A lot of people consider adding hermit crabs into their fish tanks as these crustaceans belong to what aquarists call the cleanup crew. Although these animals aren’t true crabs, they’re pretty popular because they are curious, fun, and quite easy to care for.
But do hermit crabs live in water? Can they swim, or will they drown if they get submerged in water?
Read more to find the answers to these questions and learn more about hermit crabs.
There are two main types of hermit crabs. Both of them need water to survive, but they breathe differently.
Marine hermit crabs spend most of their time underwater, but they can temporarily survive out of the water. This usually happens when the animals are ready to mate or when they’re searching for food.
Some types of marine hermit crabs spend all their lives underwater, and never go to land.
Land hermit crabs spend most of their time on land, but they can survive temporarily in water. Land crabs need access to saltwater and freshwater to breed and survive.
Both types of hermit crabs use gills for breathing, but land hermit crabs can’t stay underwater for too long. So instead, they prefer to live in high-humidity conditions or to keep their gills moist.
Without access to water, land hermit crabs will become too dry, and they won’t be able to breathe, so they suffocate. These animals also need access to salt from saltwater to help with their periodical molting process.
As a result, they usually keep some water in their shells to keep their gills damp.
Marine hermit crabs need to keep their bodies and gills moist, too. The ability to survive outside water differs between different species of marine hermit crabs.
Marine hermit crabs spend most of their time in the water, but their bodies aren’t designed for swimming.
These animals breathe through gills but spend their time on the ocean floor.
Land hermit crabs can tolerate being in the water, but they don’t swim. As a matter of fact, they avoid getting submerged in deep water, so they have no reason to swim.
Both marine and land hermit crabs have ten legs. Some of them have claws, while others don’t.
The front legs have tiny claws and are usually used for scooping food into the crab’s mouth. However, they’re also used for self-defense, so the crab will use these legs to pinch you if you’re not careful while handling it.
The second and third pair of legs carry the crab’s weight with the shell. The third pair of legs also allow the crab to get in and out of its shell.
The rest of the legs are rear legs, and the animal uses them to clean the shell and its gills.
Although the front legs might help with swimming, they’re actually too few to propel the crab’s body to the front.
The rear legs are too short and not suitable for swimming. In addition, they don’t have knee joints, so they don’t bend like the legs of other crabs.
Most marine crabs prefer to live in shallow water and walk on the ocean floor to reach land when needed. They also feed on sea snails, algae, and corals, so they don’t need to spend much time on land and won’t be interested in swimming to get out of the water.
Moreover, being concealed and hard to see on the ocean floor is essential for these animals’ survival. When they swim, they might accidentally encounter bigger predators like sharks and whales.
Marine hermit crabs are good climbers, so they’ll climb rocks, reefs, and any other structures they can find to reach land, whenever it’s necessary.
Both marine and land hermit crabs have gills.
Marine crabs can breathe through their gills, so they can spend all their lives underwater, although in some cases, these animals prefer to go to the shore for brief periods.
Land crabs have modified gills. As a result, they can’t breathe the air, and they’ll drown if they stay underwater for too long.
So, land crabs need access to humid air to be able to breathe.
They wet their gills to keep them moist, and then they fill their lungs with air.
When they go underwater, they hold their breaths. If they spend too much underwater, the animal’s lungs will fill with water and die.
Marine hermit crabs can breathe underwater, and they can still breathe out of the water as long as their gills are kept moist.
Land hermit crabs also have gills but are less developed and more disadvantaged.
They also breathe through gills, but they’re smaller and stiffer than the ones found on marine crabs. These gills need to be moist, but when they’re submerged in water for too long, the oxygen in the lung gets mixed with water, and the crab dies.
Nevertheless, land crabs can survive being submerged by holding their breaths. These animals are known to hold their breaths for up to 60 minutes.
However, this ability depends on the crab’s species, as some species are known to hold their breaths for short periods.
Marine and land hermit crabs need access to freshwater and saltwater to survive.
Marine crabs can live in a freshwater tank, but you must provide them with a saltwater dish.
These animals need the minerals and salts in saltwater to stay healthy and be able to molt. So, while they can definitely survive in freshwater, providing access to saltwater is crucial.
If you’re setting up an enclosure for your hermit crabs, you can make your own saltwater by mixing water with the sea salt that you buy for fish and other crustaceans.
Land crabs won’t submerge themselves in water, but providing a bowl of freshwater and another one for saltwater will help them thrive.
These animals need water to keep their bodies moist, wash themselves, and moisten their gills.
Marine hermit crabs won’t drown when they’re underwater. These animals spend most of their lives on the ocean floor, so they won’t drown when they’re kept in a water tank.
However, they still occasionally need to step out of the water, so you need to provide them with climbing structures if they want to spend some time on land, as they do in the wild.
Land hermit crabs, on the other hand, can definitely drown. They need to survive in humid conditions because they can’t breathe dry air.
Nevertheless, too much water will fill their lungs with water, so they’ll suffocate and drown.
If you’re keeping land crabs in a terrarium, you need to make sure that they have water dishes or pools.
However, the water shouldn’t be too deep, as these are terrestrial animals.
Marine hermit crabs can stay underwater all their lives. Of course, they would appreciate being able to get out of the water whenever they need to, but you don’t have to get them out of the water.
Some of these species live close to the shore, so they’ll occasionally wait for the flow of tides to bring them closer to land. These animals usually do this for mating purposes.
Once they’re done, they wait for the ebb to take them back to the water.
However, in an enclosure, marine crabs can survive all their lives underwater. Yet, having access to land will definitely be a plus.
Land hermit crabs are less tolerant of staying underwater.
There are different types of land hermit crabs, and some of them can survive underwater for longer periods.
On average, land marine crabs can survive underwater for between 20 and 30 minutes. However, some species can stay alive while being submerged underwater for up to 60 minutes.
Younger crabs will always struggle more than they’re kept underwater. Most immature crabs will only survive for about 10 minutes underwater.
Hermit crabs can live in tap water as long as it’s dechlorinated.
The chlorine found in tap water can kill hermit crabs, so it should be removed from the water before adding it to the crab’s enclosure.
If you’re unsure about your crab’s favorite water requirements, you can add freshwater and saltwater and let it decide.
In most cases, crabs need access to both types of water.
Untreated tap water can kill your hermit crabs, so you need to make sure that it’s safe before using it as drinking water and in food preparations.
Fluorines, chlorines, chloramines, and heavy metals might be present in tap water, and these chemical compounds can potentially kill crabs.
You can dechlorinate the water using several methods. The first one is to just leave the water overnight. This will allow most of the chemical compounds to evaporate.
You can also boil the water and let it cool before using it.
The fastest way to treat tap water is to use a conditioner. This safe chemical compound makes tap water healthy and ready for use.
You can use tap water for cleaning the crabs’ enclosure, but you should dry it well before adding treated water.
Terrestrial or land hermit crabs usually live near the shoreline. Some species spend the early stages of their lives underwater, but then they spend most of their time on land when they mature.
Other species spend less time in the water but prefer to have access to water pools near the shoreline.
These animals need water pools for bathing, drinking, and wetting their gills. They also carry some extra water in their shells.
Land hermit crabs need to keep their gills and bodies moist to be able to breathe. So, without access to water, these animals will suffocate.
However, they don’t spend their lives underwater like other species of aquatic hermit crabs.
Land hermit crabs can spend extended periods underwater by holding their breaths. Yet, they’re unable to breathe underwater like marine hermit crabs.
If the land crab gets too deep into the water and is unable to return back to the shore, the animal will die.
Land and water hermit crabs prefer to stay in cool dark locations to keep their gills moist and protect their bodies from drying out.
They also hide to protect themselves from predators so they’re able to survive under the sand.
Marine crabs usually live in tidal environments, so although they will be submerged in water at high tides, they’ll get exposed to the air at low tides.
This is why these animals prefer to hide under the sand to keep themselves undetected.
Land and marine hermit crabs also hide under the sand while they’re molting and can stay there for weeks or even months until the molting process is over.
Pet crabs also dig a hole in the substrate and stay hidden until they’ve completely gotten rid of the old exoskeleton.
In the wild, hermit crabs will usually explore different sites before choosing one to dig. Then, the animal digs a tunnel to keep itself undetected but will still have access to air and a way out when it’s done.
If you’re setting up a tank for your hermit crab, investing in specialist aquarium sand is best because it imitates the crab’s natural habitat. Generic playground sand is also OK, as long as it won’t collapse and suffocate the crab.
Marine hermit crabs spend most or all their lives underwater, but they can occasionally spend some time on land. However, some species are entirely aquatic and never go to the shore.
Land hermit crabs need access to water to keep their bodies and gills moist. These animals can’t breathe dry air, but they’ll drown in water.
Land crabs are unable to breathe underwater, but they’ll hold their breaths when they get submerged. The ability to hold their breaths differs from one species to another and depends on the crab’s age.
I have a bachelor’s degree in Film/Video/Media Studies, as well as an associates degree in Communications. I began producing videos and musical recordings nearly 15 years ago. I am a guitarist and bassist in Southwest MI and have been in a few different bands since 2009, and in 2012 I began building custom guitars and basses in my home workshop as well. When I’m home, I love spending time with my three pets (a dog, cat, and snake) and gardening in my backyard. I also like photographing wild birds, especially birds of prey.