While most pet stores sell land hermit crabs as an easy pet to take care of, they can be fairly delicate little creatures. Most pet stores will tell you they just need a pool of water, a sponge for humidity, a shell for food, some gravel or calci-sand, and maybe a little coconut to hide in, usually all crammed in a small plastic “tank” with a slotted lid.
In reality, hermit crabs, like any other animal, need a better habitat than that to thrive truly. I can’t think of any animal (apart maybe from some insects) that I would keep in a home like that on anything but a very temporary basis.
We do have one, as that is what the place we originally got our first hermit crabs recommended. Now we use it as a carrier if we need to transport just a few of our hermit crabs, or as an isolation tank if one of them is sick or suddenly aggressive.
Items in bold below are things you will need to purchase to create a really good habitat (habitat!) for your crabs. Click HERE for a printable shopping list.
40-gallon breeder habitat
The best cage for a land hermit crab is a glass or plexiglass aquarium with a glass or plexiglass lid. It does not need to hold water, so old or leaky aquariums are perfect! Hermit crabs are crustaceans who breathe through a system of modified gills, so they need their habitat to be both humid and warm.
Glass holds in warmth and moisture much better than plastic. The other common type of cage you see sold for hermit crabs are metal cages. While on the surface this might seem like a good solution (light, portable, and instant climbing surface), not only does it not hold in any heat or moisture, but it’s made of metal, which land hermit crabs are very sensitive to. They should never be kept in anything but a glass tank in the long term.
Since I mentioned heat and humidity, the perfect temperature for most land hermit crab species is 78°F, with approximately 78% humidity. A good temperature range runs from 70° -83°F, and about the same range of % humidity. If the habitat falls out of that range, the crabs may become lethargic, or they may even go “naked” (run around without a shell).
A few species, most notably the Coenobita perlatus, or strawberry hermit crabs, prefer a slightly higher temperature/humidity, though it should still never be above 85°F/85% for long periods of time. When exposed to prolonged extreme heat or dry air, crabs may die. Because this is a delicate balance to keep, it is very useful to have a thermometer and hygrometer in your tank.
For these reasons, you will also need an under tank heater (UTH), which will attach to the bottom or side of your tank. Be sure to buy one made specifically for terrariums, and at an appropriate size for your tank. Most UTHs will come with little plastic “feet” to stick under your tank to give them circulation space, so they are not a fire hazard. If they do not, you will either need to find something to keep the UTH from being a fire hazard, or you will need to place it on the back of the tank.
If you have a larger tank (more than 29 gal), you may have to supplement the UTH with a low wattage light in an aquarium hood, but be very careful and make sure the tank is at a stable temperature and humidity before moving the crabs in as lights can dry the air out. It is also very important to provide your hermit crabs with appropriate day/night cycles, so never keep a day light on at all times. Either use a timer or use a moon light bulb at night.
One thing that we use and find very helpful is a rheostat with an external probe. The probe goes into the habitat, and the gauge is dialed to turn off at the high end of the appropriate temperature scale. Once heat sources like lights and under tank heaters are plugged into it, it will turn them off if the temperature in the habitat becomes higher than the specified temperature.
Land hermit crabs need a substrate they can dig in. Hermit crabs stay at a comfortable temperature by moving to cooler or warmer areas of the tank or digging down under their substrate. Good substrates include play sand, aragonite, calci-sand and coconut fiber bedding (which is sold as Eco-Earth or Forest Bedding, among other brands). These can be used exclusively, mixed, or put in as separate sections of the substrate.
Since we first got our hermit crabs, we have used all of these substrates at various times. So far, my favorites have been aragonite and coconut fiber bedding. However aragonite is very expensive (about $20 for 10 lbs.) unless you catch it on sale somewhere, and we’ve found it works well mixed with playsand, which tends to be finer than aragonite.
Play sand is probably the best cheap alternative (about $3 for 50 lbs), but it can harden if it dries out, especially under the water dish. Both coconut fiber bedding and sand (excluding calci-sand) should be kept damp so that they will contribute to maintaining your habitat’s humidity.
Sand should be kept at sand castle consistency, so it is damp but not mucky. This can be maintained by dumping small amounts of water on sand. Coconut fiber bedding can be kept damp by misting it occasionally.
To promote mold resistance, make your coconut fiber bedding using a dechlorinated salt water mixture (I usually use a solution of the dechlorinated fresh water and dechlorinated salt water I keep on hand for the crabs’ pools anyhow).
Our crabs dig a lot of holes and tunnels in the aragonite and play sand, but when molting seems to prefer the coconut fiber bedding. We have had successful molts in the sand, but when both were offered, every molt we had was in the coconut fiber substrated.
While calci-sand may work as a substrate, it has several drawbacks. It molds easily and smells bad and clumps when it gets wet. It can work well in a small area of your tank if it’s kept fairly dry, but overall if you must have it, it works best as a calcium supplement fed in a food dish or feeder shell.
Substrates that should NOT be used for land hermit crabs include cedar chips, any wood shavings (especially pine!), potting soil, regular dirt from your garden/yard, crushed walnut shells, and gravel.
Aquarium gravel may be OK as a substrate in a small part of your tank, but it should not be used as the main substrate since hermit crabs cannot easily dig in it, and water tends to pool under it. I will note that organic potting soil, in pots, can be put in the habitat if you have a real plant you’d like to add (and the hermit crabs will snack on it!).
Nonorganic potting soil may contain pesticides or other chemicals that might be harmful to your crabs. Coconut fiber bedding will also support most plants that tolerate damp, tropical climates, though, so a pot and soil may not be necessary unless your coconut fiber is very salty.
Water Source and Supplies
A water dish for fresh water and a water dish for salt water. These dishes should be nonmetallic and deep enough that the crabs can dip their shells in it if they want, but shallow enough that they can still easily get out of the water.
Once again, strawberry hermit crabs are a little special here: they require that their salt water dish is deep enough for them to submerge, but not much deeper.
If you are worried about smaller crabs, be sure to add a something for them to cling to and ways for them to get out of the water, or add a sloping bottom using aquarium gravel or some other surface they will be able to grip and pull themselves out with around the edges.
Despite using modified gills, land hermit crabs cannot breathe for long periods of time under water and will drown if they’re submerged too long. If water dishes are deep enough for them to get water in their shells, hermit crabs will not need to be regularly bathed, since they will be able to do it themselves!
The chlorine, chloramines, and other heavy metals found in tap water are bad for hermit crabs and can cause lasting damage if they are exposed to them for extended periods. All their water should be treated with a dechlorinating solution that does not say it promotes a slime coat in fish.
Salt water must be made with a de chlorinating solution and sea salt. Table salt contains man made iodine, which is poisonous to crabs with prolonged exposure. Sea salt can be readily bought in the aquarium section of any pet store. For most crabs, you should use the package directions for hatching brine shrimp.
However, strawberry hermit crabs require a higher salinity. It’s better to make the solution a little too strong than too weak, as the crabs will regulate the salinity in their shells by diluting the salt water with fresh water.
You should also have at least one undyed sea sponge in the fresh water tank. This will help raise the humidity levels in your habitat. It is nice to have more than one, so you can switch the sea sponge out about once a week, so you can clean it and let it dry, so there is less chance that it will mold.
I have never seen a store that carries hermit crabs NOT have these. Once a sponge is dry, it can be microwaved for a few seconds to sterilize it, but it should never be microwaved while wet – they’ll shrink!
Another big essential is for your crabs to have someplace to hide from the day. You will find lots of ideas in the reptile section of the pet store, or you can get creative. We have caves, half logs, coco-huts (made from half a coconut with a door cut in), aquarium decorations, fake plants, reptile moss, and driftwood for our hermit crabs to hide in.
You can also make a cheap hiding place for them with a small terra cotta pot turned on its side and half buried in the substrate. Be creative! So long as it’s clean, nonmetallic, not made from pine, and not likely to chip paint or other potentially toxic substances into the habitat, it’s probably fine for your crabs! Each crab should be able to find a fairly roomy hiding spot during the day – they will pile together if they want to, but they shouldn’t have to.
Hermit crabs may get lethargic if they are bored, so save room for some TOYS (which often double as hiding spots, handily enough). They love to climb, so anything that will give them purchase will entertain them. Driftwood, caves, coco-huts, cholla wood, even terra cotta pots will turn into climbing toys for your hermit crabs.
If something looks like it will be too slippery to climb, you can drape a fish net over it or otherwise make grooves on the surface. It doesn’t take much for a hermit crab to be able to climb! But be careful about putting things too close to the lid, as they are cunning little escape artists, and are much stronger than they look! Strawberry crabs, in particular, need lots of things to play with, climb, knock over, and destroy.
While only partially decorative, another thing you must obtain for the tank is extra shells about the right size for your crabs. A good rule of thumb is that every crab should ave at least two choices about the same size and weight as their current shell (or slightly bigger). Shells should not be cracked or chipped if possible. If extra suitable shells are not provided, a hermit crab may attack or even kill another hermit crab for its shell.
Any habitat needs a food dish as well. I use various scallop shells (and occasionally other similar flat shells) as food dishes, and I usually keep two in the tank at a time, one with either a treat or a calcium source, and one with a commercial or homemade dry food mix.
These can be elaborate, attached to plastic trees, grapevine, or other tank decorations for your hermit crabs to climb on, or they might be just simple seashells. For a larger tank or more crabs, you may want to add more food dishes or obtain a bigger food dish. For some larger food items, like shrimp or bits of fish, I also have a larger ceramic food dish for the crabs to climb into and eat.
The only other supply you should need is food, which will be explained in more detail on the feeding page.