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Choosing Hermit Crab Shells

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Finatics enjoys writing about animal care and is "owned" by a guinea pig, four hermit crabs, three African dwarf frogs, and a betta fish.

This misguided hermit crab chose a small glass jar as its shell.

This misguided hermit crab chose a small glass jar as its shell.

Hermit crabs have adapted to using other animals' shells that have washed up on shores as a survival strategy. Predators cannot reach the crabs as easily when they withdraw into their shells. These mobile homes have allowed hermit crabs to survive and thrive in a number of marine environments across the globe.

Do hermit crabs change shells when they molt?

It is a common misconception that hermit crabs change shells when they molt. When hermit crabs molt, they can change shells if they want to, but do not need to necessarily.

An array of shell options.

If you own hermit crabs, shells should be chosen with careful attention to their size and shape in order to find the best fit for your crab. Imagine wearing clothes that don’t fit and are too small or too large. Incorrectly sized shells are uncomfortable for them, as well.

Measuring Shells for Sizing

Measuring the opening of the crab’s shell will give you a good idea of the size of shells they need. If you’re trying to order online, some stores will separate shells by sizes, such as ¼’’ to ½’’ openings, to make them easier to select. Providing them with good-quality shells is important as well. Shells with cracks in them are not appropriate since they do not hold moisture well. The crabs will also refuse to use damaged shells.

Different Species' Shell Preferences

The first step is to determine the hermit crab’s species. This is not completely necessary, but certain types of crabs prefer some kinds of shells to others. For example, Ecuadorian crabs are known to prefer shells with D-shaped openings over ones with round openings, as they have wider, flatter thoraxes than Caribbean crabs. They are also known to stick with one shell for a long time, even if it is a bit too small, whereas Caribbean crabs tend to change shells more frequently.

Each hermit crab must be provided with an array of shells so they can switch shells when they need to. When adding shells to the crabitat, remember to look for shells with similar-sized openings and not necessarily similar-sized shells. Hermit crabs can be quite picky about the shells they choose, so be sure to have a variety of them. If you think your crab’s shell is a little big, add some that are a bit smaller. Without a good selection of shells, shell fights are more likely to occur, and this can be fatal to your hermit crabs

Painted shells can be detrimental to your crabs' health.

Painted shells can be detrimental to your crabs' health.

The Dangers of Painted Shells

Shells are not just accessories, they are actually imperative to the crab's survival. Without a shell, a hermit crab becomes food for other animals. Since hermit crabs are forced into a painted shell, they're often not the right size. In addition, sand can scrape off the paint of the shell (which could be toxic) and contaminate the food, water, and even the entire crabitat.

Sometimes, when the crabs are forced into shells that are too small or have wet paint, they can get stuck inside their shell and die slowly of starvation.

Although painted shells look pretty in pet shops, hermit crabs are usually forced into these shells through several types of painful and terrifying experiences, such as:

  • cracking the crab's shell so he is scared out of it and the only other choices for shells are painted
  • attempting to yank the crab out of his shell (only most crabs are ripped in half)
  • drilling a hole in his shell, then poking him until he is scared and frightened out of it
  • shoving a hermit crab in the freezer in order to slow him down, then inserting him into the painted shell
  • leaving food on one side of the tank, then blocking the crab from reaching it unless he leaves his shell. Once he does, his shell will be replaced with a painted one

Painted shells are cruel and dangerous, and the manner in which hermit crabs are forced into them is even worse. Not only are they harmful and potentially disastrous, but painted shells can also look just plain ugly and even tacky. Natural shells can be beautiful as well as realistic and are a much better selection.

When shell-hunting, please do not buy painted shells and make a good choice for you and your crabs. Your crabs will live happier, healthier lives, and you won't have to spend as much money.

Shells that are fully intact are preferable to those with cracks.

Shells that are fully intact are preferable to those with cracks.

Additional Source for Shell Sizing:

With so many great natural shells to choose from, there is no need to resort to fake or painted ones.

With so many great natural shells to choose from, there is no need to resort to fake or painted ones.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


finatics (author) on June 21, 2012:

@brittany, sorry I don't live in NY, so I can't help you there! However, there are many sites that you can order off of for a relatively low price, such as this one:

finatics (author) on June 02, 2012:

@deadman forever, yes, it's good that you are no longer supporting that cruel industry, but please be sure that the paint on the shells do not contain toxins that will harm your hermit crabs.

brittany on May 29, 2012:

well i just got a hermit crab (his name is resse) i got him at hershy park in pa and he looked cramped and he was in a small wire cage with like 35 other crabs and i don't know where in ny i can get more (natrual) shells i can get him

deadman forever on February 25, 2012:

i have hermit crabs in dirt and painted shells and they all have been around forever but i do no that it is crull how people force theme in painted shells so i just by painted shell and they move in there fast

finatics (author) on November 21, 2011:

Great job on taking good care of your pets!

Doesn't matter what my name is, just read my comment on November 13, 2011:

I hate pet shops and board walks. i got my crabs at a pet shop, but they were a few of the only ones there. the tank was just wire, it didn't have any sand or dirt for them to dig in, and there were no natural shells. this christmas, im hoping to get and even bigger tank and to get a colony of crabs. :D love my little buddies!!!

finatics (author) on June 26, 2011:

Thank you, bella sanchez. Are you sure your shell isn't painted? Painted shells are unhealthy, and I recommend you buy your hermit crabs a few natural shells to live in if they choose.

bella sanchez on June 19, 2011:

i love hernmit crabs i let mine walk all over my house my mom says their weard my hermit crabs shell is so cool it is zebra pink and lime green they hav lived 10 years and there huge

finatics (author) on March 26, 2011:

Glad you like keeping hermit crabs, Rebecca! They are really great animals, and you seem to be taking good care of them. Yours might even live to be over 20 years old!

Rebecca on March 25, 2011:

we have hermit crabs. we have them in a crabitat and they are doing great. they get funtime in the bathtub with water and get to crawl around. they love crawling up and down our arms. they are great pets and mine have been alive for over a year. you need to read up on them and follow the directions for their care. i plan on getting another habitat for crabs.

finatics (author) on August 27, 2010:

Thanks for the comment. I agree with you that hermit crabs are not usually kept in good care at the pet stores and most people that own hermit crabs probably have no business doing so. I like keeping them as pets myself though, but when all of the hermit crabs are taken from the wild, their numbers steadily decrease. Especially when people have no idea how to care for them and they quickly die. If people could take care of them, I would feel more comfortable keeping them as pets.

Holle Abee from Georgia on August 23, 2010:

I don't like the idea of people keeping these as pets. Most of the ones I've seenin stores live in such crowded conditions that they don't even have room to walk.

You bring up some excellent points! Rated up!