Sponges are non-mandatory items you may wish to add to a hermit crab tank.
Natural sea sponges enable hermit crabs to drink and bathe, reducing the risk of drowning and acting as an emergency shell. They’re also helpful for increasing the humidity of the tank.
Sponges must be cleaned or replaced because they attract bacterial microbes. You can’t use kitchen sponges. Instead, get a natural sea sponge from an aquatic pet store.
Purpose of Sponges for Hermit Crabs
| 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. | Almost all pet hermit crabs started life in the wild, living on a beach. This means 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 hermit crabs. However, this can be avoided by providing a way to get out of the water. |
Drinking Water
Absorbing water from a natural sea sponge is less messy and moistens gills.
However, wild hermit crabs drank from puddles or the sea. Drinking from a bowl adequately replicates these conditions. Moreover, it’s easier to provide safe salinity levels through salt water.
Hermit crabs drink by scooping water with their primary claw and transferring it to their mouths. They also store water in their shells, so they have a hydration source while burrowing or during molting.
Hermit crabs enjoy bathing, which could leave substrate and waste floating in the water.
Bathing
Hermit crabs risk drowning. According to the Biological Journal of the Linnean Society, terrestrial hermit crabs breathe air, which means they can’t hold their breath underwater indefinitely.
However, you’ll need to provide fresh water and saltwater bowls. The hermit crabs will climb into these bodies of water, moistening the skin and gills and killing parasites like mites.
Hermit crabs will eventually need to exit the water. If you have pet hermit crabs of varying sizes, the smaller ones may struggle to exit a bowl. If left submerged for too long, they’ll drown.
A hermit crab could use a sponge to rub itself down or as a platform to exit a water bowl.
Food
Natural sea sponges are a nutritional source for hermit crabs.
According to Marine Ecology Progress, sponges contain protein and an energy source. Wild hermit crabs don’t eat sponges, suggesting they have defense mechanisms that deter interest.
This doesn’t apply in captivity because pet hermit crabs often nibble on sponges.
Advantages of Sponges
The benefits of adding a sponge to a tank include:
Tank Humidity
An enclosure with less than 80% humidity leaves hermit crabs at risk of suffocation.
Unfortunately, any increase in humidity is marginal. Even the best sponge will only raise the humidity by around 3%, so you must regularly mist the tank.
Emergency Shell
According to Invertebrate Biology, some hermit crabs use sponges 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, making quality shells desirable.
Recreation
Hermit crabs climb over sponges, push them around a tank, and rip them up. Tearing up a sponge with their claws gives hermit crabs something to occupy their time.
Disadvantages of Sponges
The negatives of putting a sponge in a tank include:
Bacterial Hazard
Bacterial microbes 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 eat sponges, so they ingest harmful bacteria.
Mess
Sponges make the tank look untidy. Of course, you could hide the sponge, 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 gather bacteria.
Further Expense
Natural sea sponges won’t leave you with much change from $5. As sponges need to be changed regularly, you’ll need at least 2-3. The money could be used to provide recreational toys.
How To Clean A Natural Sea Sponge
The best way to clean a hermit crab sponge is with chlorine.
Apply chlorine to the sponge, removing any traces of algae. Chlorine is deadly to hermit crabs and must be cleaned off. To do so, boil some filtered or bottled water and leave the sponge in boiling water.
Then, remove the sponge and allow it to sun dry. Once dry, put the sponge in the microwave for 10-15 seconds for further sterilization. Don’t microwave a damp sponge because it’ll shrink.
Ideally, a hermit crab’s sponge should be changed every 3 to 4 days. Also, replace a sponge that isn’t fit for purpose. This would apply if it doesn’t retain moisture or breaks apart without resistance.
