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Setting up a proper crabitat

Let’s look at how to set up a proper hermit crab habitat, which we refer to as a crabitat.

Basing your tank set up on what you saw at the petstore or mall cart where you may have purchased your hermit crabs is a recipe for disaster. Kritter Keepers and wire cages are death boxes and should never be used.

Listed below are the primary components of a proper set up and we will discuss them in detail. If you are not willing to equip the tank properly you should return your hermit crabs or rehome them, they will not thrive without a properly set up habitat. Captive hermit crabs can live over 30 years in the proper habitat. Most hermit crabs die either in the first month of ownership, during the first molt of ownership or within the first year to 18 months.  So yes, they can technically ‘survive’ in poor conditions but why on earth would you purposely do this to an animal???

A simple list of the items you will need to properly outfit the crabitat. There are low cost options for most of these items.

  • Tank
  • Lid
  • Light*
  • Heat
  • Substrate
  • Gauges
  • Bowls
  • Climbers
  • Hiders
  • Plants and Vines

The tank itself should be glass or lexan and large enough to comfortably house your hermit crabs. A MINIMUM of 2 gallons of space per small or medium hermit crab but 5 gallons per crab is much more humane. Large and jumbo crabs will need much more space, 10 gallon minimum. A 10 gallon tank is too small for even one large or jumbo crab. Plan for the future when purchasing your tank, allow for the growth of your crabs or additions to the herd.   A used tank is perfectly fine and will greatly reduce the cost of supplies.

The tank must have a lid that retains humidity. A screen lid with glass, lexan or plastic wrap on top is what is typically used. Hermit crabs require humidity to breathe. Opening the lid for feedings and water changes each day usually provides enough air exchange. Fresh air flow reduces mold, mildew and fungus growth.

Light is required, whether they are used as your heat source or not. Hermit crabs require a normal 12 hour cycle of light and dark, it is vital to the molt process. If your crabitat is in a well light room that will meet the need of daytime light. Do NOT place your tank in directly sunlight!

UVB is believed to extend the life span of captive hermit crabs. UVB bulbs must be mounted in such a way that there is no glass or plastic barrier between the bulb and the hermit crabs. Most people mount the lid inside the tank.  Bulbs must be replaced every 12 months.

For nighttime viewing, LED in red or blue is safe. Your hermit crabs do not require a light at night.

Hermit crabs require warm temperatures. This can come from overhead lights or from heat pad (often called under the tank heater or UTH) which is placed on the wall of the tank and not under it. Over head lights or heat emitters are not recommended for inexperienced pet owners. They make it challenging to maintain the correct environment in the tank.

Ways to heat your crabitat

Global Temperature and Precipitation Maps by Month

Gauges are the only way to monitor and maintain proper heat and humidity levels. The tank temperatures should be a range of 75F to 82F.  72F is the absolute minimum and your tank should not remain at this temperature long term. A temporary dip or spike in temperature is not cause for concern. A range means that your tank should have areas of different temperatures. Some species seem to enjoy slightly warmer temperatures but the common clypeatus is happy in the 75-82F range. Check the substrate temperature as well to make sure it is not too hot. Overly warm substrate will kill molters or discourage molting. Humidity ranges should be 70-80% this is relative humidity. Occasional higher humidity is not cause for concern but maintaining excessively high humidity could lead to flooding or lethal bacteria due to over saturation of your substrate. Your analog hygrometer will need to be calibrated before use. Wireless, digital gauges are relatively cheap and are more accurate than analog gauges.

Substrate should be a mix of 5 parts play sand and 1 part eco earth. The ideal mix will keep the sand moist throughout. The consistency should be so that you could easily make a sand castle. That means that molting burrows will not collapse from drying out. We suggest using a brackish water to expand the eco earth bricks. This will help reduce the chance of mold. The eco earth should be DRY when mixed into the sand so you don’t end up with water logged substrate at the beginning. You can always add water once the crabitat environment is stable, if needed. In many cases it is not needed. Starting with too wet substrate will lead to flooding and/or bacterial blooms. Mix your substrate dry, close up the tank with the lid and all the decor and allow it to stabilize for 48 hours. If the humidity is too low you can mist the substrate. Then wait another 24 hours and check the humidity again. It is much easier to add moisture to the substrate than it is to dry it out once it is in the tank.

The eco earth will help maintain humidity but you may need to add some moss pits if your levels are too low. Not all moss is safe so be sure to check our list: Which types of moss are safe for my hermit crabs?

Substrates for hermit crabs

Three bowls will be needed. Two of the bowls should be deep enough to allow your hermit crabs to submerge themselves. One should be fresh water and one should be ocean water made with marine grade salt mix. All water that comes in contact with your hermit crabs must be treated to remove chlorine, chloramines, ammonia as well as other chemicals. The third bowl will be for food. These don’t have to be reptile dishes specifically but they should be something that your smallest crabs can easily enter and exit. Many people use disposable Gladware type bowls for water pools. We recommend placing a rock, fake plant or coral in the pool for the smaller crabs to climb out.

Places to hide, things to climb on, as well as plants and vines are important to create an environment that is stimulating and enriching for your hermit crabs. Huts do not have to be made of coconut shells, many things will work. The same holds true for things to climb on. There are lots of DIY ideas or less expensive ideas for creating vertical climbing opportunities. Fake plants and vines from a craft store will work as well as the ones you find at the pet store. Some live plants are safe for the crabitat but your hermit crabs will most likely kill them.

Creating additional levels in your crabitat to maximize usable space

Your goal should be to create an environment that is as close to what hermit crabs experience in nature as possible. Hermit crabs live primarily on beaches, so think tropical!

Here are some examples of properly set up crabitats:

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Ask Milo – What size tank do I need?

Mattiesse ask:

I am the proud owner of 4 beautiful crabs in Brisbane. the problem is, is that I live in NSW so my other parents in queens land need to take care of them. luckily im bringing them down here but I cant bring the tank, so im gonna have to make a new home. im planning on getting more hermit crabs as well so I need to know how to make the best sized and equipt tank for soon to have not 4 but 6-8 hermit crabs. how big should the tank be and what is the best stuff to get for them so they live a long healthy life!!!

How exciting! The amount of space you need depends on the size of crabs and the number of crabs. Long term you should have 10 gallons of space per crab so you would need at least an 80 gallon tank if you are going to keep 8 hermit crabs. That will give them plenty of space in your crabitat as they grow. You will need a lid that can hold in the humidity, a proper heat source, a day time light and about 12 inches deep substrate (mix of play sand with a bit of cocofiber mixed in). Also food dishes, saltwater and fresh water ponds (deep enough to submerge in), gauges, places to hide and things to climb. Oh and yes a bunch of shells!

For more details check out some of our articles:
Hermit Crab Essentials Shopping List
Newbies Guide to Hermit Crabs

Measuring Hermit Crab Shells

Wee wants to be big so bad

Wee wants to be big so bad

**A newer version of this article is available: http://crabstreetjournal.org/blog/2018/02/11/land-hermit-crab-shell-guide/

Hermit crab shells sold online are typically sold based on the size of the opening. When purchasing new shells for your hermit crab, measure their existing shell and then choose several shells that are somewhat larger. Hermit crabs typically prefer a shell that fits snugly allowing them to fully seal off the opening to protect themselves from predators and dessication.
The photo shows how to take measurements properly.

Measuring hermit crab shells

Measuring hermit crab shells


Ecuadorian (C. compressus) typically prefer a shell with a D shaped opening and commonly wear shells that are too small.
Other species will wear a variety of shells, both with circular and D shaped openings.

HPIM2673

Circular opening shell

 

D shaped opening shell

D shaped opening shell

 

My shell is too small!

My shell is too small!

 

Coenobita cheliped pincer claw

My shell fits just right!

 

FAQ How do I choose suitable shells for my hermit crab?

***Note: There is a newer version of this article:

Land Hermit Crab Shell Guide

 

A hermit crab’s shell is his home and his protection from predators and dessication. Hermit crabs take up residence in discarded shells and can not make their own shell. When kept as pets it is important that you choose suitable shells for your hermit crab.

In semi-terrestrial hermit crabs a well-fitting shell is essential for maintaining low evaporation rates and carrying ample water. An appropriately sized shell in good condition allows invasion of inland environments offering more shade, food and fresh water for C. clypeatus studied on Curacao. Hermit crabs with broken, ill-fitting shells are restricted to the coast, must rely on drinking saltwater, and appear to be in relatively poor condition.[1]

Terrestrial hermit crabs show “shell facilitation”; that is, larger populations of crab generate, through wear, larger numbers of shells suitable for adult crabs. [2]

Hermit crab’s should be allowed to choose the shell they prefer from a selection of different sizes and types of shells. Natural shells are the best option. Painted shells should be avoided. Shells should not have jagged edges or holes in them.

Most species of hermit crabs will prefer a shell with a round opening. Coenobita compressus (Ecquadorian) prefers a shell with a D shaped opening.

Shells should be cleaned and boiled before offering to your hermit crabs. If you collected shells from the beach be sure the shells are EMPTY before bringing them home.

Hermit crabs can be very stubborn about changing shells but do not attempt to force a crab from it’s shell.

Contrary to common belief, a molt does not mandate a shell change! If the existing shell is roomy enough to allow for growth during a molt, the hermit crab may feel no need to change shells. Additionally, you will find some hermit crabs are chronic shell shoppers, always trying on something new.

Hermit crab shells are sold online by the size of opening. To determine the correct opening size measure the opening as shown here:

Measuring hermit crab shells

FAQ How do I choose suitable shells for my hermit crab?


Photos of common hermit crab shells:
Common Hermit Crab Shells

Are hermit crabs looking for lighter and larger shells?
The distribution, abundance and shell selection behavior of three species of hermit crabs
Land Hermit Crabs Use the Smell of Dead Conspecifics to Locate Shells
Coenobita violscens shell behavior
The Social Lives of Hermit Crabs

Check our collection of PDFs for more research documents about coenobita and sea shells.

References:
1. Wilde, 1973
2. Abrams 1978