.................................Sea Turtle Thermoregulation

An endothermic reptile?


Hypothermic Stunning



Regional Blood Flow

Metabolic Rate




Green turtle, photo courtesy of Caroline Rogers
Sea turtles are ancestral reptiles, originating in the lower Mesozoic era (146-65 Million Years Ago). They are among the largest and longest-lived of all reptiles, highly active for their size, and more migratory than other large reptiles. Their lifestyle is almost exclusively marine; they surface briefly to breathe, and females emerge annually to nest (Lutz 1985).
There are seven species of sea turtle, six of which are found off the coast of the Americas. The flat back turtle (Chelonia depressa), found off the coast of Australia, will not be included in this website, though it may have similar thermoregulatory physiology. Of the remaining six, the leatherback (Dermachelys coriacea) is the largest, at 1000 kg, and migrates over the longest distance (Spotila, et al, 1991). The green turtle (Chelonia mydas) is roughly 150 kg. My website will focus primarily on these two species, as more in-depth information is available on them. However, the four other American species, Kemp’s Ridley (Lepidochelys kempi), Olive Ridley (Lepidochelys olivacea), Loggerhead (Caretta caretta), and Hawksbill (Eretmochelys imbricata) thermoregulate in much the same way as the leatherback and the green turtle.


Hawksbill, photo courtesy of Claudia Townsend

This website will explain the physiology of sea turtle thermoregulation in their marine environment. As nesting takes place on land under completely different conditions, concerns only females and hatchlings, and occurs only once a year, I will not discuss the thermal aspects of nesting in this website.

Sea turtles are neither purely ectothermic nor purely endothermic. While they use their surroundings both to increase and decrease their body temperature, they depend as well on internal physiological mechanisms in heating. Their endothermic characteristics depend greatly on their large size, and as a result the leatherback is more endothermic than the other, smaller, sea turtles.

Human activity affects sea turtles and their native oceans, bays, estuaries, and nesting beaches. Bycatch, intentional capture and consumption, and habitat destruction are causing a rapid decline in sea turtle population, the full of effects of which may not be seen until it is too late. Sea turtles’ long life-span and late sexual maturity disguise the fact that juvenile survival rate is not high enough to sustain healthy populations in the future.

Me and a green turtle

For more information on sea turtle ecology and conservation please visit the links found in the sources page. It’s not too late!

Me about to release a green turtle

Next: An endothermic reptile?


This web site was completed by Katie Fitzpatrick in partial fulfillment of the requirements for Dr. Michael Dorcas's Biology 312, Animal Physiology, at Davidson College in Fall Semester 2005.

Visit other students' websites.

Please direct all comments and questions to Katie Fitzpatrick at kafitzpatrick@davidson.edu