Turtles that are used to living outdoors can survive the winter in your pond, just like koi and goldfish.
How do they do it?
Well, as one researcher so eloquently put it, they breathe through their butts.
Yep. Nature is weird.
Turtles have some incredible biological tricks that help them survive conditions that will kill most other animals. Here's everything you need to know:
At a Glance: How Pond Turtles Survive the Winter
- Outdoor turtles often spend winter underwater, where temperatures are relatively stable.
- Most turtles' metabolisms slow in winter to the point where they don't need much food or oxygen.
- Turtles can absorb oxygen from water through their skin.
Let's go back to elementary school science class for a moment.
Turtles are ectotherms - a fancy word for cold-blooded. That means their body temperatures match that of their environment. If the water is cold, then so is the turtle's internal temperature. This biology is different from that of warm-blooded animals, which need to constantly generate body heat.
Being cold-blooded in winter sounds rough, but it's actually what helps turtles survive. As their body temperature lowers, so does their metabolism. And a low metabolism means less need for food and oxygen.
Most freshwater turtle species survive the winter by submerging themselves in water. Only a few species can survive being completely frozen, so many dive below the frost line of your pond, where the temperatures remain relatively consistent. They might occasionally swim to the surface for food or oxygen, but they'll generally stick to the water until spring.
How can turtles stay underwater so long? That's where butt breathing comes in.
Turtles have lungs and require oxygen to breathe. In the winter, though, their oxygen needs drop considerably. They absorb the little bit they still need from the water through their skin - specifically, the blood-vessel-dense area around their cloaca.
The cloaca is the all-purpose final stop at the end of the turtle's digestive track. (Other reptiles, as well as birds and fish, have a similar setup.) Because this area is so rich in blood vessels, the turtle can use it to take in oxygen from the surrounding water in winter and doesn't need to use its lungs.
The scientific term for this process is cloacal respiration - and it only works in winter. In warmer weather, turtles can actually drown if they stay underwater too long because they need a lot more oxygen to survive.
Painted Turtles: The Masters of Cold Weather
Painted turtles - one of the most widespread turtle species in North America- are especially adept at handling the cold.
Adult painted turtles can survive in water as cold as 37 degrees Fahrenheit without food or oxygen for up to 100 days. These conditions would kill most vertebrates in three or four minutes.
Many turtles, however, can survive in extremely low oxygen conditions because of their ability to change their blood chemistry. And painted turtles can survive even longer than most.
While hibernating mammals break down fat stores to survive the lack of food in winter, turtles break down a blood sugar called glycogen. This process creates a build-up of lactic acid in the turtle's body. Lactic acid is the stuff that causes muscle soreness in humans after we work out, but for turtles, it can turn deadly.
Some turtles neutralize the acid by borrowing chemicals from their shells and skeletons - kind of like a natural Tums. Painted turtles are the undisputed masters of this skill and can survive longer than other turtles in low- to no-oxygen environments.
Remember: the ability to survive extreme oxygen depletion is unique to painted turtles. Most other pond critters - including your pond fish - need good gas exchange in order to survive the winter.
Tips for a Healthy Winter Pond
Ecosystem Ponds are easy to care for and beautiful to look at any time of year.
Here are some tips for keeping everything running smoothly in the cold months:
Do I need to shut down the whole pond in winter?
Whether or not you shut down your pond in winter is up to you.
If you like hearing your waterfalls year-round, you can keep them running. The water runs through your pipes fast enough to prevent the plumbing from freezing.
For the most peace of mind, however, we recommend winterizing your pond. With the pump off, you don't have to worry as much about water loss or other issues.
Regardless of whether you winterize the entire pond, you still need to turn off your autodoser if you have one and move it to a frost-free location.
Stop feeding fish
Your fish enter a semi-dormant state called torpor during cold weather. They don't need to eat while in this state, so any food you give them will either sit in their bellies (bad for the fish) or sit in the bottom of the pond (bad for your water.)
Stop feeding your fish when water temperatures are consistently below 55 degrees. You can ease your fish's transition into and out of winter with Cold Water Fish Food. Check out our seasonal feeding guide for more information.
Your fish don't eat in winter, but they do breathe.
Install an aerator to add some much-needed oxygen to your pond and to help keep a hole open in any ice that forms on the surface. An aerator is especially important if you decide to shut off your waterfalls for the season.
If your pond ices over, gently create a hole to let oxygen into the pond and bad gases out. Don't use blunt force to break the ice; anything too jarring could injure your fish. Instead, place a deicer or pot of hot water on top of the ice to gently melt it. You can also - carefully - cut a hole with a rough-toothed saw.
Speaking of deicers ...
Deicers are floating heaters that keep a small hole open in an otherwise iced-over pond. These heaters are small enough that they won't raise the overall temperature of your pond, and their thermostatic controls ensure they're only running when they need to be.
Deicers are a great addition to your winter pond care arsenal. With a deicer running, you know a hole will always stay open in your iced-over pond - even if your aerator fails.
Always use a deicer in addition to an aerator - not in place of one. If you can only afford one or the other, an aerator should be your first priority.