Sheppard-Brennand Hannah, Poore Alistair G B, Dworjanyn Symon A
Am Nat. 2017 Jun;189(6):700-708. doi: 10.1086/691437. Epub 2017 Mar 27.
Selection by consumers has led to the evolution of a vast array of defenses in animals and plants. These defenses include physical structures, behaviors, and chemical signals that mediate interactions with predators. Some of the strangest defensive structures in nature are the globiferous pedicellariae of the echinoderms. These are small venomous appendages with jaws and teeth that cover the test of many sea urchins and sea stars. In this study, we report a unique use of these defensive structures by the collector sea urchin Tripneustes gratilla. In both the laboratory and the field, globiferous pedicellariae were unpalatable to fish consumers. When subject to simulated predator attack, sea urchins released a cloud of pedicellaria heads into the water column. Flume experiments established the presence of a waterborne cue associated with this release of pedicellariae that is deterrent to predatory fish. These novel results add to our understanding of how the ecosystem-shaping sea urchin T. gratilla is able to reach high densities in many reef habitats, with subsequent impacts on algal cover.
消费者的选择导致动植物进化出了大量防御机制。这些防御机制包括物理结构、行为以及介导与捕食者相互作用的化学信号。自然界中一些最奇特的防御结构是棘皮动物的叉棘。这些是带有颚和牙齿的小型有毒附属物，覆盖在许多海胆和海星的外壳上。在本研究中，我们报告了收集者海胆（T. gratilla）对这些防御结构的一种独特利用方式。在实验室和野外环境中，叉棘对鱼类消费者来说都不可口。当受到模拟捕食者攻击时，海胆会向水柱中释放一团叉棘头部。水槽实验证实，与叉棘释放相关的一种水溶性信号对掠食性鱼类具有威慑作用。这些新结果增进了我们对塑造生态系统的海胆T. gratilla如何能够在许多珊瑚礁栖息地达到高密度以及随后对藻类覆盖产生影响的理解。
