Proc Natl Acad Sci U S A Volume 118 Issue 35 Date Published 2021 Aug 31 ISSN Number 1091-6490 DOI 10.1073/pnas.2107289118 Alternate Journal Proc Natl Acad Sci U S A PMCID PMC8536314 PMID 34446560 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML