Walls Michael L, Layne John E
Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
J Exp Biol. 2009 Oct;212(Pt 20):3236-40. doi: 10.1242/jeb.031831.
Foraging fiddler crabs (Uca spp.) monitor the location of, and are able to return to, their burrows by employing path integration. This requires them to accurately measure both the directions and distances of their locomotory movements. Even though most fiddler crabs inhabit relatively flat terrain, they must cope with vertical features of their environment, such as sloping beaches, mounds and shells, which may represent significant obstacles. To determine whether fiddler crabs can successfully perform path integration among such three-dimensional obstacles, we tested their ability to measure distance while we imposed a vertical detour. By inserting a large hill in the homeward path of foraging crabs we show that fiddler crabs can cope with vertical detours: they accurately travel the correct horizontal distance, despite the fact that the shape of the hill forces them to change their gait from what would be used on flat ground. Our results demonstrate a flexible path integrator capable of measuring, and either integrating or discarding, the vertical dimension.
觅食的招潮蟹（Uca属）通过路径积分来监测其洞穴的位置，并能够返回洞穴。这要求它们准确测量自身运动的方向和距离。尽管大多数招潮蟹栖息在相对平坦的地形中，但它们必须应对环境中的垂直特征，如倾斜的海滩、土堆和贝壳，这些可能是重大障碍。为了确定招潮蟹是否能在这些三维障碍物之间成功进行路径积分，我们在设置垂直迂回路线的情况下测试了它们测量距离的能力。通过在觅食螃蟹的归途中插入一座大山，我们发现招潮蟹能够应对垂直迂回：它们能准确地行进正确的水平距离，尽管山的形状迫使它们改变在平地上的步态。我们的结果表明，招潮蟹拥有一个灵活的路径积分系统，能够测量垂直维度，并对其进行积分或忽略。
