what do hermit crabs use sponges for?

Do Hermit Crabs Need Sponges?

When creating a habitat for hermit crabs, a thick layer of substrate, hiding places, climbing apparatus, and bathing water are all non-negotiables. However, sponges are an extra that you may wish to add to their home.

Sponges enable hermit crabs to drink and bathe safely. They reduce the risk of drowning and may act as an emergency shell. Sponges need to be cleaned and replaced as they attract bacteria.

You cannot use basic kitchen sponges for your hermit crabs as they contain chemicals that are deadly for your hermit crabs. Instead, you need to get a natural sea sponge from a specialist pet store.

Should My Hermit Crabs Have a Sponge?

It is claimed that sponges serve two main purposes:

  • Making drinking and bathing safer
  • Increasing humidity in a tank

This sounds highly beneficial, but sponges are not considered mandatory. In fact, sponges are likely to cause more problems than they resolve.

What Do Hermit Crabs Use Sponges For?

Pet stores may claim that hermit crabs use a sponge to drink and bathe. Some may take this a step further, claiming that hermit crabs housed without a sponge may die, but this is untrue.

Sponges can replace water bowls for drinking and bathingHermit crabs need to drink water, regardless of whether a sponge is provided
Hermit crabs do not know how to drink without a sponge99% of captive hermit crabs started life in the wild, living on a beach. They managed to drink and stay alive in the wild
Hermit crabs will drown in water and must bathe with a spongeDrowning is certainly a risk for land crabs. You can minimize this risk by providing an easy means of exit from bathing water.

Do Hermit Crabs Drink Water from Sponges?

Lapping at water could leave hermit crabs with wet mouths. Absorbing water from a sponge is cleaner and keeps the gills moist.

Remember though, your hermit crabs survived without sponges in the wild. There, they would have drunk from puddles, or simply the sea. Drinking from a bowl replicates these conditions. What’s more, it’s easier to provide safe levels of salinity through saltwater.

Hermit crabs drink by scooping water from a bowl with their primary claw. This water is then transferred to the mouth. Many hermit crabs also store water in their shell. This means that they have a source of hydration while burrowed, such as during molting.

Water bowls can get dirty. Hermit crabs like to bathe, as they dislike feeling unsanitary. This could leave substrate and waste floating in the water. Sponges are less likely to suffer from such base uncleanliness.

do hermit crabs drink water from sponges?

Do Hermit Crabs Bathe with Sponges

One of the biggest dangers to face small hermit crabs is drowning. As explained by the Biological Journal of the Linnean Society, terrestrial hermit crabs breathe air. This means they cannot hold their breath underwater indefinitely.

Hermit crabs like to bathe by submerging themselves in water. This means that you’ll need to prove both fresh water and saltwater baths. The hermit crabs will climb into these bodies of water. This moistens the skin and gills and kills parasites, such as mites.

Naturally, hermit crabs need to be able to make a rapid exit. If you have pets of varying sizes, smaller hermit crabs may struggle to escape a bath. If left submerged for too long, they will drown.

A sponge is certainly safer, in this case. Your hermit crab could use the sponge to rub itself down. This is like using a washcloth rather than using a bath. A sponge may also be used as a platform to exit a bathtub.

Do Hermit Crabs Eat Sponges?

Sponges can be a source of nourishment for hermit crabs. As per Marine Ecology Progress, sponges contain protein and provide energy.

This journal also claims that wild hermit crabs avoid feeding on sponges. This suggests that these lifeforms have defense mechanisms to deter interest. This does not appear to be the case in captivity as pet hermit crabs often nibble on sponges.

As intimidated, there is no harm in this habit. Sponges could even be considered a healthy snack. The same can be said of other foods, though.

Advantages of Sponges for Hermit Crabs

You may decide to introduce a sponge into the habitat of your hermit crabs. Let’s explore the pros and cons of placing a sponge in a hermit crab tank.

Increased Tank Humidity

One of the main selling points of sponges is that they increase humidity in a tank. This is certainly vital. An enclosure at less than 80% humidity leaves your hermit crabs at risk of suffocation.

Unfortunately, what you may not be told is that these gains are marginal Even the finest sponge will only improve the humidity by around 3%. You’ll still need to mist the tank regularly.

There are alternatives to sponges to increase humidity for your hermit crabs. Moss is effective, and like sponges, can be eaten by hermit crabs. If you use creature soil as a substrate, this contains moss as standard.

If you are still struggling for humidity, cover the top of the tank with Saran wrap. This will trap moisture within. We’re not denying that sponges increase humidity. There are just more cost-effective ways of doing so.

Emergency Shell

As per Invertebrate Biology, some hermit crabs use a sponge as an emergency shell. This behavior is likeliest in young, nervous hermit crabs that live in a sizable colony.

All hermit crabs prefer a solid shell. This makes high-quality shells a desirable commodity among hermit crabs, though. Males, in particular, often battle for supremacy, with the winner taking the loser’s shell.

This is because males grow quickly, undergoing several molts in their early years. Every time that hermit crabs molt, they grow larger and require a new shell. If they covet that worn by another hermit crab, especially a smaller one, it will look to claim it.

Sponges a safe solution for non-confrontational hermit crabs. Sponges are not a sustainable cover, though. If you notice your hermit crabs wearing sponges, offer them a range of new shells.


Your hermit crabs may use a sponge as a toy. It’s essentially just another obstacle. Hermit crabs will climb over sponges, push them around a tank, and tear them to shreds for amusement. 

Tearing up a sponge will give hermit crabs something to do. The primary claw of a hermit crab is powerful. It will make short work of a sponge. This will provide at least a few minutes of entertainment.

Disadvantages of Sponges for Hermit Crabs

For every benefit of using a sponge, there are drawbacks. Weigh these up before committing to putting a sponge to a hermit crab enclosure.

Bacterial Hazard

The biggest risk of sponges is that they are hotbeds for bacteria. It is a damp object in a humid environment that will quickly start to attract mold and other undesirable elements.

As discussed, hermit crabs often eat sponges. Ergo, you are at risk of your hermit crabs ingesting deadly bacteria without even realizing it. This is among the most common explanations for sudden death in hermit crabs.

Hermit crabs push sponges around their enclosure. This means that substrate, waste, and uneaten food will cling to the sponge. That does not lend itself to a clean living arrangement.


Sponges can be an eyesore in an enclosure. In short, they make the whole tank look untidy. To gain any real benefits, you’ll need a large sponge that takes up a lot of space or multiple small sponges.

Of course, you could try to hide the sponges. Placing them under the substrate will still look off, though. There will be a lump that cannot be ignored. Equally, the sponge may become out of sight, out of mind. If you forget about a sponge, it will simply sit and gather bacteria.

As discussed, hermit crabs also enjoy tearing sponges apart. This will make spot cleaning of the substrate increasingly laborious. You may grow weary of picking out pieces of sponge before they start to rot.


There is no getting around the fact that hermit crab sponges are expensive. The money you spend on sponges could easily be redirected. Alternative toys and peripherals will be equally helpful, if not more so.

You will not get much change from a $5 bill for one small hermit crab sponge. As these sponges need to be changed regularly, you’ll need at least two or three. Think about all the things you could spend that $15 on and decide if sponges are a worthy use of your funds.

How To Use a Sponge in a Hermit Crab Tank

If you remain undeterred, the best way to use a sponge in a hermit crab tank is by placing it in a water dish. Hermit crabs need both fresh and saltwater. They enjoy having the choice.

If you are only using one sponge at a time, place it in the saltwater dish. This is the hydration source that they are likelier to gravitate toward.

How Often Should You Wet a Hermit Crab Sponge?

If your hermit crab uses a sponge as a water source, it must always be wet. Do not use tap water to douse the sponge, though.

As per the Bulletin of Environmental Contamination and Toxicology, the presence of chlorine and heavy metals in tap water will kill hermit crabs.

Getting a water filter is the cheapest solution, while bottled mineral water is even safer. If the sponge looks dirty, it must be cleaned and replaced.

how often should you wet a hermit crab sponge?

How to Clean a Hermit Crab Sponge

The easiest way to clean a sponge is through chlorine. Liberally apply this to the sponge until it is clean. This means removing any traces of algae.

As discussed, chlorine is lethal to hermit crabs, so it must be cleaned off. To achieve this, boil up a vessel of filtered or bottled water. Leave the sponge in this boiling water for as long as possible.

Remove the sponge and let it air dry in the sun. Once dry, pop the sponge in the microwave for a few seconds for further sterilization. Do not microwave a damp sponge, as this will cause it to shrink.

If it appears safe to do so, return the sponge to circulation within the tank. If not, repeat the process. If the sponge is still unclean after two cycles, throw it away.

When Should a Hermit Crab Sponge be Replaced?

In an ideal world, a sponge should be changed daily. If this is not an option, change it every 48 hours at worst. This means that you will need an array of sponges. You’ll require a constant rotation while sponges are being cleaned.

Leaving a sponge in an enclosure for longer than 48 hours is dangerous. The likelihood of bacteria attaching itself to the sponge is high. If you cannot commit to changing sponges this often, avoid them altogether.

You should also replace any sponge that is no longer fit for purpose. This means a sponge that cannot retain moisture or breaks apart without resistance. Sponges become hazardous if you continue to recycle them.