Hermit crabs can be a range of colors, usually bright and vibrant. It’s likely the color and shade of hermit crabs initially caught your eye. However, it’s concerning if your hermit crabs seem to be changing color.
Hermit crabs start to fade in color, usually to an ashen gray, ahead of molting. Poor nutrition and excessive light can bleach the color of hermit crabs. Dark, black spots can point to a bacterial infection or decomposition. Bright colors denote good health but could relate to a stained substrate or decorated shell.
Color changes in hermit crabs always have a reason. How concerning this is depends on the color change. Happy, healthy hermit crabs have bright, eye-catching coloring. If this changes, then you need to find out why.
What Color Should a Hermit Crab Be?
One of the reasons that hermit crabs are so visually striking is their coloring. There is no single, universal color for hermit crabs. Different species have different markings. Sometimes, this is reflected in the name of the hermit crab. Examples of this include:
- Paguristes cadenati – red or scarlet reef hermit crab
- Coenobita purpureu – blueberry hermit crab
- Coenobita clypeatus – Purple Pincher (or Caribbean hermit crab)
These names, while colloquial, give you a good idea of what color your hermit crab should be. Your hermit crab may have a more generic moniker, though. For example, a popular pet breed in the USA is the Coenobita compressus, aka Ecuadoran hermit crab.
This means that there is not one color that a hermit crab ‘should’ be. If your hermit crabs are changing color, there is likely a reason for it.
What Color is a Healthy Hermit Crab?
Hermit crabs will be a deep and vibrant color. The exoskeleton of a hermit crab is white, but this should be covered by bright and brilliant flesh. The paler a hermit crab looks, the likelier they are to be unhealthy.
This does not automatically mean that a pale hermit crab is sick or dying. As we will discuss shortly, natural actions such as molting lead to hermit crab colors fading. Your hermies will regain their traditional coloring when the molt is complete.
All the same, healthy hermit crabs should enjoy deep coloring, whatever their natural hue may be. Avoid purchasing hermit crabs that are gray, white, or otherwise washed out. They are scheduled to molt or are sick. Either way, the stress of relocating into captivity will likely kill them.
Should Hermit Crabs be One, Uniform Color?
Many hermit crabs have varying colors and shades throughout their body parts. The Caribbean hermit crab is known as the Purple Pincher as its claw is deep purple, while the rest of the body is typically red.
The legs of a hermit crab may also differ from the abdomen. Clibanarius tricolor, for example, is a popular pet marine hermit crab. This is known as the blue leg hermit crab, for obvious reasons when you see one. The claws and body are usually black, though.
The legs of any hermit crab typically vary in color. Sometimes this is natural, and sometimes it’s a sign that something is amiss. Legs turning white, for example, are early suggestions that hermit crabs are preparing to molt or nursing an injury or illness.
My Hermit Crab is Losing Color
Your first step should be to observe your hermit crabs. Are they eating and drinking as normal? Are the hermit crabs active and playful after dark or growing lethargic? Are all the hermit crabs changing color, or just one?
If multiple hermit crabs are losing color, it suggests that something is amiss in the habitat. Check the temperature and hygrometer. Most hermit crab owners follow the 80/80 rule – 80% humidity and a temperature of 80 degrees – to mimic a natural environment.
This is not an exact science, though. Some hermit crabs are more comfortable in cooler climes. Learn the warning signs that hermit crabs are overheating. If so, reduce the temperature a little. The fading color may be due to environmental stress impacting health.
If humidity is below 80%, increase it at once. Hermit crabs suffocate in low-humidity environments. If this is not a concern, ensure the hermit crabs are not experiencing toxicity. Paint flecks from decorated shells or the use of tap water are the likeliest culprits here.
Look into how much light is reaching your hermit crab tank. Wild hermit crabs are sometimes bleached gray by the sun. If this is happening to your hermies, reduce the intensity of light in the room. Hermit crabs are sensitive to excessive illumination.
Do Hermit Crabs Change Color When They Molt?
The most common reason for hermit crabs to fade in color is an impending molt. As per the Journal of Experimental Marine Biology and Ecology, hermit crabs molt several times in the first three years of their life. They increase in size and mass each time.
Molting is an intensely private experience for hermit crabs. This is why removing a verb from a shared habitat once it starts to fade in color is advisable. This is the first sign of molting. The hermit crab’s skin will fade to a dull, ashen gray, Other signs include:
- Eating and drinking more than usual (storing fat and water)
- Glassy, glazed expression in the eyes
- Uncharacteristic lack of energy and general lethargy
- Digging more than usual, as though making a tunnel
Once the hermit crab is ready to molt, it will retreat beneath the substrate. It will likely stay here for several weeks, or even months. Leave your hermit crab alone during this time. Molting hermit crabs must not be disturbed.
When the molt is complete, the hermit crab will re-emerge from the substrate. At this point, the skin will be restored to its former, brilliant vibrancy. Once molting hermit crabs have acquired a new shell, they can rejoin their erstwhile tankmates.
Does Diet Influence Hermit Crab Color?
Hermit crabs need to be fed an appropriate diet to stay healthy. If your hermit crabs are looking washed out, ensure they are eating enough and correctly. Hermit crabs need large quantities of protein and calcium.
Another critical element of the diet of hermit crabs is beta-carotene. This is an antioxidant found in fresh fruits and vegetables. Carrots are the best source of beta-carotene for your hermit crabs.
Marine Biology confirms that the presence of beta-carotene and other carotenoids is linked directly to skin pigmentation in hermit crabs. Essentially, the more carotenoids your hermit crabs consume, the deeper and brighter their coloring will be.
This suggests that hermit crabs fading in color could be due to dietary deficiencies. Watch the eating habits of your hermit crabs and ensure they are not ignoring essential nutrients. If this is the case, make critical foodstuffs more appealing to your pets to restore coloring.
Do Hermit Crabs Change Color When They Die?
Humans and mammals frequently display key signs of aging. One of the most common is the graying of hair (or fur in animals). This is due to the steady reduction of melanin in hair follicles.
This does not apply to hermit crabs, so they should not fade in color as a natural aging process. Unfortunately, this means that a gray hermit crab may be dead. Hermit crabs are delicate and can die suddenly and without warning.
Unfortunately, dead hermit crabs look, behave and smell similar to molting crabs. In both instances, the skin will fade to a dull gray. Molting means that one exoskeleton is dying, and a new one replaces it.
This means that you’ll need to be patient with a gray, unmoving hermit crab. There is every chance that the crab is not dead, just undergoing a rebirth. Do not immediately assume that hermit crabs that have lost color have died.
Do Hermit Crabs Change Color as Camouflage?
Some animals display chameleonic abilities, changing body color and shade to blend in with their environment. This is a defense mechanism to hide from predators. Hermit crabs are at the bottom of the wild food chain and would benefit from this skill.
Unfortunately, hermit crabs cannot change their body color. Instead, as per the Journal of Experimental Biology, hermit crabs choose shells that blend into the background. Even then, hermit crabs typically choose shells with a clear contrast as they are easier to see.
This means that your hermit crabs are not changing color or fading due to fear of predation. On the one hand, this is a good thing. Your hermit crabs are not stressed due to concerns over their safety. It does suggest that something else is wrong, though.
Changing Colors in Hermit Crabs
If your hermit crab’s skin is turning red, that’s usually a good thing. Red is a default skin shade for many hermit crabs. The deeper and darker the hue, the healthier the hermit crab theoretically is. It’s the opposite effect that you need to worry about.
If your hermit crab is not red, switch this color for an appropriate alternative. A hermit crab turning blue is fine in breeds that enjoy this striking coloration. Equally, the dominant claw of our old friend, the Caribbean hermit crab should start turning purple after molting.
The one exception to this comes when hermit crabs are trapped in their shells. This suggests that the changing color is caused by running paint applied to a decorated shell, gluing the crab within, and staining the skin. This is one of many reasons why painted shells should be avoided.
Hermit Crabs Turning Pale
As we have mentioned previously, hermit crabs losing all pigmentation and turning pale requires action. Any hermit crab that is paling should be placed in isolation. You’ll need to assess the cause of this issue.
Hermit crabs turning gray is quite common and is not necessarily irredeemable. It could be something as commonplace or innocuous as molting. It may be a warning sign that the hermit crab is sick, but it could still be nursed back to health.
Hermit crabs turning pure white is more concerning and rarely ends well. Essentially, if your hermit crab is bright white, it means you are seeing its exoskeleton. That is never a good thing.
To recap, the most common reasons for hermit crabs to fade to gray include:
- Preparing to molt
- Bleaching from excessive light in the habitat
- Failing to gain appropriate nutrition from diet
There could still be a problem with the habitat, especially if multiple hermit crabs are graying simultaneously. This is not a healthy color. Do not disregard this change as a natural process. Isolate gray hermit crabs and identify the cause of their color change.
If your hermit crab is turning pure white, you need to start preparing yourself for the worst. If a human were deathly pale, you would be concerned. The same level of worry needs to be applied to hermit crabs without a hint of color on their skin.
If other hermit crabs gather around a white tankmate, the crab in question is likely already dead. As per Ecology and Evolution, dying hermit crabs release specific pheromones. Conspecifics pick these up.
Your other hermit crabs are amassing for two reasons. They want to try on the now-vacant shell left by the deceased, and they may eat the carcass. Hermit crabs are natural scavengers. They are not above cannibalism.
To be safe, remove a white hermit crab from a shared enclosure. Even if still alive, it is unlikely to remain this way for much longer. Until you know what killed it, it should be kept away from the rest of your hermies. The cause of death could be contagious.
We are referring to hermit crabs turning pure white all over. If you notice white spots, it’s serious but unlikely to be life-threatening. Look closer, and you’ll likely notice that your hermit crab has mites. This still needs to be dealt with, but your hermit crab will survive.
Hermit Crabs Becoming Darker
Hermit crabs growing darker in color may be a warning sign of a bacterial infection. Alternatively, it could just be the staining that we previously warned of. All paint should be avoided on shells, but dark paint is especially inadvisable.
All the same, dark spots and patches on hermit crab skin are rarely good. Your first action should always be to place your pets in a saltwater bath.
Black spots on a hermit crab should be considered an emergency. Place your hermit crab straight into a saltwater bath. If the black does not wash off, this is likely a bacterial infection.
These infections can be fatal to hermit crabs. Isolate the impacted pet at once, ensuring the new habitat is clean. Also, rehome all tank mates. The habitat must undergo a thorough deep clean. The bacteria will only spread and harm more hermit crabs otherwise.
If the scent of rotten fish accompanies black spots, the skin is decomposing. The best you can hope for is a peaceful passing before the hermit crab experiences more pain. Euthanasia may be the most humane decision.
There is no good reason for hermit crabs to turn brown. This means that the likeliest explanation is staining. This could be coming from the substrate or excrement.
The latter is less likely but possible. Hermit crabs do eliminate, but they’re typically quite fastidious. Hermit crabs poop within their shells, then flick the waste onto the substrate once it builds up. If you are on top of your spot cleaning, it should not stain the skin.
Some hermies like dirt and soil, though. If you include these in your substrate, your hermit crabs likely rolled around in them. The same applies if you use plant pots as toys in a habitat. Soil can stubbornly cling to hermit crabs and must be washed off.
Hermit crabs change color for various reasons, and it is never just “one of those things.” Pay attention if your hermit crab looks different. If this is paired with a shift in behavior, something is almost certainly up.