George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
School of Biological Sciences, George Washington University, Washington, DC 20052, USA.
Integr Comp Biol. 2022 Aug 13;62(1):81-89. doi: 10.1093/icb/icac006.
Body size affects nearly every aspect of locomotion and sensing, but little is known of its influence on olfaction. One reason for this missing link is that olfaction differs fundamentally from vision and hearing in that molecules are advected by fluid before depositing on olfactory sensors. This critical role of fluid flow in olfaction leads to complexities and trade-offs. For example, a greater density of hairs and sensory neurons may lead to greater collection, but can also lead to reduced flow through hairs and additional weight and drag due to a larger olfactory organ. In this study, we report the surface area and sensory neuron density in olfactory organs of 95 species of moths and mammals. We find that approximately 12-14% of an olfactory system's surface area is devoted to chemosensors. Furthermore, total olfactory surface area and olfactory sensing surface area scale with body mass to the 0.49 and 0.38 powers, respectively, indicating that moths have a higher proportion of olfactory surface area than mammals. The density of olfactory neurons appears to be near the limit, at 10,000 to 100,000 neurons per square mm across both insects and mammals. This study demonstrates the need for future work detailing how the scaling of olfaction and other senses vary across taxa.
体型几乎影响着运动和感知的方方面面，但关于体型对嗅觉的影响却知之甚少。造成这一缺失环节的原因之一是，嗅觉与视觉和听觉有根本的不同，因为分子在沉积到嗅觉传感器之前是被流体输送的。这种流体流动在嗅觉中的关键作用导致了复杂性和权衡。例如，更多的毛发和感觉神经元可能会导致更大的收集量，但也会导致毛发中的流动减少，以及由于更大的嗅觉器官而导致的额外重量和阻力。在这项研究中，我们报告了 95 种蛾类和哺乳动物嗅觉器官的表面积和感觉神经元密度。我们发现，嗅觉系统的表面积约有 12-14%用于化学感受器。此外，总嗅觉表面积和嗅觉感觉表面积与体重的 0.49 和 0.38 次幂成正比，这表明蛾类的嗅觉表面积比例高于哺乳动物。嗅觉神经元的密度似乎接近极限，在昆虫和哺乳动物中，每平方毫米有 1 万到 10 万个神经元。这项研究表明，需要进一步研究详细说明嗅觉和其他感觉的缩放如何在不同分类群中变化。
