This past summer we had some baby snapping turtles on our kitchen counter in a terrarium. They had been abruptly ejected from their eggs and nest when my mother was using our tractor to spread out the sand pile on the beach beside our pond. We couldn’t leave them to die, so we performed a rescue mission. We did some research when we first brought the turtles in, and we found that it would take about a week for them to absorb the yolk sacks hanging from their bellies. Only then would they be interested in eating. And that’s just how it turned out. Astonishingly, the turtles were doing very well a week, so we thought we might find some tiny earthworms for them. This was easier in our house than most because we have a “Worm Farm” right in our kitchen, with a type of worm called a “red wiggler” which is exactly the right size for a turtle the size of a quarter. The quest to keep these little guys alive and thriving (and we later released them in a swamp near our house) led to a world of research, questions, answers and still more questions. This blog posting was inspired by all we learned about these amazing – largely overlooked - creatures.
Snapping turtles, as we know them today, evolved about 40 million years ago, preceding and out living both dinosaurs and wooly mammoths. Curiously they are the ancestors of about 80% of all the turtles today. Modern snapping turtles have hardly changed for 215 million years. Early snapping turtles (Proganochelys) had most features of today’s turtles, though early turtles were unable to pull their heads and legs into their shells. This amazing staying power is another discovery that inspired me to write this piece. What has kept the snapping turtle alive this long and how do we compare ourselves to their durability?
Before we can analyze the staying power of the snapping turtle, we first have to have a standard to compare to. I came across these 5 keys to survival when I was doing a research project on why the first small mammals survived the mass extinction that wiped out the dinosaurs. Demonstrating the purpose of my independent study at BeyoneTheXtraMile.com, I was able to circle back to that prior knowledge and consider it here in a whole new context!.. What is the secret to evolutionary stability and success? The standard I came up with regarding the first mammals applies here perfectly. It consists of five criteria, which if met means a species will flourish for a long time. In brief the criteria are:
1. Be small so you don’t need a lot of resources.
2. Reproduce quickly.
3. Don’t be a picky eater
4. Be highly mobile and flexible about where you can live.
5. Don’t be fragile under stress. Have a deep bag of survival tricks and backup systems.
If you are small you have a large population you can reproduce faster, allowing for rapid adaptation to new conditions. Also if you are small you do not require as much food to keep going. If you have only one source of food, or need a specific plant to shelter in, then you are doomed. However, if you can eat more or less anything that comes your way, you have a greater chance of survival. If the species has a global distribution, some are likely to reside in a spot that is largely unaffected by the crisis. If you already inhabit multiple habitats, then some will likely be less affected or you can move from one to another. In addition, an animal that can move freely will do well because it can escape the prevailing conditions and carry on. Animals used to going for long periods without food or water or have burrows, are likely to do better than those that require copious clean water, or those that can only survive a few hours in the wrong temperatures.
It was interesting to learn that reproductive success in snapping turtles is highly variable. Predation on nests is extremely high for snapping turtles. An average of 11 to 94 % (though yearly variation is high) of nests are destroyed annually by predators such as: skunks, raccoons, mink, and red foxes. Predation on hatchlings and juveniles is heavy especially during the first year and only slightly lower during the 2nd and 3rd year. However, once snapping turtles reach about 3 inches in length, they have no natural predators and adults may lay many eggs over their long lifetime (80 years) which tips the reproduction balance in their favor. Miraculously, 60% of the turtles that reach adulthood will live to age 50. Brings a new meaning to the advice of listen to your elders, doesn’t it?
In the wild snapping turtles eat almost anything - as long as they can catch it and swallow. The diet of wild young snappers consists mainly of snails, worms, leeches, insects, larvae, small fish, water plants and any edible organic waste that falls to the bottom of the lakes and ponds they call home. Adult snappers eat larger prey as frogs, fish, newts, tadpoles, toads, crayfish, and even snakes, small turtles, small mammals and young birds that happen to be passing by. This may be the single most important trait that allowed the snapping turtle to out- live the dinosaurs and other prehistoric creatures.
The snapping turtle has adapted to be as free moving as an animal with a shell can be. There are two parts to a turtle’s shell: the carapace or the top part and the plastron, which is underneath. The plastron of a snapping turtle is much smaller than in other turtles and is barley connected to the carapace. This means Snapping turtles cannot hide as well in their shells, but it gives them much better mobility and that mobility makes them extremely durable. Snapping turtles are mainly aquatic and the majority of their lives in ponds, creeks or swamps, but they can readily adapt to a wide variety of habitats and are found practically in any permanent or semi-permanent non-moving or slow-moving body of water. Snapping turtles can go for up to 2 weeks without water, which enables them to make long overland migrations, or to swim in the ocean. They can even live in salt water or brackish water but have to periodically return to fresh water to rehydrate. Snapping turtles are one of the few species, which can also live in significantly polluted habitats, including sewer systems. In northern climates, as long as the water depth is great enough to allow them to hibernate below the ice, and cover or camouflage is available, they will thrive. The turtle’s range and flexibility allows it to survive crises in certain climates, where animals that have small ranges would die if their environment were in crisis.
The snapper is no stranger to stress and it is a shining example of how many successful species have developed “backup systems” for their major biological needs. In the case of the snapping turtle they hibernate in the winter in shallow water, buried in the mud in places, which do not freeze. During hibernation the turtle’s body temperature drops to about 34°F. During this time the turtles hardly move, and remarkably do not breathe for more than six months while ice covers their hibernating site. During hibernation snapping turtles can get oxygen by allowing gas exchange to take place through the membranes of their mouth and throat when they push their heads above the mud - extra pulmonary respiration. The snapping turtle’s remarkable ability to last months without taking a breath of air as given it an innate advantage over many other creatures trying to survive the winter in climates as variable as Florida and Canada.
The snapping turtle’s amazing staying power is what inspired me to write this piece, and it has given me new perspective on our own survival as a species. Let’s take one brief moment to look at the way humans have evolved through the same standards. Here’s how I would assess our chances of survival…
1. Be small so you don’t need a lot of resources. Nope
2. Reproduce quickly. Nope
3. Don’t be a picky eater. Yep
4. Be highly mobile and flexible about where you can live. Yep
5. Don’t be fragile under stress. Have a deep bag of survival tricks and backup systems. Yep
We’ve got three out of 5 covered pretty well, but that we are sure out running our resources, so I can’t have confidence in that area. And our slow reproduction is just something we are stuck with. So my advice (if anyone is listening) is for us to take a few pages from the snapping turtles play book and start living more within our means when it comes to resources. The snapping turtle has met all the criteria needed to be successful and survive, but he question on the table now is; Can we?