How Long Can Hermit Crabs Stay Underwater

How Long Can Hermit Crabs Stay Underwater?

Hermit crabs are fascinating to watch, aren’t they? You might’ve seen them scuttling in your tank, playing hide and seek among the rocks. But have you ever wondered, “How long can hermit crabs stay underwater?” Is it a matter of hours or days, or can they even live a mermaid’s life, forever submerged?

Hermit crabs, both land and sea types, need a balance of air and water. They can’t stay underwater indefinitely as they can drown if fully submerged for prolonged periods. However, they do require regular, brief dips in shallow water to keep their gills moist for proper respiration.

Confusing? Don’t worry! If you’re scratching your head about your hermit crabs’ aquatic needs, we’re here to dive into their world together. Ready to learn? Let’s go!

What Do Hermit Crabs Eat?

Hermit crabs are omnivores with a diverse diet in the wild. This means they don’t limit themselves to a plant- or meat-based diet – they enjoy both!
Depending on their habitat and type, their food preferences vary significantly.

  • Land Hermit Crabs: Land-dwelling hermit crabs eat decaying wood, fallen fruit, leaf litter, worms, and small crustaceans. They also consume organic waste, thereby playing an important role in nutrient recycling in their ecosystem.
  • Marine Hermit Crabs: Marine hermit crabs feed on plankton, detritus, and organic debris. They also eat small fish, worms, and other small marine animals. Some even consume algae, which can help control algae growth in aquariums.

In captivity, both land and marine hermit crabs can be fed a balanced diet of fresh fruits and vegetables and protein sources like fish, shrimp, or commercially prepared hermit crab food.

But, just like us, they require variety in their diet to ensure they get all the necessary nutrients. Calcium-rich food or supplements are also crucial for a hermit crab’s health, as they need it for shell growth.

How Long Can Hermit Crabs Stay Underwater?

How Long Can Hermit Crabs Stay Underwater

Hermit crabs dwell primarily on land but can spend time underwater. They are not true aquatic organisms, requiring both land and water environments to thrive.

This leads us to another interesting question: Can hermit crabs breathe underwater?

Hermit crabs breathe through gills that function differently from those of fish. The gills must remain moist but not continually submerged, creating a need for both aquatic and terrestrial habitats.

There are two common types of hermit crabs, and the duration they can stay underwater varies.

1. Land Hermit Crabs

Land hermit crabs can submerge in both fresh and saltwater for 20 to 30 minutes. This process helps them moisten their gills, regulate salt intake, and even assist in molting.
However, if submerged for too long, they can suffocate, as their gills won’t absorb the necessary oxygen.

2. Marine Hermit Crabs

Unlike their land-dwelling counterparts, marine hermit crabs have adapted to breathe underwater. However, they still require periodic access to air to prevent their gills from dehydration.

How Long Can Saltwater Hermit Crabs Live Out of Water?

Hermit Crabs Live Out of Water

Saltwater hermit crabs, or marine hermit crabs, are usually found in shallow coastal areas.

Adapted to life in the ocean, they breathe using gills that need to be underwater to function. Though capable of briefly leaving the water, they cannot stay out for extended periods. Their gill structure can only extract oxygen underwater.

When removed from the water, they can keep their gills moist by sealing their shells with their bodies, thereby trapping a small amount of water around their gills. But this is a temporary survival strategy. The trapped water eventually evaporates, especially in warm or dry conditions.

The exact duration a saltwater hermit crab can survive out of water depends on its size, environmental temperature, humidity, and the water it can trap in its shell.

However, typically marine hermit crabs survive out of water for about a day to a few days as long as their gills stay damp.

Note: Just because they can survive out of water for a period doesn’t mean they should. It’s stressful for the animal, and prolonged exposure to such conditions will result in death. If you’re keeping marine hermit crabs, you must provide them with an environment that matches their natural habitat as closely as possible.

Can Hermit Crabs Survive in Freshwater?

The survival of hermit crabs in freshwater varies with their type.

1. Land Hermit Crabs

Land hermit crabs need both fresh and saltwater sources in their environment. Saltwater aids in maintaining its osmoregulatory balance and for the successful molting process.
On the other hand, they use fresh water for drinking and bathing. Still, they cannot live permanently submerged in a fully freshwater environment.

2. Marine Hermit Crabs

Marine hermit crabs are true aquatic species. They require saltwater to breathe, maintain their osmoregulatory balance, and survive.

Therefore, marine hermit crabs cannot survive in freshwater as the lack of salt can disrupt their osmotic balance, potentially leading to fatal health complications.

However, you can treat the freshwater with sea salt and dechlorinating products. Only then can saltwater crabs survive in it.
Once the water is prepared, and the crabs have had time to acclimate, they can indeed live in freshwater.

3. Freshwater Hermit Crabs

Freshwater hermit crabs are the only ones known to be truly freshwater and fully aquatic. However, they are rare and not typically kept in home aquariums.

Related article: Why Do Hermit Crabs Burrow ?

How Long Can Hermit Crabs Stay Out of Water?

How Long Can Hermit Crabs Stay Out of Water

Different species of hermit crabs have varied abilities to stay out of water.

1. Land Hermit Crabs

Land hermit crabs can stay out of the water as long as they can keep their gills damp and their environment is sufficiently humid. Typically, it takes around 14 days for the water in their shells to dry out.

2. Marine Hermit Crabs

Marine hermit crabs can only withstand a few minutes out of water. Extended periods outside water can cause dehydration, stress, and eventually death.

Frequently Asked Questions (FAQs):

How long should I submerge my hermit crab in the water?

To keep your hermit crabs healthy, give them a bath of about 30 minutes two times a week. Use a small bowl and fill it with treated water at room temperature, only about a quarter of an inch deep. Carefully place your hermit crabs in the bowl, ensuring the water level doesn’t exceed a quarter of their shell height.

Can hermit crabs drown in water?

Due to their need for air, hermit crabs can, unfortunately, drown if kept underwater for too long.

How long can hermit crabs live?

If cared for properly, Hermit crabs can live for almost 15 years in captivity. However, they can live longer in their natural habitat, up to 30 years.

Can hermit crabs swim in water?

No, hermit crabs cannot swim. They can walk along the bottom of a shallow water source to moisten their gills but can’t swim like a fish. They may drown if the water is too deep.


To summarize, how long hermit crabs can stay underwater depends on the specific species. Land hermit crabs can only stay underwater for short periods (20 to 30 mins). In contrast, marine species can stay underwater indefinitely, although they periodically require access to air.
Despite not being natural swimmers, these intriguing creatures necessitate regular interaction with water. Yet, care should be taken not to submerge them completely for extended periods. Like us, they need a balance of air and water to live their best lives!