Famous for being slow, you might not think that snails are a particularly interesting group of animals. We are going to try and challenge this view by looking at one of their most unique behaviors: sleep.
We don’t tend to think about other animals sleeping. Many sleep at the same time as humans, so you don’t get a chance to see it, but snails have a more complex process.
They are becoming very popular for home aquariums. Not only do they offer a different look to fish, but snails are one of the best algae eaters around. With more people getting snails, more people are wondering why they spend so much time sat still.
Snail Sleep Overview
Sleep is a big part of our lives. It can vary dramatically between animals, and snails in particular have a unique system. They are famous for being one of the slowest creatures in the animal kingdom, even when they are active they sit still most of the time.
If you keep freshwater snails at home, you might have noticed prolonged periods of inactivity. Some people assume the worst, thinking that their pets are dead, but they are likely just asleep.
The way they sleep isn’t as simple as sleeping at night and being active in the day (which most of us do). It’s also different to how fish sleep – most fish are diurnal, like humans.
Sleeping comes with a big risk because while we’re unconscious, we’re completely vulnerable. This is more of a problem for wild animals that have to worry about nearby predators.
Fish can regulate their sleep and stay alert, so they can react quickly if a predator is nearby. This isn’t an option for snails because they move so slowly. Instead, they have a shell which offers a form of protection until they wake.
As less complex organisms than us, snails are less dependent on sleep. This means that their patterns and habits are much different.
How Do Snails Sleep?
They can sleep pretty much anywhere. A sticky mucus lets them climb over all surfaces in the tank. This mucus is used to hold them in place while they sleep. So snails can sleep in any position – sideways or even upside down.
They carry their home on their back for protection, so they can stop to sleep wherever they happen to be (decorations, tank walls, leaves, or the substrate). Their bed is wherever they want it.
In a well established tank, some individuals begin to show a personality, picking a favorite spot to settle for sleep and returning regularly. Once settled, they relax their foot and tentacles which withdraw slightly. The shell hangs away from the body.
Much of their sleep takes place in the daytime. They are more active at night to avoid the intensity of sunlight.
A sleeping snail can often look like a dead snail, so don’t be too quick to start mourning.
One of the main things that worries owners is seeing their snails float on the surface of the water. Sometimes air can get into a live snail’s shell; this makes it buoyant and rise through the water. Some marine species purposefully use bubbles to float and wait for prey.
To check if a snail is alive, carefully remove it from the water. Signs of death include an empty shell, a foul smell, lack of response to touch, and an open trapdoor on the snail’s body.
How Long Do Snails Sleep?
Snails sleep very differently to other inhabitants of the water. Most fish are diurnal, meaning that they’re active in the day and asleep at night, but snails don’t have a daily schedule.
Instead of a 24-hour sleeping cycle, a snail’s sleep cycle lasts for 2-3 days.
Research has shown that over 13 hours, snails sleep in seven small bouts. After this, there is a 30 hour period where they are active.
If a snail loses sleep for one reason or another, they seem to be able to carry on as normal until their next set of seven bouts.
Snails can sleep for a very long time, via hibernation. It’s reported that this could last for up to 3 years! Few species actually hibernate for this long though, and it’s very unlikely to be seen at home.
Do Snails Hibernate?
Hibernation is common in mammals, especially rodents. It is a process that is usually used to help survive the winter, when temperatures are low, and food is scarce.
It works by reducing metabolic activity to save energy, since food is in short supply. The body temperature is lowered, breathing is slowed, and heart rate decreases. In the wild, freshwater snails hibernate this way, entering a deep sleep during winter until water temperatures rise again in the spring.
You are less likely to see snails hibernate in your aquarium because temperatures generally remain constant. You can trigger their natural hibernation behaviors by lowering your tank’s temperature through winter, but this isn’t necessary.
If you think they are hibernating, add less food into the tank since they will need less energy. Monitor the food. If it disappears quickly, add more, if it ends up sitting on the bottom of the aquarium, give less.
Some animals enter a state called “aestivation”. This is effectively the same as hibernation, but during summertime. Metabolic rates are lowered so the animal can hide away from the dangers of high temperatures, which could dry a snail out.
Aestivation is common in land snails but not aquatic ones (since water can help to buffer high summer temperatures).
Other Fun Facts About Freshwater Snails
- Not only do snails sleep differently, but they also mate differently to fish. Most snails are hermaphrodites, meaning that they have both male and female sexual organs. They still need to pair up for mating though, so that their eggs can be fertilized.
- To move, snails use a “foot”. This is a muscular organ which is constantly expanding and contracting. The foot has a special gland which excretes mucus. The mucus acts as a lubricant and glue, allowing the snail to move across a surface while also sticking to the surface.
- The way that snails breathe can differ between species. Some, like nerite snails, use gills to extract oxygen from the water.
- To eat, snails have thousands of teeth which together form the radula. A single radula could have 120 rows, each of 100 teeth. This is an effective cutting/scraping tool when feeding.
- The southeastern United States hosts the highest number of species, but they’re found across the globe. Another hotspot is Lake Tanganyika, in Africa.
- They don’t have ears, but they have good eyesight to make up for their lack of hearing.
- The largest freshwater species is the apple snail (Pomacea maculata), reaching 6 inches. This is nothing compared to the African giant land snail (Achatina achatina), which is a massive 15.5 inches when fully extended.
- There are approximately 5,000 freshwater snail species living in lakes, ponds, and rivers across the world. All of these are gastropod molluscs, and most fall into the subclass Pulmonata.
FAQs About Snail Sleep
Do Snails Sleep At Night?
A snail’s sleep cycle isn’t diurnal – this means that they don’t just sleep at nighttime. Instead, they sleep over a 13 hour period in seven bouts, which can span day and night.
Can Snails Sleep Upside Down?
Yes. Snails can sleep sideways or upside down, pretty much anywhere they can get a firm grip. They may come unstuck if disturbed though.
How Long Do Snails Sleep For?
Usually sleeps are short (seven separate sleeps within 13 hours) but can be much longer during hibernation. To protect themselves from the cold and preserve energy, a snail could hibernate for up to 3 years.
This length of time is species dependent though, common aquarium species don’t hibernate for anywhere near this long.
People don’t tend to think about the complexity of animals. As we watch them we take for granted the simple things like how they sleep. When we stop to think and ask questions (like can fish drown?), the answers are both interesting and surprising.
Now that snails are a common sight in home aquariums, more and more people are realizing how interesting they are. The way that they sleep is completely different to both the fish you keep them with and us as humans.
Their sleep cycle is particularly strange. This cycle is completely switched up in the winter, when hibernation is necessary to avoid the low temperatures and lack of food.
If you keep snails at home then you will probably have seen these strange sleeping habits.
Even though you now know how snails sleep, there is still plenty more to learn about these unique creatures.
Do your snails have any interesting sleeping habits? Let us know what you have seen in the comments below…