Department of Ecology, Evolution and Organismal Biology, Brown University, Providence, RI 02912, USA.
School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Proc Biol Sci. 2023 Apr 12;290(1996):20230520. doi: 10.1098/rspb.2023.0520.
Throughout evolution, organisms repeatedly developed elastic elements to power explosive body motions, overcoming ubiquitous limits on the power capacity of fast-contracting muscles. Seahorses evolved such a latch-mediated spring-actuated (LaMSA) mechanism; however, it is unclear how this mechanism powers the two complementary functions necessary for feeding: rapidly swinging the head towards the prey, and sucking water into the mouth to entrain it. Here, we combine flow visualization and hydrodynamic modelling to estimate the net power required for accelerating the suction feeding flows in 13 fish species. We show that the mass-specific power of suction feeding in seahorses is approximately three times higher than the maximum recorded from any vertebrate muscle, resulting in suction flows that are approximately eight times faster than similar-sized fishes. Using material testing, we reveal that the rapid contraction of the sternohyoideus tendons can release approximately 72% of the power needed to accelerate the water into the mouth. We conclude that the LaMSA system in seahorses is powered by two elastic elements, the sternohyoideus and epaxial tendons. These elements jointly actuate the coordinated acceleration of the head and the fluid in front of the mouth. These findings extend the known function, capacity and design of LaMSA systems.
在进化过程中，生物体反复开发弹性元件以产生爆发性的身体运动，克服了快速收缩肌肉在功率容量上的普遍限制。海马进化出了一种由闩锁介导的弹簧驱动（LaMSA）机制；然而，目前尚不清楚这种机制如何为进食所需的两个互补功能提供动力：快速将头部转向猎物，以及将水吸入嘴中以带动猎物。在这里，我们结合流动可视化和水动力模型来估计 13 种鱼类加速吸吮式进食流所需的净功率。我们表明，海马的单位质量吸吮式进食功率大约是任何脊椎动物肌肉记录的最大值的三倍，导致的吸吮流速度大约是类似大小鱼类的八倍。通过材料测试，我们揭示了胸舌骨肌肌腱的快速收缩可以释放大约 72%加速水进入嘴中所需的功率。我们的结论是，海马中的 LaMSA 系统由两个弹性元件，即胸舌骨肌和背侧肌腱驱动。这些元件共同作用，协调头部和嘴前面的流体的加速。这些发现扩展了已知的 LaMSA 系统的功能、容量和设计。
