Tag Archive for hermit crab

Land Hermit Crab Shell Guide

Wee wants to be big so bad

Wee wants to be big so bad

A hermit crab’s shell is his home and his protection from predators and desiccation. 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. Provide 3-5 suitable shells per hermit crab. Shells can be placed directly on the substrate or in a designated bin that we call a Shell Shop. This helps keep the shells clean and reduces the chances of them being buried.

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. Coenobita violascens prefers a long spiral type shell.

Shells should be cleaned and boiled in Prime treated water before offering to your hermit crabs. Many owners also do a final rinse in ocean water before placing in the crabitat but this is not required.

***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.

How to measure the opening of the shell.

My shell is too small!

My shell is too small!

Coenobita cheliped pincer claw

My shell fits just right!

Shape – Round Opening

Shape – D Opening

Good shells preferred by C. violascens

C. violascens enjoy long spire type shells.

Unsuitable Shells

Good but usually ignored

When and why do hermit crabs change shells?

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.

The Social Lives of Hermit Crabs


Sara Lewis and Randi Rotjan, New England Aquarium and Tufts University: Hermit Crab Vacancy Chains:

From BBC One: Hermit Crab Housing:

Photos of Coenobita Cavipes lining up for a shell change in Singapore

1. Wilde, 1973
2. Abrams 1978

Correction: Feeding Guide

Please be advised that there is an error on the printable feeding guide. The version on the website has been updated. Please update your copy. REMOVE CANOLA OIL.  Canola oil is not safe.  We apologize for the error.

Airborne Irritants and Hermit Crabs

Hermit crab's gills are sensitive to airborne irritants

Hermit crab’s gills are sensitive to airborne irritants

Land hermit crabs breathe through a modified gill. It is important to protect the gills from strong fragrances, essential oils, candles, household cleaners, chemicals, smoke insecticides and other airborne irritants.

Be mindful of what you spray or use near the crabitat even if your tank is fully sealed. Residual product may still be in the air when you open your tank.

If you are forced to have your home sprayed for insects ensure your tank is fully sealed with saran wrap or something similar. Allow the house to air out at least 24 hours before unsealing your tank.

Humane euthanasia for hermit crabs



There may come a time when you find it necessary to euthanize your hermit crab to end it’s suffering. I’m providing the information that I found to be reliable.

Please ensure that you are not confusing a surface molt with death.



Say NO to Painted Shells Coloring Pages

Click the image to be taken to the full size image then right click to save to your computer.

Hand Drawn by Judy Christopher for CSJ

Hand Drawn by Judy Christopher for CSJ

Hand Drawn by Judy Christopher for CSJ

Hand Drawn by Judy Christopher for CSJ

FAQ-Are there other pets that can live with hermit crabs?

In 2009 we introduced isopods to our crabitats.

In 2009 we introduced isopods to our crabitats.

The list of critters that can safely exist with hermit crabs is fairly short.


Isopods – beneficial tank cleaners
Springtails – beneficial tank cleaners
Food/soil mites – harmless


Fiddler Crabs/Halloween Crabs – aggressive diggers and are likely to eat molting hermit crabs.

Fiddler and Halloween crabs are aggressive diggers

Earth worms, beetles, centipedes, crickets, praying mantis, roaches: May stress each other, over populate, disrupt/harm/ kill/ eat molters. Crabs may harm /kill them. May carry/spread disease/parasites, especially with over population.

Centipedes – venomous
Millipedes – poisonous 

Snails – Hermit crabs can kill snails

Frogs/Lizards – could harm each other, different habitat needs

Fish – inappropriate water for a fish

Updated method for treating water with Prime

Prime Water Conditioner

A member of HCO on FB (not affiliated with LHCOS/CSJ) raised an issue regarding the use of Prime.

After doing some research of our own we are in agreement with their conclusion regarding Prime treated water and pre-mixing.

Please note: As we do not have the necessary information to determine how land hermit crabs are affected by ammonia build up in the water and to what degree we err on the side of caution and treat our water as we would for fish. All information regarding Prime is based on the assumption it is being used in a stable fish tank. Our use is much different. Our primary reason for using Prime is to remove Chlorine and Chloramines and heavy metals from the water and Prime does that well with no recurrence that requires retreatment.

Ammonia build up is only an issue when using semi permanent deep water pools.

You can refer to this link for more information (specifically the comments made by the Seachem staff):


Who does this affect:

Anyone who premixes water with Prime and stores it for later use

Who this does not affect:

Anyone who treats with Prime at the time of a water change

How do I correctly use Prime:

Standing water dishes/pools:

Change the water entirely every two days. Treat with Prime right in the dish or pool if you wish, swish gently to mix.

Bubbler enhanced dishes/pools:

Change the water entirely twice a week. Add Prime when adding new water.

Filtered semi permanent pools:

  • Partial water changes every two weeks and retreat the pool. Change ¼ of the water.
  • Top off the pools as needed and retreat (unless you have a proper ammonia test kit).
  • Don’t scrub your filters and parts squeaky clean, keep the good bio stuff.
  • Do rinse everything off with Prime treated water.

To correctly test your water for ammonia build up you will need a good quality test kits. Cheaper kits will not work with Prime and will always read toxic.

Seachem Ammonia Alert: http://amzn.to/2EjmfcX

Anthocyanin Nibbles

Anthocyanin nibbles

Anthocyanin nibbles


1 portion dark red/black cherries
1 portion blackberries
1 portion blueberries
1 portion red apple (Unwaxed only, she peel is the important part)
1 portion red beets
1/2 portion red raisins
1/2 portion dried plums/prunes
2 portions red beans (do not skip, or you won’t be able to grind into a powder)

Blanch each item in a small pot of crab safe water, reserving and reusing the water for each item. Prunes and raisins get soaked in the warm water last until they are very soft. Blend all items, including the reserved soaking/blanching water (start with a little) until its a paste about as thick as pancake batter. You may feed it to them fresh like this and freeze it in portions, or continue on to drying and powdering. To dry, line your dehydrater trays with silicone inserts, or parchment paper cut to size. Do not use wax paper, it will melt into the food 😝. Spread it across each sheet evenly about 1/3 inch thick, or less. Dry at about 130°f for a minimum of 24 hours, can take a couple of days. It depends on how thick it is and how humid your environment is. To test if it’s done, let it cool through. If you can break it into pieces, it’s ready. If it only bends and will not break, dehydrate longer until it breaks. Whiz it up in the coffee/spice grinder you keep for the crabbies, no cross contamination please 🙂 Store in an airtight glass jar in a cool dark space.

Submitted by Amber Miner

Coenobita respiration


A hermit crab’s gills are enclosed in the branchial chamber, which functions as a lung. The branchial chamber is on the sides of the thorax, above the crab’s legs. A hermit crab breathes through its gills and branchial chamber, which must be kept moist in order to function. If the branchial chamber and gills dry out, the crab will die. Compared to aquatic crabs, land hermit crab’s gills are reduced in size, and if the adults are kept underwater too long, they will drown. [2]

There are tufts of setae at various sites on the ventral surface that enable moisture from the substrate to be passed to the branchial chamber. [1]

Maintaining the correct relative humidity inside the crabitat is crucial to survival. Without sufficiently humid air your hermit crabs will slowly suffocate and die. Once the gills are damaged from too dry air they can not repair themselves.

Unless you live in a native climate and do not use any form of heat or air conditioning your crabitat will require a lid to maintain the correct humidity levels. Your house is likely 40-50% relative humidity.

A hermit crab requires 70-80% relative humidity. This range is for the purple pincher hermit crab (Coenobita clypeatus) native to Florida and the Caribbean. Other species of land hermit crabs enjoy a slightly higher relative humidity of 85%. You will need a solid lid for the crabitat (tank or aquarium) and a good quality hygrometer and thermometer to accurately measure the air inside of the crabitat.

All hygrometers should be calibrated prior to use.

Different ways to create humidity in your hermit crab habitat.

This tank is set up correctly with solid glass lids.

Humidity levels maintained above 85% are not harmful to the hermit crab directly but can lead to an unsafe environment in the crabitat. Floods, excessive surface mold and mildew, slime mold and bacterial blooms are just of the unsafe conditions that can develop from maintaining excess humidity levels.

Treat your hermit crab in the same manner you would treat a fish and refrain from removing them from their humid environment unless absolutely necessary. A very brief photo from time to time is acceptable. Taking your hermit crab from the tank on a regular basis (for any purpose) is strongly discouraged.

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1. Biology of the Land Crabs Warren W. Burggren and Brain R. McMahon
2. Hermit crabs : everything about anatomy, ecology, purchasing, feeding, housing, behavior, and illness Sue Fox

Central Heating and Air Conditioning