How Can You Tell if Your Hermit Crab is Molting?

Molting is a natural process that all hermit crabs go through as they grow. During a molt, the hermit crab sheds its rigid exoskeleton to make room for new growth This process allows the crab to grow larger and regrow any lost limbs While molting is perfectly normal, it can sometimes be hard to tell if your hermit crab is molting or if something is wrong. This guide will walk you through what to look for to determine if your crab is molting.

What Does Molting Look Like?

When a hermit crab starts molting its entire body will go limp and it will stop moving altogether. Often, part of the crab’s body will hang outside of the shell. The crab loses control of its muscles during this time so any leg or claw movements will cease. A molting crab may also have a milky, opaque cast to its shell and eyes.

While the crab is molting, you likely won’t see any signs of life. A molting crab will appear quite limp and lifeless, and the body is often partway out of the shell.1 Sometimes, with very careful observation, you will be able to see small twitches from the hermit crab’s body while it is molting, but otherwise, it can be very difficult to tell whether or not it is still alive.

The molting process can take several days to several weeks depending on the size of the crab. Smaller, younger crabs molt more frequently and can molt in just a couple of days. Older, larger crabs may take a few weeks to complete the process.

Signs That Molting is About to Begin

Luckily, there are some clues that can tip you off that a molt is about to happen. Watch for these signs:

Increased appetite. In the days leading up to a molt, a crab may start eating more than usual to store up energy.
Lethargy. An impending molt may cause a crab to become more inactive and hide away in its shell.
Abdominal bubbling. You may see a dark bubble appearing on the left side of the crab’s abdomen as it stores liquid before molting.
Milky eyes. A crab’s eyes will take on a milky, opaque color right before molting.
Limb buds. If your crab previously lost a leg, a tiny limb bud may appear where the leg fell off as the crab prepares to regrow it.
Adding shell weight. Some crabs may line the opening of their shell with substrate or algae to make it heavier and hold them in place during a molt.
Shell switching. Your crab may switch into a larger shell in anticipation of its growth.
Digging. Crabs may dig pits in the substrate where they can safely molt underground.
Color loss. The vivid colors on a crab’s legs and claws will fade as the molt approaches.

Behaviors to Expect During Molting

Once the molt starts, you will notice some specific behaviors:

The crab will stop moving and eating. All signs of life will cease.
The crab will hang limply in or out of its shell. Much of its body may dangle from the shell’s opening.
The eyes will be milky and opaque. They will lack their usual color.
The body may twitch subtly. Observant owners may notice slight twitches.
A foul odor is possible. A distinct musky or fishy smell may emanate from the shell.
The crab may come partway out of its shell. Up to half of its body may hand outside the shell.

Caring for a Molting Crab

The most important thing you can do for a molting crab is leave it completely alone. Don’t touch it, poke at it, or otherwise disturb it during this vulnerable time. Just maintain proper humidity and temperature in the tank and resist the urge to interfere. Offering food is pointless since the crab cannot eat or move until the molt is over.

Here are a few tips for caring for a molting crab:

Keep the tank humid using a humidifier or moist substrate. This will help ensure proper shell hardening.
Maintain a warm temperature around 75-80°F. Warmth speeds the molting process.
Don’t touch or handle the crab at all. Even a gentle poke can injure it.
Don’t attempt to remove the crab from its shell. This can severely harm the crab.
Avoid tank cleaning and redecorating during a molt.
Monitor humidity and temp levels carefully each day.
Resist the urge to assist the crab. Molting is a natural process that doesn’t require help.

Signs that Molting is Over

Once your crab has successfully molted, you will see some clear signs that the process is complete:

It will regain movement in its legs and claws.
Its eyes will become vividly colored again.
It will become active and eager to eat again.
Any lost limbs will have been replaced.
Its body will fit better into its shell with room to continue growing.
Its coloration will become more vibrant.
It will spend less time hiding and more time roaming around.

When to Worry

In most cases, molting goes off without a hitch. But occasionally, you may encounter issues like:

The crab dies during its molt. This usually only happens if tank conditions were unsuitable.
The crab becomes stuck in its old shell. High humidity can help loosen the shell. Avoid pulling on the crab.
No new growth occurs. Lack of proper nutrition can prevent growth. Review diet and supplement.
The crab loses limbs. Proper calcium intake helps prevent limb loss.
The crab becomes lethargic after molting. This may indicate inadequate heat levels in the tank.
The new shell doesn’t harden. Low humidity levels likely prevented shell hardening. Boost humidity.

If you notice any of these issues, review your hermit crab care regimen and tank setup to determine if improvements need to be made before the next molt. You may need to tweak heat, humidity, diet, or other factors.

Molting can sometimes look like a lifeless crab, but it is actually a vital process for a hermit crab’s growth and development. By knowing what behaviors to expect before, during, and after molting, you will be able to provide the best care for your crab. Pay close attention in the days leading up to a molt and resist the urge to interfere during the process. With proper preparation and care, your crab can molt smoothly and return to normal activity once its new exoskeleton has hardened. Molting is a complicated process but it does not require any intervention on your part. Just let nature run its course and your crab will be back on its feet in no time!

how can you tell if a hermit crab is molting

Is My Hermit Crab Dead or Molting?

FAQ

How do I know if my hermit crab is going to molt?

As molting time approaches, the crab’s gel limb will expand and become more defined. Legs and claws may seem droopy or weak. Eye stalks may face away from each other in a “V” shape rather than being parallel. They may also appear cloudy, white-ish, and dull, like a human’s cataract.

What does a hermit crab look like before it molts?

Other visual signs: a crab that needs to molt will often times have dull looking cloudy eyes and a chalky appearance to their exoskeleton. Also, crabs that have lost an appendage will have a pronounced “limb bud” just prior to molting.

What color do hermit crabs turn when they molt?

Color Changes Due to Molting His overall coloring might seem a lot less vivid than before, and it could look sort of gray and ashy, particularly on the ends of the legs and around the joints. You also might notice some light beige elements on parts of your hermit crab’s physique, particularly around the chelipeds.

Do hermit crabs molt?

Hermit crabs are prone to periods of solitude and lethargy, particularly when they’re molting. It can be difficult to tell whether a hermit crab is molting, sick, or dead. As a general rule, though: assume molting before death, unless you have evidence to the contrary. Read on for tips about diagnosing and caring for your hermit crab!

How do you know if a hermit crab is dead?

Sniff around for a fishy, rotten smell. This is the surest way to identify a dead hermit crab. If your hermit crab dies, it will begin to decompose – and its carcass will begin to smell putrid. If you can’t smell anything, pick the crab out of the tank to get a closer whiff.

How do I know if my crab is molting?

A healthy crab that is suddenly digging more than usual is a sign that molting is approaching. However, first check your thermometer and humidity gauge. If a tank is too warm, cold, or dry, your crab could be trying to dig a new habitat underneath the sand to get away from unwelcome conditions.