Elner R W
Department of Zoology, University College of North Wales, Bangor, Gwynedd, United Kingdom.
Oecologia. 1978 Jan;36(3):333-344. doi: 10.1007/BF00348059.
Mechanical aspects of predation by the shore crab, Carcinus maenas, on the edible mussel, Mytilus edulis, were examined. The shore crabs from the population studied utilized five distinct, largely size-related, mussel-opening techniques. Crushing the mussel umbone appeared the most successful opening method for medium-sized prey. Small mussels were crushed outright and large mussels could be opened by a slow, uneconomical, boring technique. The strengths of mussels, from an exposed shore, were tested under compression in four separate planes to determine the loads a crab would need to apply to crush the shells outright and the mechanical properties of mussels. Little inter-plane variability in compressive strength was observed, although intra-plane variability appeared high. The compressive strengths of mussels from a sheltered shore were found to be significantly higher than those from the exposed shore in the plane tested. A strain gauge was embedded in a mussel shell enabling the pattern and magnitude of forces produced by crab chelae in opening a mussel to be studied. The crab's chelae did not appear overwhelmingly strong when compared directly to the compressive strength of the crab's preferred mussel sizes. It is, therefore, postulated that crabs usually seek out and exploit weak spots in the umbone of mussels by trial and error, eventually breaking through the shell by a cumulative process of extending minute fractures in the shell substructure.
研究了滨蟹（Carcinus maenas）捕食食用贻贝（Mytilus edulis）的力学方面。所研究种群中的滨蟹运用了五种不同的、主要与大小相关的贻贝开口技术。对于中等大小的猎物，压碎贻贝的壳顶似乎是最成功的开口方法。小贻贝会被直接压碎，而大贻贝则可以通过一种缓慢、不经济的钻孔技术打开。对来自暴露海岸的贻贝在四个不同平面上进行压缩测试，以确定螃蟹直接压碎贝壳所需施加的负荷以及贻贝的力学性能。尽管平面内变异性似乎较高，但观察到平面间抗压强度的变异性较小。发现在测试平面上，来自庇护海岸的贻贝的抗压强度明显高于来自暴露海岸的贻贝。将一个应变片嵌入贻贝壳中，以便研究螃蟹螯足在打开贻贝时产生的力的模式和大小。与螃蟹偏好的贻贝大小的抗压强度直接比较时，螃蟹的螯足看起来并不是特别强壮。因此，推测螃蟹通常通过试错来寻找并利用贻贝壳顶的薄弱点，最终通过在贝壳亚结构中扩展微小裂缝的累积过程来突破贝壳。
