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First published online August 14, 2009
Journal of Experimental Biology 212, 2753-2759 (2009)
Published by The Company of Biologists 2009
doi: 10.1242/jeb.026500

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Fat head: an analysis of head and neck insulation in the leatherback turtle (Dermochelys coriacea)

John Davenport^1,2,*, John Fraher³, Edward Fitzgerald⁴, Patrick McLaughlin⁴, Tom Doyle^1,2, Luke Harman¹ and Tracy Cuffe³

¹ Department of Zoology, Ecology and Plant Science and Environmental Research Institute, University College Cork, Distillery Fields, North Mall, Cork, Ireland
² Coastal and Marine Resources Centre, University College Cork, Naval Base, Haulbowline, Cork, Ireland
³ Department of Anatomy, University College Cork, College Road, Cork, Ireland
⁴ Radiology Department, Mercy Hospital, Cork, Ireland

^* Author for correspondence (j.davenport{at}ucc.ie)

Accepted 3 June 2009

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°C despite encountering surface temperatures of ca. 15°C and temperatures as low as 0.4°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.

Key words: leatherback turtle, cranial insulation, blubber, gigantothermy

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