Key To Survival

PROPER SUBSTRATE TYPE, DEPTH AND MOISTURE CONTENT

The MAIN key to keeping land hermit crabs alive in captivity is to fill your crabitat uniformly with sand deep enough (3-4X their shell size) and moist enough (packs well) that your largest crab is able to bury into complete darkness to molt successfully.

In nature hermit crabs dig underground, when it is time to molt, for two reasons. First, they need the darkness that they get by burying in order for the molting hormone (ecdysone) to be secreted . This hormone is triggered by extended darkness and controls the actual shedding of their exoskeleton (ecdysis). Second, they need the isolation and protection that being buried underground provides them. A hermit crab that has just shed its exoskeleton is unable to move until it hardens up and regains muscle control. During this time they are vulnerable to cannibalism by other crabs and predators if they are not protected. The insulating properties of being buried underground provides protection from the elements and dehydration as well.

The best substrate for hermit crabs is what they would find in the wild typically a moist sandy / soil mixture. To simulate this we advise our customers to cover the entire bottom of their crabitat with a moist mix of clean course grade sand and coconut fiber. Coarse sand packs well and the coconut fiber helps with water retention. Large hermit crabs can stay buried under ground while they molt, for a period of up to 3 months, so the goal is to create deep moist substrate that will take very little care while they are buried. This way you will not have to disturb them while they are most vulnerable.


  • Our first recommendation of course would be to use our Pre-mixed Substrate. We have hundreds of customers using it successfully in their crabitats for over 3 years now. It arrives pre-mixed and moistened, ready to pour in your tank. It packs well, providing good protection for molting crabs.
  • Clean all purpose sand, found in many hardware stores, is another alternative. We have been told by our customers that some all purpose sand is listed as being pet safe. This type of sand is beige/tan in color, fairly course in texture and tends to pack and hold moisture very well.
  • Some Beach Sands work well and contain bits of seashell and natural sea salts that will be beneficial to your crabs exoskeleton health. Again coarser sand seems to work better than fine sugar sand.
  • Play sand can be used as well, although it is not my first choice. Play sand tends to be very light (almost white) in color, more fine than all purpose sand and does not hold moisture as well. If you use play sand make sure that no antibacterial or anti fungal agents have been added to it.
  • You can even use Backyard soil if no pesticides or fertilizers have ever been used on it.

Calcium type sand often sold in pet stores for hermit crabs is not suitable for use in a crabitat. It is very fine, powdery and easily sticks to a hermit crabs moist abdomen not to mention it is typically expensive. It is also designed to be used dry which does not allow hermit crabs to bury and successfully re-surface after they are done molting. One of the benefits touted for this substrate is that it clumps readily to wet waste material. As stated through out this section, your substrate needs to remain moist, making this sand unsuitable.

Using moistened coconut fiber by itself in your crabitat is also poor choice as it provides molting crabs with very little protection increasing the chance of cannibalism. Using a mixture that is primarily sand (5 parts sand to 1 part coconut fiber) is much more protective.

Remember moisture is critical to enable hermit crabs to bury, you will want to maintain "sand-castle making consistency" of your substrate so that your crabs can dig and pack a cave in which to molt. Dry sand will cave in on them as they try to bury. Add purified or even salt water to your substrate mixture as needed to maintain packing consistency. If crabs are buried mist the surface well or use a watering can to keep the substrate moist until they have resurfaced from molting. Then when you are certain that no crabs are buried molting, you can remove everything from the cage, then thoroughly moisten and re-mix your substrate to the perfect consistency so that it is ready for the next molting crab.

SUBSTRATE DEPTH MINIMUM AND MOLT LENGTH DEPEND ON HERMIT CRAB SIZE

Size of crab
(overall - crab and shell)
TEENY
(dime)
(1/2" or less)
TINY
(penny)
(3/4")
SMALL
(quarter)
(1")
MEDIUM
(golf ball)
(1 5/8")
LARGE
(tennis ball)
(2 1/2")
JUMBO
(larger than a baseball)
(3" or more )
Minimum sand depth
6+ inches
6+ inches
6+ inches
6 - 8+ inches
8 - 10+ inches
12+ inches
Molts per year
many per year
many per year
3 - 4 per year
1 - 2 per year
1 per year
1 per year to year and a half
Length of time buried
2 wks.
2 - 3 wks.
1 mo.
1 1/2 - 2 mos.
2 - 3 mos.
3 mos.

Additional Needs