Active background choice facilitates crypsis in a tropical crab

Animals can evade predators in multiple ways, one of the most effective of which is to avoid detection in the first place. We know much about the evolution of color patterns that match the visual background to avoid detection (i.e., crypsis), yet we know surprisingly less about the specific behaviors that have co-evolved with these morphological traits to enhance or maintain crypsis. We here explore whether the match between body color and background in a seemingly well-camouflaged tropical shore crab is a result of active background choice. Taking advantage of a coastal area in the Solomon Islands with variable sand color and a population of the pallid ghost crab Ocypode pallidula with varying carapace color, we experimentally tested whether individuals actively choose specific substrate that best matches their color patterns. We found that individuals taken from extreme sand colors chose substrate that maintained crypsis, with relatively darker crabs typically choosing dark sand and l...

动物规避捕食者的策略多种多样，其中最有效的手段之一便是从源头避免被天敌侦测。我们对匹配视觉背景以规避侦测的体色模式演化（即保护色（crypsis））已有较为充分的研究，但对与这些形态特征协同演化、用以强化或维持保护色的具体行为，认知却相对匮乏。本研究旨在探究：在一种伪装效果看似优异的热带滨蟹中，其体色与背景的匹配度是否源于主动选择栖息背景的行为。我们借助所罗门群岛一处沙色各异的沿海区域，以及一批背甲颜色存在差异的苍白鬼蟹（Ocypode pallidula）种群，通过实验验证这些个体是否会主动选择与自身体色模式最匹配的栖息底质。研究结果显示，从极端沙色环境中采集的个体均选择了能维持保护色的底质：体色相对更深的蟹类通常会选择深色沙底，而……