Can turtles sleep underwater?
Want the TL;DR answer? Yes. Yes, they can. You’re welcome, call again. Or stick around if you want to know more.
Turtles sleeping underwater is actually one of the coolest things. They tend to sleep for between 4-7 hours at a time, and this is real sleep, not the appearance of sleep – it’s the time when turtles rest.
One of the weird-but-cool things about turtle sleep is that during these periods, they will occasionally bob their heads up to the surface to take breaths – but that won’t usually interrupt their sleep, any more than you rolling over in the night will necessarily wake you up.
Let Sleeping Turtles Lie
Turtle sleep is more interesting than most people think – at least, it is to us! Let’s take a look at what happens when turtles sleep.
If you’ve watched a turtle sleep, you’ll know they can be picky about the temperature in their zonk-zone. In fact, tank-turtles tend to pick a spot and return to it time after time if they want to sleep.
They do something similar whenever possible when they’re underwater. They find a spot they like, and claim it.
Now, while it’s cool that they sleep for a handful of hours at a time, and while it’s true that this is when they rest, it would be a mistake to think of turtle-sleep as being like our REM sleep.
Sorry to burst any fantasy dreams, but turtles probably don’t dream of what tomorrow’s turtling will bring. If we’re going to anthropomorphize it at all, it’s more akin to a kind of meditative, calm state, which allows them that ability to pop up to the surface to refill their lungs as and when necessary, and then return to their sleep-spot.
There’s something in this notion, because when they’re asleep, their metabolic rate slows right down, which means they use oxygen more efficiently – hence the extended periods underwater on single ‘breaths.’
That’s probably the most intriguing thing about turtles sleeping underwater – the fact that what allows them to do it is similar to a meditative state that slows their bodily processes down and makes them more efficient than they would otherwise normally be, either on land or in water.
It’s hardly surprising that researchers class these sleeps as the true periods when turtles rest and recuperate.
The rules of turtle-sleep also change from type to type. Even people who’ve regularly observed freshwater turtles probably won’t have witnessed them sleeping. They have a preference for burying themselves in the sand or mud at the bottom of a pond to get their sleep.
This takes the underwater sleeping thing to a whole new level, because the way their shell is constructed – and one other interesting biological oddity, about which, more later – means they can get the oxygen they need from the water around them.
That means, with a combination of their slowed-down metabolism and the oxygen in the water, freshwater turtles can survive in the underwater sand for not just hours but months.
Not for nothing, if we could consistently do something similar to our metabolic rate, it would significantly aid us in any future long-haul spaceflight.
Some other turtles prefer a sleep-spot closer to the surface – though they still usually prefer to be hidden under rocks, pieces of wood, or other concealers.
We assume this is an evolutionary strategy, because while most creatures need rest, no creatures other than predators feel especially safe taking that rest out in the open whey can be easily detected by hungry carnivores.
The Owner’s Duty
That habit translates into a duty incumbent on any turtle-owners. If they were in the wild, they’d be able to take care of their sleeping arrangements for themselves.
Having taken them out of their natural environment and brought them into ours, it’s up to us to provide our turtles’ enclosure with everything it needs to get the rest that is part of its natural cycle.
What does that entail? Your turtle will be looking for an easily accessible zonk-zone, probably in a shallow area. Maybe partially submerge a log, leaving a good amount of potential airspace underneath.
Ideally, have plenty of easily accessible materials nearby, so it can hide itself more efficiently during its sleep. That way, your turtle can hide itself and get the rest it needs as and when it feels like.
This is both the turtle’s interests and the owner’s. While we’re not suggesting it’s like crossing a co-worker before they’ve had their first cup of coffee of the day, you don’t want to live life with a cranky, sleep-deprived turtle. And besides, it’s the right thing to do.
You’re going to ask about the hibernation thing, aren’t you?
Turtles are a species split by hibernation. Some, as you’ll know if you own them, hibernate on land, in the manner of several other creatures, building a kind of nest out of leaves, twigs, and anything else that takes their fancy. So far, so turtle, so big whoop.
But aquatic turtles, like the freshwater turtles we mentioned earlier, hibernate underwater, often through the winter. Sometimes they have very little option, if for instance, their favored pond has an ice layer on top of it. Once you’re down beneath that ice, you’re down for a while.
Again, they will bury themselves in the mud or sand at the bottom of a pond – even your garden pond if you have one – and stay there till the cold weather shows signs of warming up again.
And yes, that thing you heard on the Discovery channel is true: while aquatic turtles are hibernating underwater, they will technically ‘breathe’ through their butts.
Nature, people. It’s freaking amazing.
The idea is that because their oxygen needs are so low while their metabolism has been radically slowed down in hibernation-sleep, they can get what’s called ‘uptake oxygen’ from the water around them as it passes over places on their body that are flush with blood vessels.
Want to take a guess where turtles have a whole lot of blood vessels?
Yep – their butt. Technically, their cloaca, but let’s not split hairs this close to a turtle’s butt.
So by this ‘butt-breathing’ technique, turtles can not only sleep underwater – they can stay there for seemingly ridiculously long periods of time.
Do not try this at home, unless you too are a turtle with a very clever cloaca.
Spoiler alert – you’re not.