Department of Integrative Biology, University of California, 1005 Valley Life Sciences Building no. 3140, Berkeley, CA 94720-3140, USA.
J R Soc Interface. 2012 Dec 7;9(77):3574-7. doi: 10.1098/rsif.2012.0501. Epub 2012 Aug 15.
Architectural creations occur throughout the animal kingdom, with invertebrates and vertebrates building structures such as homes to maximize their Darwinian fitness. Animal architects face many trade-offs in building optimally designed structures. But what about animals that do not build, and those that only remodel the original creations of others: do such secondary architects face similar trade-offs? Recent evidence has revealed that hermit crabs-animals well known for opportunistically moving into remnant gastropod shells-can also act as secondary architects, remodelling the shells they inherit from gastropods. Remodelling has only been found among terrestrial hermits (Coenobita spp.), not marine hermits. Here we investigate the potential trade-offs Coenobita compressus faces from remodelling by subjecting its remodelled and unremodelled homes to controlled engineering crush tests, which parallel the homes being crushed by predators. While remodelled homes are significantly more spacious and lightweight than unremodelled homes, we find that the homes attain these beneficial qualities at a cost: a reduced resistance to being crushed. Hermit crabs may therefore only remodel their homes to thresholds set by the bite force of their predators. Our results suggest that, like primary animal architects, which face trade-offs when optimizing architectural designs, secondary animal architects face trade-offs when remodelling such designs.
动物王国中存在着各种建筑创作，无脊椎动物和脊椎动物都会建造住所等结构，以最大限度地提高其达尔文适应度。动物建筑师在建造最佳设计结构时会面临许多权衡。但是，那些不建造结构的动物，以及那些只改造他人原始创作的动物呢：这些次要建筑师是否面临类似的权衡？最近的证据表明，寄居蟹——以机会主义地搬进剩余腹足纲贝壳而闻名的动物——也可以充当次要建筑师，改造它们从腹足纲动物那里继承来的贝壳。这种改造仅在陆生寄居蟹（Coenobita spp.）中发现，而不在海洋寄居蟹中发现。在这里，我们通过对其改造和未改造的住所进行受控工程压碎测试来研究 Coenobita compressus 面临的潜在权衡，这些测试与被捕食者压碎住所的情况类似。虽然改造后的住所明显比未改造的住所宽敞和轻便，但我们发现这些住所具有这些有益的特性是有代价的：抗碎能力降低。因此，寄居蟹可能只会将其住所改造到其捕食者的咬合力设定的阈值。我们的研究结果表明，与优化建筑设计时面临权衡的主要动物建筑师一样，改造这些设计的次要动物建筑师也面临权衡。
