Pates Stephen, Ma Jiaxin, Wu Yu, Fu Dongjing
Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK.
Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK.
R Soc Open Sci. 2024 Dec 11;11(12):240894. doi: 10.1098/rsos.240894. eCollection 2024 Dec.
A metazoan-dominated biological pump was established early in the Phanerozoic, a time that saw the evolution of the first pelagic euarthropod zooplankton such as some species of the Cambrian bivalved euarthropod . Pelagic groups evolved from benthic stock, in many cases through neoteny and retention of characteristics from planktic larval stages. However, brooded eggs and did not have a planktic larval stage, precluding this route into the pelagic realm. Computational fluid dynamics was used to quantify hydrodynamic performance through the ontogeny of two hyperbenthic species of and . Coefficients were used to quantify forces for different carapace shapes over a range of biologically relevant sizes and swimming speeds. Streamlining and lift generation were greater for later growth stages, a consequence of carapace asymmetry and elongated anterior and posterior spines. Simulations performed with anterior spines artificially removed demonstrate the importance of this feature for lift generation, with a minimal impact on drag. Elongated spines and faster swimming can also be considered anti-predatory, and the reduction of drag would have reduced the detectability of to predators. Taken together, it is likely that pelagic species evolved from benthic stock through the co-option of anti-predatory features.
后生动物主导的生物泵在显生宙早期就已建立，这一时期见证了第一批远洋真节肢动物浮游动物的进化，比如寒武纪双瓣真节肢动物的某些物种。远洋类群从底栖类群演化而来，在许多情况下是通过幼态持续以及保留浮游幼虫阶段的特征。然而，[具体物种]是卵胎生，没有浮游幼虫阶段，排除了这条进入远洋领域的途径。计算流体动力学被用于量化两种超底栖[具体物种]个体发育过程中的流体动力学性能。系数被用来量化在一系列生物学相关尺寸和游泳速度下不同甲壳形状所受的力。对于后期生长阶段，流线型和升力产生更为显著，这是甲壳不对称以及前后棘延长的结果。对人工移除前棘的模拟表明了这一特征对升力产生的重要性，而对阻力的影响最小。延长的棘和更快的游泳速度也可被视为反捕食特征，并且阻力的降低会减少[具体物种]被捕食者发现的可能性。综合来看，远洋[具体物种]很可能是通过利用反捕食特征从底栖类群演化而来。
