Walking Behavior Observed inPhoxichilidium femoratum(Rathke, 1799) andNymphon brevirostreHodge 1863 Collected from Kandalaksha Bay of the White Sea, Russia

In this study, the walking behavior ofPhoxichilidium femoratumandNymphon brevirostrewas investigated using video recordings. The walking behavior ofP. femoratumwhile walking over the colonial hydroids that they normally feed on and on relatively smooth glass surfaces was observed. In the case ofN. brevirostre, only walking on smooth glass was observed. The movement of the legs while waking does not display a metachronal pattern like that observed in the true spiders. As the animals move, the walking legs on the leading side of the animal are used to pull the animal forward while those on the trailing side make little or no contribution to the motion of the animal. The promoter/remoter motions of the coxa 1-coxa 2 joint of the walking legs are involved in azimuthal changes in the body’s orientation, but not in paraxial locomotion. The extension of the tarsus and propodus segments appears to occur as a result of hydrodynamic drag when the legs are being flexed and/or pressed against a solid substrate.