鲸目动物(海豚,鲸鱼,和海豚)是完全水生的哺乳动物,它们受到水的浮力支撑,并通过轴向身体弯曲游泳。游泳部分地由椎骨形态的变化介导,其在轴向区域之间产生身体柔性和刚度的权衡,从而增强或减少相邻椎骨之间的位移。游泳行为与觅食生态有关,与浅层潜水的鲸类动物相比,深潜的鲸类动物滑行的时间比例更大。在这项研究中,我们将10种鲸类(Delphinidae和Kogiidae)分为由游泳模式决定的功能组(刚性与灵活的躯干)和潜水行为(浅与深)。这里,我们量化了功能组(刚体浅潜水员(RS),刚性躯干深潜水员(RD),和灵活躯干深度潜水员(FD)),和(B)在脊柱区域(胸椎后部,腰椎,尾花梗,和侥幸插入)。我们显微CT扫描椎体,从中选择1-5个感兴趣的体积来量化骨体积分数(BV/TV),特定骨表面(BS/BV),小梁厚度(TbTh),骨小梁数(TbN),小梁分离(TbSp),和各向异性程度(DA)。我们发现,在刚性躯干浅潜水功能组中,BV/TV最大,在灵活躯干深潜物种中最小的,在刚性躯干深潜组的中间。刚性躯干尾振荡器的DA明显大于柔性躯干振荡器的DA。对于任何微结构变量,我们发现椎骨区域之间没有变化。尽管有骨质疏松的骨骼,鲸类动物椎骨有更大的BV/TV,TbTh,和DA比以前在陆地哺乳动物骨骼中记录的要多。鲸类物种是研究长期适应的理想模型,在动物的一生和进化过程中,在非承重条件下小梁骨。
Cetaceans (dolphins, whales, and porpoises) are fully aquatic mammals that are supported by water\'s buoyancy and swim through axial body bending. Swimming is partially mediated by variations in vertebral morphology that creates trade-offs in body flexibility and rigidity between axial regions that either enhance or reduce displacement between adjacent vertebrae. Swimming behavior is linked to foraging ecology, where deep-diving cetaceans glide a greater proportion of the time compared to their shallow-diving counterparts. In this study, we categorized 10 species of cetaceans (Families Delphinidae and Kogiidae) into functional groups determined by swimming patterns (rigid vs. flexible torso) and diving behavior (shallow vs. deep). Here, we quantify vertebral trabecular microarchitecture (a) among functional groups (rigid-torso shallow diver (RS), rigid-torso deep diver (RD), and flexible-torso deep diver (FD)), and (b) among vertebral column regions (posterior thoracic, lumbar, caudal peduncle, and fluke insertion). We microCT scanned vertebral bodies, from which 1-5 volumes of interest were selected to quantify bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (TbTh), trabecular number (TbN), trabecular separation (TbSp), and degree of anisotropy (DA). We found that BV/TV was greatest in the rigid-torso shallow-diving functional group, smallest in flexible-torso deep-diving species, and intermediate in the rigid-torso deep-diving group. DA was significantly greater in rigid-torso caudal oscillators than in their flexible-torso counterparts. We found no variation among vertebral regions for any microarchitectural variables. Despite having osteoporotic skeletons, cetacean vertebrae had greater BV/TV, TbTh, and DA than previously documented in terrestrial mammalian bone. Cetacean species are an ideal model to investigate the long-term adaptations, over an animal\'s lifetime and over evolutionary time, of trabecular bone in non-weight-bearing conditions.