Butt Breathing of a Snapping Turtle

My Pawpaw speared the chicken neck on a sharp stick about 2-feet long. He squatted down, asked his son if he was ready, and pushed the morsel toward the snapping turtle. The turtle shot his head out to grasp the chicken exposing a good amount of his neck. That is the moment that my uncle swung the razor sharp machete down, cleanly severing the turtle’s head. Therein lies the beginning of a good turtle soup, and my early encounter with the harsher side of nature meets human.

I know that this is an extreme way of presenting the common snapping turtle (Chelydra serpentina). Growing up on the Texas-Louisiana border along the Gulf Coast, we ate our share of wild foods. Actually, turtle farms in the U.S. export between 200,000 and 300,000 snapping turtles to East Asian markets annually. Even combined with low hatchling survival, road mortality, and habitat loss the International Union for Conservation of Nature’s Red List of Threatened Species shows the common snapping turtle as Stable and of Least Concerned1.

Why the name “snapping” turtle?

Unlike most other turtles the snapping turtle has a small underside (plastron). This limits how far it can pull in its tail, legs, neck, and head. Its strong jaws and large beak snaps in defense. These assist in grabbing and tearing food into bits.

snappingg turtle with open mouth
Fig. 1

The species reference serpentina stems from its “snake-like” tail and neck. It can easily extend its neck the length of its body, up to 19-inches. This makes it a formidable hunter, and biter. If you happen upon one crossing the road, let it be. If you feel the need to help it along, there is a way to mitigate the chance of a bite or scratch. If you have a box, you can gently push it along into the box using a broom or shovel. Once inside, carefully move it to the other side of the road and tump it out. Remember, snapping turtles are lightening fast defenders. I do not advise picking one up. However, if you must, here are some guidelines from Tufts Wildlife Clinic2.

How hard can it bite?

According to a study in the Journal of Evolutionary Biology3,4 found that the common snapping turtle has an average bite of 48.8 pound-force. (In comparison, the average bite of a human (molars area) is 112.4 pound-force.) That may not be enough force to bite off one’s finger, but it sure will be painful.

Where does it live?

Found only in North America Its natural range extends from Montana across to southeastern Canada and down south to Florida and stretching across the Gulf Coast into Texas. It prefers an aquatic habitat coming on land around dusk and dawn to hunt. Its favorite ambush tactic is to bury itself in the muddy shallow edge of its watery home. Since its nostrils are at the very tip of the nose, it breathes while being very well camouflaged.  As unsuspecting prey, frogs, other turtles, birds, and small mammals approach, it strikes. However, as an omnivore it will eat just about anything including scavenging dead plants and animals.

snapping turtle closeup of head
Fig. 2

Where does it go in winter?

As an ectotherm — an animal that relies on an external source of heat — a turtle’s body temperature tracks that of its environment. This makes the common snapping turtle incredibly  cold-tolerant. When their aquatic habitat freezes over, the lower section does not.  So, if the water below is 33*F, the turtle’s body temperature matches that. Hibernating snapping turtles do not breathe for extended periods of time. In their northern range that can extend over six months. 

So, how does it breathe?

During hibernation the snapping turtle buries itself in the muddy bottom of its habitat. It “breathes” by transferring oxygen from water as it passes over blood vessels in the mouth and throat, aka extrapulmonary respiration. However, the more efficient method is butt breathing5, aka cloacal respiration. 

Because the cloaca performs several functions including egg laying and waste elimination, it is extremely vascularized containing a myriad of blood vessels. Actually, it is not in a sense breathing as much as the transference of oxygen in and carbon dioxide out through the blood vessels.

Oh yeah. If you really want to make turtle soup, I offer this very good recipe6

bowl of turtle soup
Fig. 3


1((van Dijk, P.P. 2012. Chelydra serpentina (errata version published in 2016). The IUCN Red List of Threatened Species 2012: e.T163424A97408395. https://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T163424A18547887.en. Accessed on 22 February 2023.)  (Small, Leah. Study shows commercial harvest of snapping turtles is leading to population decline. VCU News, Oct. 25, 2017. Retrieved 22 Feb 2023 from https://news.vcu.edu/article/study_shows_commercial_harvest_of_snapping_turtles_is_leading.

2 What to do if you found a snapping turtle. Retrieved 22 Feb 2023 from https://vet.tufts.edu/node/8561

3Lappin, A.K., Wilcox, S.C., Moriarty, D.J. et al. Bite force in the horned frog (Ceratophrys cranwelli) with implications for extinct giant frogs. Sci Rep 7, 11963 (2017). Retrieved 22 Feb 2023 from https://doi.org/10.1038/s41598-017-11968-6 

4Herrel, A., & O’Reilly, J. C. (2006). Ontogenetic scaling of bite force in lizards and turtles. Physiological and Biochemical Zoology, 79(1), 31-42.

5Litzgus, Jacqueline (2017). The Secret to Turtle Hibernation: Butt-Breathing. Retrieved 22 Feb 2023 from https://www.livescience.com/61018-turtles-breathe-through-butt.html.

6Shaw, Hank (2022). Creole Turtle Soup. Retrieved 22 Feb 2023 from https://honest-food.net/turtle-soup-recipe-creole/#recipe.

Photo Credits:

Feature Image: Stukel, Sam/USFWS (2021). Common Snapping Turtle (Chelydra serpentina) on a Walk, [photograph], Retrieved 28 February, 2023 from Flickrs website: https://www.flickr.com/photos/usfwsmtnprairie/51326693493/. Public Doman Mark 1.0.

Fig. 1: Hallman, Bruce/USFWS (2017). Common Snapping Turtle [photograph], Retrieved 28 February, 2023 from Flickrs website: https://www.flickr.com/photos/usfwsmidwest/36290540871/. Public Doman Mark 1.0.

Fig. 2: Smith, Grayson/USFWS (2017). Common Snapping Turtle [photograph], Retrieved 28 February, 2023 from Flickrs website: https://www.flickr.com/photos/usfwsmidwest/48404231872/. Public Doman Mark 1.0.

Fig. 3: Tseng, T. (2015). Turtle Soup, Wild snapping turtle with rich veal fond, crushed lemon, and aged sherry [photograph], Retrieved 28 February, 2023 from Flickrs website: https://www.flickr.com/photos/68147320@N02/. Attribution 2.0 Generic (CC BY 2.0).

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