Editor’s note: This is part of a series highlighting the seven species of sea turtles during #SeaTurtleWeek. A different species will be highlighted each day. For more information on other Sea Turtle Week activities offered by the Sea Turtle Preservation Society, please go to our website or visit us on Facebook and Instagram.
As their name implies, leatherbacks have a shell unlike any other species of sea turtle. Leatherbacks have a rubbery skin stretched over a flexible cartilage layer, which allows the sea turtle to dive deep – to depths of 4,200 feet. Leatherbacks swim faster, further, and deeper than any other species of sea turtle.
Another adaptation, a countercurrent heat exchange system in its limbs, allows the leatherback to survive in deep, cold water that other sea turtles would not. This system allows a leatherback to conserve body heat through a tight network of arteries and veins in its limbs. With a countercurrent heat exchange system, warm blood in the arteries transfers heat as it flows past the veins before the veins lose heat through the skin’s surface. In this way, cold blood doesn’t flow back to the heart and lower the turtle’s core body temperature. If the sea turtle is too warm, the heat transfer can be reversed to cool its core body temperature.
Thick layers of fat surrounding the muscles also help with controlling a leatherback’s body heat. The fat layer works as an excellent insulator in cold water; and, in warm water, a network of blood vessels that allows blood to flow past the fat to the skin’s outer edges can release heat. This is why a nesting leatherback’s throat may turn pink.