Snapping Turtle
| Scientific Name | Chelydra serpentina |
| Survival Strategy | Brumation |
| Conservation status | Least Concern |
Spring
When the water warms in early April, snapping turtles come out of brumation and return to an active lifestyle. Mating can occur anytime between spring and fall, with female snappers able to store viable sperm for several years, which allows them to delay nesting if environmental conditions are not favorable.
Summer
One of the few times these turtles are out of the water is during nesting season, which peaks in mid-June but can continue into mid-summer. Females will travel a kilometer (0.62 mi) or more to find a suitable nesting site. They locate a well-drained sunny spot and bury 20 to 40 eggs in a nest dug into loose soil. Snapping turtle eggs will hatch in 65 to 95 days, typically in late August or early September. The first challenge for the quarter-sized hatchlings is to find their way to the relative safety of the water. Many will not be successful.
Fall
Snapping turtles become lethargic by mid-October, and in colder climates, can spend up to half of the year underwater in a state of brumation.
Winter
Although they are most often inactive, occasionally, you can see snapping turtles moving under the ice of a frozen pond. They will remain in brumation until the water warms in the spring.
Behavior
Bad Reputation
Snapping Turtles can be vicious when out of the water. Anyone who has ever moved a turtle off the road has learned that they will hiss and snap (hence the name ‘snapper‘) as a defensive display. They may also give off foul-smelling urine when picked up. Snapping turtles in the water are shy and pose no threat to swimmers.
Soak Up the Sun
Snapping turtles are cold-blooded (ectotherms) and need to bask in the sun to regulate their body temperature. They typically bask by floating at the surface but sometimes crawl onto a log or rock. Turtles need UV light from the sun to produce Vitamin D, which improves calcium absorption and helps build strong bones and healthy shells. The sunlight kills fungus and creates an unwelcomed environment for sun-hating leeches.
Physiology
Cold Water Protects Turtles from Even Colder Air
Like all cold-blooded animals, a snapping turtle’s body temperature matches its surroundings. It can reduce its metabolism by nearly 99 percent in near-freezing water and survive without food or oxygen for 100 days. The water temperature under the ice stays above freezing, even as winter air temperatures drop below zero. Although cold, the water in a pond protects the turtle from the extreme cold only a few feet above its head. Some cold-blooded animals can survive ice crystals forming in their body tissue; snapping turtles cannot.
I’m not making this up!
Lungs are of no use under the winter ice. Snapping turtles absorb oxygen using cloacal respiration; in other words, they breathe through their butts.
Going Anaerobic
An ice-covered pond or lake will slowly run out of oxygen as winter progresses. At that point, snapping turtles begin to metabolize stored glycogen, which does not need oxygen to release energy. Glycogen metabolism generates toxic levels of lactic acid, which turtles neutralize with minerals released from their shell and bones. This process is similar to the lactic acid buildup that creates sore muscles in athletes.
Gender Determine by Incubation Temperature
The gender of snapping turtles is determined by the temperature in a five-day window during incubation. If within this temperature-sensitive period the eggs are incubated between 23°C (73°F) and 27°C (81°F), the eggs will produce only male turtles. Temperatures outside this range will produce both male and female turtles, and extreme temperatures, warmer or cooler, will produce only female turtles.
Diet
Snapping turtles eat crayfish, fish, frogs, other turtles, small mammals, and newly hatched waterfowl. Aquatic plants make up to one-third of the turtle’s diet. They are opportunistic omnivores and consume almost anything they can fit in their mouths. They will also take on the role of a scavenger, eating carrion when they find it.
Snapping turtles cannot swallow food while on land because they use the pressure of the water to help move food down their esophagus.
Lifespan and Mortality
Adult snapping turtles live around 30 years, while some have reached 100 years. The first few weeks after hatching are the most dangerous for young turtles. The chances of surviving from hatchling to adulthood are less than 1%.
Predators
Adult snapping turtles have few predators. Great blue herons, crows, raccoons, skunks, foxes, bullfrogs, water snakes, and larger fish eat turtle eggs and hatchlings. One study found turtle mortality from road kills was over 10%.
Climate Vulnerability
Rising temperatures could benefit young snapping turtles. Because snapping turtle eggs hatch in late summer, warmer temperatures would give hatchling snapping turtles more time to grow before they spend the winter under the ice.
A warmer climate could reduce, or eliminate, the number of male turtles in some parts of their range.
Never stop learning
First Nations: The Ojibwe word for snapping turtle is “mikinaak.”
Geography: Snapping turtles are considered an invasive species west of the Rocky Mountains and are the state reptile of New York.
References
| Jackson DC, Ultsch GRy. 2010. Physiology of hibernation under the ice by turtles and frogs. J. Exp. Zool. 313A:311–327. https://onlinelibrary.wiley.com/doi/pdf/10.1002/jez.603 |
| The secret to turtle hibernation: Butt-breathing https://www.pbs.org/newshour/science/the-secret-to-turtle-hibernation-butt-breathing |
| Bosch, A. 2003. “Chelydra serpentina” (On-line), Animal Diversity Web. https://animaldiversity.org/accounts/Chelydra_serpentina/ |
| The Common Snapping Turtle, Chelydra serpentina, Rylen Nakama, FISH 423: Olden 12/5/14https://depts.washington.edu/oldenlab/wordpress/wp-content/uploads/2015/09/Chelydra_serpentina_Nakama_2014.pdf |
| A.R. Hedrick, H.M. Klondaris, L.C. Corichi, M.J. Dreslik, and J.B. Iverson. The effects of climate on annual variation in reproductive output in Snapping Turtles (Chelydra serpentina). Canadian Journal of Zoology. 96(3): 221-228. https://doi.org/10.1139/cjz-2016-0321 |
| Video: Snapping turtles dangerous? Swimming with snappers! https://youtu.be/8xKVS4IkP6w |
| The Ojibwe People’s Dictionary: Snapping Turtle https://ojibwe.lib.umn.edu/main-entry/mikinaak-na |