Davenport John, Fraher John, Fitzgerald Edward, McLaughlin Patrick, Doyle Tom, Harman Luke, Cuffe Tracy
Department of Zoology, Ecology and Plant Science and Environmental Research Institute, University College Cork, Distillery Fields, North Mall, Cork, Ireland.
J Exp Biol. 2009 Sep 1;212(17):2753-9. doi: 10.1242/jeb.026500.
Adult leatherback turtles are gigantothermic/endothermic when foraging in cool temperate waters, maintaining a core body temperature within the main body cavity of ca. 25 degrees C despite encountering surface temperatures of ca. 15 degrees C and temperatures as low as 0.4 degrees C during dives. Leatherbacks also eat very large quantities of cold, gelatinous prey (medusae and pyrosomas). We hypothesised that the head and neck of the leatherback would have structural features to minimise cephalic heat loss and limit cooling of the head and neck during food ingestion. By gross dissection and analytical computed tomography (validated by ground truthing dissection) of an embalmed specimen we confirmed this prediction. 21% of the head and neck was occupied by adipose tissue. This occurred as intracranial blubber, encapsulating the salt glands, medial portions of the eyeballs, plus the neurocranium and brain. The dorsal and lateral surfaces of the neck featured thick blubber pads whereas the carotid arteries and jugular veins were deeply buried in the neck and protected laterally by blubber. The oesophagus was surrounded by a thick sheath of adipose tissue whereas the oropharyngeal cavity had an adipose layer between it and the bony proportion of the palate, providing further ventral insulation for salt glands and neurocranium.
成年棱皮龟在凉爽的温带水域觅食时是巨温性/温血动物，尽管在潜水时遇到的表面温度约为15摄氏度，甚至低至0.4摄氏度，但它们能将体腔核心体温维持在约25摄氏度。棱皮龟还会大量食用冰冷的凝胶状猎物（水母和火体虫）。我们推测，棱皮龟的头部和颈部会有结构特征，以尽量减少头部热量损失，并在进食时限制头部和颈部的冷却。通过对一具防腐标本进行大体解剖和分析计算机断层扫描（经实地解剖验证），我们证实了这一预测。头部和颈部的21%被脂肪组织占据。这些脂肪组织以颅内脂肪的形式存在，包裹着盐腺、眼球内侧部分，以及脑颅和大脑。颈部的背侧和侧面有厚厚的脂肪垫，而颈动脉和颈静脉深埋在颈部，并在侧面受到脂肪的保护。食管被一层厚厚的脂肪组织鞘包围，而口咽腔在其与腭骨部分之间有一层脂肪层，为盐腺和脑颅提供了进一步的腹侧隔热。
