How Often Do Hermit Crabs Change Shells?

As a pet hermit crab owner, you may notice your crabs changing shells frequently. This can seem confusing, as hermit crabs appear very attached to their mobile homes. So why do hermit crabs swap shells, and how often does this behavior occur?

I’ve owned hermit crabs for years and have done extensive research to satisfy my own curiosity about their shell changing habits. Here I’ll share everything I’ve learned about the frequency of shell changes and the reasons behind this important part of a hermit crab’s life.

An Overview of Hermit Crab Shell Changing

Hermit crabs outgrow their shells as they grow larger through molting. They also like to upgrade to newer, better fitting shells whenever possible. For these reasons, most hermit crabs change shells:

• Before or after molting
• When finding a more preferred shell
• At least twice per year

The frequency of shell changes depends on the individual crab’s growth rate, species, and the availability of empty shells in its environment. Let’s look closer at the factors that influence shell swapping.

Shell Changes Related to Molting

Hermit crabs shed their exoskeletons periodically in a process called molting. Prior to molting, a crab may switch to a smaller shell to fit their temporarily smaller body size post-molt.

Then, after their new exoskeleton hardens, they’ll seek a larger shell to accommodate their grown body This often prompts a shell change.

On average, hermit crabs molt every 12-18 months. So you can expect them to change shells in preparation for molting or to size up after molting around this frequency.

Shell Changing and Species Variations

Some hermit crab species change shells more readily than others, For example

• Caribbean hermit crabs, or purple pinchers, are very active shell changers. They swap shells on a whim whenever they find one they like better.

• Ecuadorian hermit crabs are much pickier. They’ll only swap shells when they really need to due to molting or damage.

So depending on your particular crab’s species, its shell changing habits may differ. A purple pincher will likely change more frequently than an Ecuadorian crab.

Availability of Empty Shells

The number of empty shells available also impacts shell changing frequency. When options are limited, a crab will retain its current shell longer. But when given abundant larger shells, they are likely to size up at each molt.

As a general rule, you should provide 3-5 properly fitting shell options per crab. This allows them to upgrade shells without delay when needed.

Signs Your Crab Needs a New Shell

How can you tell if your hermit crab is ready for a new home? Here are a few signs:

• It cannot fully retract into its shell
• The shell is chipped or damaged
• Your crab is sluggish and inactive
• Its growing body is cramped inside

If you spot these clues, add some larger shells to give your crab options for upgrading.

Encouraging Your Crab to Change Shells

While you can’t force a swap, you can provide an environment conducive to smooth shell changing:

• Offer 3-5 clean, empty shells of the appropriate shape/size
• Include 1 slightly larger and 1 slightly smaller shell
• Maintain proper heat, humidity, and extra shells at all times
• Give new shells a “test run” period to avoid rapid swapping

With the right habitat and shells available, your crabs can safely change shells on their own terms.

The Shell Changing Process

When a hermit crab decides its time for a new mobile abode, here is what the shell changing process entails:

1. The crab will inspect and climb into a new shell it finds acceptable.

2. It remains in the new shell for a trial period before fully evacuating its old shell.

3. When ready, the crab retracts into the new shell then exits completely, leaving the old shell behind.

4. It may also opt to change back to its old shell if not satisfied with the new one during the trial run.

5. Once content in its new home, the shell swap is complete!

Possible Reasons for Frequent Shell Swapping

While some shell changing is normal, what if your crab seems obsessive about constantly swapping shells? Frequent changes may be due to:

• Inadequate humidity causing discomfort
  -drastic temperature fluctuations
  -lack of proper fitting shells
  -irritation from dirt, mites, or bacteria
  -general stress in the environment

If your hermit crab is rapidly changing shells, assess its habitat for issues and remedy any problems found.

Shell Changing Safety Tips

To make each shell change smooth and safe for your crab, keep these tips in mind:

• Never pull a crab forcibly from its shell – this can injure them
• Avoid painted shells as the paint may chip and be toxic
• Clean empty shells thoroughly before adding them
• Give adequate transition time between shell swaps
• Monitor for signs of stress like hiding or inactivity after changing