When creating a habitat for hermit crabs, 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, reducing the risk of drowning and acting as an emergency shell. However, sponges need to be cleaned and replaced because they attract bacteria.
You can’t use basic kitchen sponges because they contain deadly chemicals for hermit crabs. Instead, get a natural sea sponge from an aquatic pet store.
Should My Hermit Crabs Have a Sponge?
Sponges serve two main purposes:
- Making drinking and bathing safer
- Increasing humidity in a tank
This is beneficial, but sponges aren’t considered mandatory.
What Do Hermit Crabs Use Sponges For?
Pet stores claim that hermit crabs use a sponge for drinking and bathing. Some may take this further, claiming that hermit crabs housed without a sponge may die, but this is untrue.
| Myth | Fact |
| Sponges can replace water bowls for drinking and bathing. | Drinking water is needed, with or without a sponge. |
| Hermit crabs don’t know how to drink without a sponge. | 99% of captive hermit crabs started life in the wild, living on a beach, so they managed to drink and stay alive. |
| Hermit crabs will drown in water and must bathe with a sponge | Drowning is a risk for land crabs, but this can be avoided by providing a way out of the water. |
Do Hermit Crabs Drink Water from Sponges?
Lapping at water could leave hermit crabs with wet mouths, and absorbing water from a sponge is cleaner and keeps the gills moist. However, hermit crabs survived without sponges in the wild.
There, they would have drank from puddles or the sea, and drinking from a bowl replicates these conditions. Moreover, it’s easier to provide safe salinity levels through salt water.
Hermit crabs drink by scooping water from a bowl with their primary claw and transferring it into their mouth. Many hermit crabs also store water in their shell, so they have a source of hydration while burrowed, such as during molting.
Hermit crabs like to bathe, as they dislike feeling unsanitary, which could leave substrate and waste floating in the water. Sponges are less likely to suffer from such base uncleanliness.
Do Hermit Crabs Bathe with Sponges
One of the dangers faced by small hermit crabs is drowning.
As explained by the Biological Journal of the Linnean Society, terrestrial hermit crabs breathe air, which means they can’t hold their breath underwater indefinitely.
Hermit crabs like to bathe by submerging themselves in water, so you’ll need to provide fresh water and salt water bowls. The hermit crabs will climb into these bodies of water, which moistens the skin and gills and kills parasites like mites.
Naturally, hermit crabs may need to make a rapid exit. If you have pet hermit crabs of varying sizes, the smaller ones may struggle to escape a bowl, and if left submerged for too long, they’ll drown.
A sponge is certainly safer, as a hermit crab could use it to rub itself down. Also, a sponge may be used as a platform to exit a bowl.
Do Hermit Crabs Eat Sponges?
Sponges can be a source of nourishment for hermit crabs.
As per Marine Ecology Progress, sponges contain protein and energy. It’s claimed that wild hermit crabs don’t eat sponges, suggesting that they have defense mechanisms that deter any interest.
However, this doesn’t appear to be the case in captivity, as pet hermit crabs often nibble on sponges.
Advantages of Sponges for Hermit Crabs
The benefits of adding a sponge to a hermit crab’s tank include the following:
Increased Tank Humidity
An enclosure at less than 80% humidity leaves hermit crabs at risk of suffocation.
Unfortunately, you may not have been told that any gains in humidity are marginal. Even the best sponge will only increase the humidity by around 3%, so you must regularly mist the tank.
There are alternatives to sponges to increase humidity. Moss is effective, as hermit crabs can eat it. If you use creature soil as a substrate, this contains moss as standard.
If you’re still struggling to generate enough humidity, cover the top of the tank with Saran wrap.
Emergency Shell
As per Invertebrate Biology, some hermit crabs use a sponge as an emergency shell. This behavior is most likely in young, nervous hermit crabs that live in a sizable colony.
All hermit crabs prefer a solid shell, which makes quality shells a desirable commodity among hermit crabs. Males, in particular, often battle for supremacy, with the winner taking the loser’s shell.
Males grow quickly, undergoing several molts in their early years. Each time hermit crabs molt, they grow larger and require a new shell. If they covet the shell of another hermit crab, it’ll look to claim it.
Recreation
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, tearing apart a sponge in no time.
Disadvantages of Sponges for Hermit Crabs
The negatives of putting a sponge in a hermit crab’s tank include the following:
Bacterial Hazard
Bacteria will multiply, as it’s a damp object in a humid environment. Hermit crabs push sponges around their enclosure, meaning substrate, waste, and uneaten food will cling to the sponge.
Hermit crabs often eat sponges, so they risk unwittingly ingesting bacteria.
Mess
Sponges can make the tank look untidy, as you’ll need a large sponge that takes up a lot of space.
Of course, you could hide the sponges, but it’ll still look off. Equally, the sponge may become out of sight, out of mind. If you forget about a sponge, it’ll sit and gather bacteria.
Expense
Hermit crab sponges aren’t cheap, so you won’t get much change from a $5 bill for one small sponge.
As sponges need to be changed regularly, you’ll need at least 2-3. The money you spend on sponges could be redirected to toys and peripherals.
How To Use A Sponge in A Hermit Crab Tank
If you remain undeterred, the best place to put a sponge in a hermit crab tank is in a water dish. Hermit crabs need fresh water and salt water, not tap water.
As per the Bulletin of Environmental Contamination and Toxicology, chlorine and heavy metals in tap water will kill hermit crabs. Getting a water filter or bottled water is recommended.
How To Clean A Hermit Crab Sponge
The most effective way to clean a sponge is with chlorine. Liberally apply chlorine to the sponge, removing any traces of algae.
As discussed, chlorine is deadly to hermit crabs, so it must be cleaned off. To do so, boil some filtered or bottled water and leave the sponge in this boiling water.
Then, remove the sponge and allow it to sun dry. Once dry, put the sponge in the microwave for a few seconds for further sterilization. Don’t microwave a damp sponge because this will cause it to shrink.
Ideally, a hermit crab’s sponge should be changed every 48 hours. Also, replace any sponge that’s no longer fit for purpose (it doesn’t retain moisture or breaks apart without resistance).
