Can sea turtles breathe underwater?

Question

ORP · Accepted Answer

Sea turtles cannot breathe underwater, however they can hold their breath for long periods of time. Sea turtles can hold their breath for several hours depending on their level of activity. For instance, a resting turtle can remain underwater for 4-7 hours whereas a foraging individual may need to surface more frequently.

When turtles hold their breath, their heart rate slows significantly to conserve oxygen - up to nine minutes may pass between heart beats! Despite this adaptation, a stressed turtle - such as one entangled in ghost net - will deplete oxygen stores rapidly and may drown within minutes if unable to reach the surface.

Underwater image of a green turtle popping its head above water for a breath, Maldives. Image. — A green turtle popping its head above water for a breath, Maldives.

A green turtle resting on a reef, Kenya. Adopt a turtle in Kenya. Image. — A green turtle resting on a reef, Kenya.

References:

Long dive interval during hibernation: Hochscheid S, Bentivegna F & Hays GC 2005. First records of dive durations for a hibernating sea turtle. Biology Letters 1: 82-86.
Dive duration during activity: Hays GC, Akesson S, Broderick AC, Glen F, Godley BJ, Luschi P, Martin C, Metcalfe JD & Papi F 2001. The diving behaviour of green turtles undertaking oceanic migration to and from Ascension Island: dive durations, dive profiles and depth distribution. Journal of Experimental Biology 204: 4093-4098.
Hays GC, Hochscheid S, Broderick AC, Godley BJ & Metcalfe JD 2000. Diving behaviour of green turtles: dive depth, dive duration and activity levels. Marine Ecology Progress Series 208: 297-298.