How long can a hermit crab survive without salt water?

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Hermit crabs need water to breathe because they absorb oxygen from the air through their gills. If their gills dry out, they suffocate and die. So, how long can hermit crabs go without water? To find the answer, we need to divide hermit crabs into two groups: aquatic hermit crabs and land hermit crabs.

Aquatic hermit crabs spend their whole lives underwater. They can only survive for brief periods out of the water. Land hermit crabs live outside of the water, but they do need access to freshwater and saltwater to survive. Land hermit crabs would die in two weeks without these two water sources.

To keep hermit crabs in an aquarium healthy, you have to provide them with an environment that meets all their needs. Water is a key element. In this article, we discuss how different hermit crabs breathe, what their physical needs are and how to care for them in captivity.

Do Hermit Crabs Breathe Water or Air?

Hermit crabs do not have lungs for breathing like mammals and amphibians. They are crustaceans that breathe through modified gills. They are slightly different to fish gills, but they have one thing in common: the gills need to stay moist in order to absorb oxygen.

Both land and aquatic hermit crabs breathe oxygen from the water surrounding their gills. They do not breathe oxygen directly from their air. The gills have to stay wet.

Inside the gills, crabs have a dense network of blood vessels. Oxygen in the water is absorbed by these vessels. The more water surrounding the gills, the more efficiently the crab can take up oxygen.

The reason that land hermit crabs can leave the water and live on land is that their gills are modified. They are able to store water inside their shells to hydrate their gills. Because aquatic hermit crabs do not have the ability to do this, they cannot live outside of water.

If land hermit crabs do not have access to freshwater and saltwater, they will run out of the water inside their shells that they use to keep their gills wet. If their gills dry out, they will die. How long would it take for a hermit crab to die without water?

Land hermit crabs would only survive for up to two weeks without access to freshwater and saltwater. They need saltwater to regulate their respiratory rate, and they need freshwater to keep their gills moist so that they can breathe.

In hot, dry conditions, land hermit crabs would probably not last as long as two weeks.

Aquatic hermit crabs can only survive outside of water for a few minutes at most. When they are out of the water, they are essentially holding their breath.

Hermit Crabs Can Drown!

Hermit crabs cannot cope with too little water or too much. Land hermit crabs can actually drown if they are submerged in water for extended periods.

A land hermit crab can only survive being submerged for 15 to 60 minutes. Younger hermit crabs are not able to survive for as long underwater as larger, more mature crabs.

How to Transport Hermit Crabs

So, if hermit crabs cannot survive outside of water, how should one transport them from the pet store or the beach to your home?

When you buy aquatic hermit crabs from a pet store, they usually come in a plastic bag, just like aquarium fish.

For a short ride home, the plastic bag is perfect, but if you have to drive a couple of hours, you will need a way to keep the water in the bag cool. Put it inside a cardboard box on your seat and wrap it with a towel.

The best way to transport land hermit crabs is inside a cardboard box lined with slightly damp moss. They will survive for a few hours if the humidity in the box is high and it stays cool.

How to Care for Hermit Crabs

Both aquatic and land hermit crabs are fun, easy pets to care for. Here is how to create the perfect environment for your new crustacean companion:

Aquatic Hermit Crabs

Two hermit crabs need at least a 10-gallon aquarium tank. If you have multiple pairs of crabs, a 30 to 50-gallon aquarium is suitable. The tank may be glass or acrylic.

Find a spot to keep the tank where it is out of direct sunlight. You should not put it near a window or close to a heater or radiator.

Fill the bottom of the tank with a substrate, like sand and coconut fiber. The crabs need the sand to burrow into. Avoid using beach sand! The sand must be sterilized before you can use it.

Place some sterile rocks in the tank to provide the crabs with some structure. Buy some “living” rocks from the pet store. These are ones that have beneficial algae growing on them.

Next, fill the tank with store-bought saltwater (or fresh, unchlorinated water, if your crabs are a freshwater species). Slowly acclimate your crabs to their new home before releasing them.

Feed your hermit crabs every day. Try to feed them as diverse a diet as possible. Crab pellets, freeze-dried krill, tiny bits of raw fish, and dried seaweed are great treats for hermit crabs.

Land Hermit Crabs

The tank set-up for land hermit crabs is exactly the same, only you do not fill it with water. Instead, place two shallow dishes of dechlorinated freshwater and store-bought saltwater in the tank. Make sure your crabs will easily be able to climb in and out of the water containers.

You can also place some additional hiding spots in the tank for land hermit crabs – pieces of driftwood, upside-down clay pots, or aquarium décor from the pet store.

Change the crabs’ water every day to keep it fresh. Give them food daily. Keep the temperature of the tank steady at 70 to 80°F.

Final Thoughts

Hermit crabs of all kinds cannot survive long without access to water. Aquatic hermit crabs that are adapted to spending their whole lives underwater can only survive for short periods of time outside of water. If their gills dry out, they suffocate and die.

Land hermit crabs, on the other hand, are adapted to living outside of the water but they still need access to freshwater and saltwater to survive. They also need high humidity levels in their tank. Without access to water for 2 weeks, land hermit crabs will die.

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