Hermit crabs go through several steps during the molting process. These include getting ready for the molt, shedding the exoskeleton, hardening the exoskeleton, and the recovery period. Although the shedding of the old skeleton doesn’t take long, the stages that come before and after it often do. These are also the most stressful and important stages.
Molting is a crucial part of a hermit crab’s life. As pet owners, it’s important we understand the molting process so we can help our crabs through this vulnerable time. In this article, I’ll explain everything you need to know about hermit crab molting.
What is Molting?
Molting is the process by which a hermit crab sheds its rigid exoskeleton The exoskeleton is the hard, outer shell that protects the crab’s soft body This shell doesn’t grow with the crab, so in order for the crab to grow, it must periodically shed the exoskeleton and grow a larger replacement.
Molting allows the crab to increase in size, repair any damage to its exoskeleton, and replace lost limbs or antennae. It’s a complicated process that involves many changes within the crab’s body. Molting is vital to a crab’s health and survival. Without the ability to molt, crabs would not be able to grow at all.
Why Do Hermit Crabs Molt?
Hermit crabs molt for a few key reasons:
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To grow in size: The rigid exoskeleton cannot grow along with the crab. The only way for the crab to get bigger is to shed the current exoskeleton and replace it with a larger one.
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To repair damage If the exoskeleton becomes damaged molting allows the crab to grow a brand new shell. This replaces any cracked or worn areas.
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To regenerate lost limbs Molting gives the crab a chance to regrow any lost or damaged limbs claws or antennae. The new exoskeleton will include all newly regenerated body parts.
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To breed: Female crabs must molt before they can mate and produce eggs. Molting is crucial to crab reproduction.
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To survive: Without the ability to molt, crabs would be unable to grow, repair damage, or breed. Molting is essential to a crab’s overall health and survival.
What Happens During Molting?
The molting process has several stages:
Pre-molt
Pre-molt can take weeks or even months. During this time, the crab’s body starts preparing for the actual molt:
- Stops eating to conserve energy
- Becomes more inactive
- Starts absorbing extra water to expand its body
- A new soft exoskeleton forms under the old one
Molting
This is when the actual shedding occurs:
- The crab finds a safe burrow in deep substrate
- It sheds the hard outer exoskeleton
- The soft new exoskeleton is exposed
- This stage may take 1-2 days
Post-molt
Now the new exoskeleton must harden and the crab recovers:
- The crab eats the old exoskeleton to regain nutrients
- It remains hidden while the new shell hardens
- This hardening process can take weeks or months
- The crab slowly becomes more active as the shell hardens
The whole process lasts several weeks at minimum, and up to several months for larger crabs.
Molting Stages in Detail
Let’s look at each molting stage more closely.
Pre-molt
Pre-molt is when the crab’s body prepares for the upcoming shed. Changes you may notice include:
- Lethargy and decreased activity
- Loss of appetite
- Increased digging or hiding
- Unusual coloration – the exoskeleton may appear discolored or dull
- Milky-colored drainage from joints as fluid builds up beneath the old exoskeleton
During pre-molt, the crab starts absorbing a lot of water. This causes its tissue to swell, which begins separating the old exoskeleton from the underlying skin.
Pre-molt can take anywhere from a few weeks to a few months. Your crab may spend more time burrowing and hiding as its body goes through these changes. Be sure to provide deep substrate and plenty of hides during this time.
Molting
Once pre-molt is complete, it’s time for the actual shedding process. Here’s what happens:
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The crab will find a secluded burrow in deep substrate to safely molt in private.
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Hormonal changes cause the old exoskeleton to detach completely from the underlying skin.
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The crab extracts itself from the old shell by contracting and contorting its body.
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Once free of the old exoskeleton, the crab is extremely soft and vulnerable. Its body rapidly absorbs water to expand the new soft shell.
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Over 1-2 days, the new shell will harden enough for the crab to cautiously emerge from its burrow.
Molting requires a lot of energy, so the crab will rest quietly in its burrow during this exhausting process. Be sure not to dig up or handle a molting crab! This can damage the fragile new exoskeleton and stress the crab.
Post-molt
After molting, the crab is still recovering and its new exoskeleton is quite soft. At this stage:
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The crab eats some of the shed exoskeleton to regain lost nutrients like calcium.
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It remains hidden while the new shell gradually hardens over the next few weeks or months.
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The crab may drink a lot of water to help expand and harden the new shell.
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As the exoskeleton hardens, the crab slowly becomes more mobile and active again.
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Appetite returns to normal within a couple weeks post-molt.
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Limb regeneration is completed – any lost legs or claws will have fully regenerated by now.
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Shell coloration returns to normal.
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Growth will be maximal in the first few days after molting while the new shell is still pliable.
Be sure to provide shallow water dishes during post-molt so the crab can easily soak and expand its shell. Extra protein and calcium also help harden the new exoskeleton.
The crab will hide while the new shell finishes hardening. This can take several weeks to a few months depending on the crab’s size.
How Often Do Hermit Crabs Molt?
Molting frequency depends on the crab’s age, species, diet, and habitat conditions:
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Younger crabs molt more often than older crabs. Younger crabs may molt every few months as they grow rapidly.
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Older crabs may only molt once a year or less. Growth slows as they age.
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Warmer temperatures, higher humidity, abundant food, and larger shell sizes can all increase molting frequency.
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Ideal conditions allow for faster growth between molts. Colder temperatures or poor diets result in less frequent molting.
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Most pet hermit crabs molt around once every 4-12 months on average.
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Land hermit crabs molt a little more often than marine hermit crabs.
So expect your crab to molt anywhere from every 4 months to once a year. If it’s been longer than a year with no molt, the conditions may need improvement.
How to Care for a Molting Crab
Molting is stressful for hermit crabs. Here’s how you can help your crab through the process:
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Leave it alone – don’t dig it up or handle it.
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Maintain warm, humid conditions between 75-80°F.
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Keep substrate very deep, at least 6 inches.
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Provide ample hiding spots like shells, logs, and plants.
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Ensure proper nutrients with a varied diet.
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Offer extra protein immediately after molting.
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Provide shallow pools for drinking and rehydrating.
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Avoid any tank cleaning/maintenance during pre-molt and post-molt.
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Watch for signs of a problem like unusual odors, lack of appetite, or inactivity lasting over 6 months.
With the proper environment, most crabs molt without any issues. Be patient and allow your crab to complete the molting process fully before handling. Within a few months it will resume normal activity with a larger, healthier exoskeleton!
Molting Difficulties
Molting is risky for hermit crabs. Problems can arise if:
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The substrate is too shallow or lacks humidity.
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They are disturbed/handled during molting.
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The new exoskeleton fails to harden properly.
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An old exoskeleton sticks and won’t shed off.
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Nutrition is poor prior to molting.
Signs of molting trouble include:
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The crab is motionless/inactive for over 6 months
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A foul odor emerges from the burrow
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The crab loses appetite and stops eating/drinking
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The new exoskeleton is soft and rubbery long after molting
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Limb deformities or loss of limbs
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The crab seems unable to fully extract itself from the old exoskeleton
Molting Timetable
The time it takes for a crab to complete a molt varies. As a general rule, the larger the crab, the longer the whole process will take. A typical average-sized crab will go through the whole process in four to eight weeks. During that time, it may stay buried in the sand the whole time. Some crabs, on the other hand, finish the process much faster, while big crabs may need more time.
When a hermit crab molts, it’s best to leave it alone and let nature take its course. It’s hard to not know what’s going on with your crab after it has buried itself. Just look at the crab every once in a while to see how it’s doing. Don’t pick it up or try to help it molt. Hermit crabs have been molting in the wild for a long time, so they know what they’re doing. Also, pulling on its body could do a lot of damage and cause it to lose its limbs.
The Magic of Molting! How to help your hermit crabs molt
FAQ
How do you know if a hermit crab is molting?
How often do pet hermit crabs molt?
What happens when crabs molt?
Do hermit crabs eat each other when molting?
Should you leave a dead hermit crab molt?
Molting times vary from crab to crab, so if your hermit crab is still molting after the expected time, leave it be. It may seem disturbing, but even if your crab has died during the molt, it’s safer to leave the deceased hermit crab for several months, than to attempt to move a crab during its molt.
What is hermit crab molting?
The Mysteries of Hermit Crab Molting: A Comprehensive Guide for Pet Owners. Hermit crab molting is a natural process that all hermit crabs go through as they grow. It’s essentially a shedding of their exoskeleton, which provides support and protection for their body.
How do you know if a hermit crab molts?
Note if your hermit crab is less active. Lethargy and lengthy periods of inactivity are normal leading up to a molt. The molting process is exhausting for your hermit crab, so he will likely rest before and after the process. Look at your hermit crab for signs of molt.
How do hermit crab molts work?
Overall, caring for a pet includes knowing about its biological processes; by taking time now to learn about how a Hermit Crab Molts will allow you greater insight into what’s happening with your pet when faced with this annual event. During the molting process, a hermit crab will first start to absorb water to expand its body size.