Collaborative Research: The Function and Evolution of the Hammerhead Shark Cephalofoil

锤头鲨是在形态和功能上进化分化的最显著的例子之一。翼鲨的头部或头箔极大地展开，其体长可能只有翼鲨的一半大，也可能只是稍大一些，而在白头鲨则只有轻微的增大。侧向扩张的头部的功能尚不清楚，但假设包括更大的机动性和升降力，更好的嗅觉分辨率，增强的双眼和侧视，以及更好的电或机械接收。本项目利用各种不同头部形状的物种(E.blchii、大锤头S.mokarran、光滑锤头S.zygaena、扇形锤头S.lewini、扇形锤头S.corona、勺头S.media和S.tiburo)研究锤头鲨头翼的功能和进化。本研究将：利用现代分子DNA分析建立锤头鲨的进化史；分析锤头鲨在感觉、摄食和呼吸结构上的功能和解剖学差异；比较扩展的头箔与更接近的黑鼻鲨和更典型的尖头黑鼻鲨的感官能力；研究扩展的头部在运动和机动性中的作用；最后，揭示导致这种惊人头部形态的结构和功能变化的进化序列。这些目标将通过整合进化生物学家、感官生理学家、功能形态学家和流体工程师的专业知识以及利用佛罗里达州莫特海洋实验室的专门鲨鱼研究设施来实现。这项合作研究将确定导致这种奇怪头部形式进化的选择压力，并增加我们对鲨鱼的结构、功能和进化的了解，鲨鱼是一种过度捕捞和耗尽的海洋捕食者群体。该项目促进了各级教育的培训、教学和学习。本科生和研究生将在进化生物学、感觉生理学、解剖学和生物力学方面进行交叉培训。这项研究将整合到三所大学的研究生和本科生层面的教学中。由于公众对鲨鱼的广泛兴趣，私人投资者将通过报纸和杂志社论、电视纪录片和博物馆展览，为成年人提供学童的公共宣传和教育。

The hammerhead sharks offer one of the most striking examples of evolutionary divergence in form and function. The greatly expanded head or cephalofoil may be as great as half their body length in the winghead shark Eusphyra blochii or only slightly enlarged as in the bonnethead shark Sphyrna tiburo. The function of the laterally expanded head is unclear, but hypotheses include greater maneuverability and lift, better olfactory resolution, enhanced binocular and lateral vision, and superior electro- or mechanoreception. This project investigates the function and evolution of the hammerhead shark cephalofoil utilizing a variety of species with divergent head shapes (E. blochii, the great hammerhead S. mokarran, smooth hammerhead S. zygaena, the scalloped hammerhead S. lewini, scalloped bonnethead S. corona, scoophead S. media, and S. tiburo). This study will: establish an evolutionary history of the hammerhead sharks using modern molecular DNA analysis; examine the functional and anatomical differences in the sensory, feeding and respiratory structures among the hammerhead sharks; compare the sensory capabilities of the expanded cephalofoil to the closely related blacknose shark, Carcharhinus acronotus with its more typical pointed head; investigate the role of the expanded head in locomotion and maneuverability; and finally, reveal the evolutionary sequence of structural and functional changes that have resulted in this striking head form. These goals will be accomplished by integrating the expertise of evolutionary biologists, sensory physiologists, functional morphologists, and fluid engineers along with utilizing the specialized shark research facilities of Mote Marine Laboratory in Florida. This collaborative study will identify the selective pressures that have resulted in the evolution of this bizarre head form, and increase our knowledge of the structure, function, and evolution of sharks, an overfished and depleted group of marine predators. This project promotes training, teaching, and learning at all educational levels. Undergraduate and graduate students will be cross-trained in evolutionary biology, sensory physiology, anatomy and biomechanics. This research will be integrated into teaching at the graduate and undergraduate levels at three universities. Because of the broad public interest in sharks the PIs will provide public outreach and education for school children to adults through newspaper and magazine editorials, television documentaries, and museum displays.