Last Updated on September 3, 2023 by Joanne Harper
Hermit crabs have various bright and vibrant shades, but their colors can suddenly change.
Hermit crabs fade in color, usually to an ashen gray, ahead of molting. Also, poor nutrition and excessive light can bleach the color of hermit crabs.
Dark, black spots can point to a bacterial infection or decomposition, while bright colors denote good health but could relate to a stained substrate or decorated shell.
What Color Should a Hermit Crab Be?
One of the reasons that hermit crabs are so visually striking is their coloring.
There’s no universal color for hermit crabs, and different species have different markings. Sometimes, this is reflected in the name of a hermit crab. Examples 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 a hermit crab should be. However, a hermit crab may have a more generic moniker. For example, a popular pet breed in the U.S. is the Coenobita compressus (also known as the Ecuadoran hermit crab).
What Color Is A Healthy Hermit Crab?
Hermit crabs are a deep and vibrant color. The exoskeleton of a hermit crab is white, but this should be covered by bright and colorful skin. The paler a hermit crab looks, the more likely they’re unhealthy.
This doesn’t always mean a pale hermit crab is sick or dying. For example, molting can lead to hermit crab colors fading, but they’ll regain their natural color once the molt has been completed.
However, healthy hermit crabs should have a deep coloring, regardless of their natural hue.
Should Hermit Crabs Be A 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 red.
The legs of hermit crabs may differ from the abdomen. For example, Clibanarius tricolor is a marine hermit crab known as the blue leg hermit crab, but the claws and body are usually black.
The legs of a hermit crab vary in color. This is usually natural but can signify something is amiss. For example, legs turning white indicates that a hermit crab is preparing to molt or nursing an injury/illness.
My Hermit Crab is Losing Color
If multiple hermit crabs lose color, it suggests something is amiss in the habitat.
So, check the temperature and humidity. Most hermit crab owners follow the 80/80 rule – 80% humidity and a temperature of 80 degrees – to mimic their natural environment.
Some hermit crabs are more comfortable in cooler climes, so learn the warning signs that hermit crabs are overheating. If so, reduce the temperature, as the fading color may be due to environmental stress.
If humidity is below 80%, increase it because hermit crabs suffocate in low-humidity environments. If this isn’t a concern, ensure the hermit crabs aren’t experiencing toxicity. For example, the most likely culprits are paint flecks from decorated shells or tap water consumption.
Wild hermit crabs are sometimes bleached gray by the sun. If this is happening to your hermit crabs, reduce the intensity of sunlight in the room.
Do Hermit Crabs Change Color When They Molt?
An impending molt is the most common reason for hermit crabs fading in color.
According to the Journal of Experimental Marine Biology and Ecology, hermit crabs molt several times in the first few years of their life as they increase in size and mass.
The hermit crab’s skin will fade to a dull, ashen gray. Other signs include:
- Eating and drinking more than usual.
- Glassy, glazed expression in the eyes.
- Uncharacteristic lack of energy and lethargy.
- Digging more than usual as though making a tunnel.
Once the hermit crab is ready to molt, it’ll retreat beneath the substrate for several weeks or months. Leave your hermit crab alone during this time, as they mustn’t be disturbed.
The hermit crab will emerge from the substrate when the molt is complete.
Does Diet Influence Hermit Crab Color?
Hermit crabs must be fed a nutritious diet to stay healthy.
If your hermit crabs look washed out, ensure they’re eating enough and the right types of food. Hermit crabs need large quantities of protein and calcium.
Another critical element of hermit crabs’ diet is beta-carotene, an antioxidant found in fresh fruits and vegetables. Carrots are among the best sources of beta-carotene for your hermit crabs.
Marine Biology stated that beta-carotene and other carotenoids are linked to skin pigmentation in hermit crabs. So, the more carotenoids hermit crabs ingest the deeper and brighter their coloring.
Do Hermit Crabs Change Color When They Die?
One of the most common signs of aging in humans and mammals is the graying of hair or fur due to a gradual reduction of melanin in hair follicles.
However, this doesn’t apply to hermit crabs, so they shouldn’t fade in color due to natural aging. Unfortunately, this means that a gray hermit crab may be dead.
Unfortunately, dead hermit crabs look and behave similarly to molting crabs. In both instances, the skin color fades to a dull gray. Never 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 with their environment, acting as a defense mechanism for hiding from predators.
However, hermit crabs can’t change their body color. According to the Journal of Experimental Biology, hermit crabs choose shells that blend into the background.
Even then, hermit crabs usually choose shells with a clear contrast as they’re easier to find.
Changing Colors in Hermit Crabs
If a hermit crab’s skin turns red, that’s usually positive because this is the default skin shade—the deeper and darker the hue, the healthier the hermit crab.
A hermit crab turning blue is OK in breeds with this striking coloration. Equally, the dominant claw of the Caribbean hermit crab should start turning purple after molting.
The exception is when hermit crabs become trapped in their shells. The changing color is caused by the paint applied to a decorated shell, gluing the hermit crab inside, and staining the skin.
Hermit Crabs Turning Pale
As mentioned, hermit crabs losing all pigmentation and turning pale requires action. Any hermit crab that is paling should be placed in isolation to assess the cause.
Hermit crabs turning gray is quite common. It could be something as innocuous as molting or a warning sign that a hermit crab is sick.
Hermit crabs turning pure white is far more concerning. Essentially, if a hermit crab is bright white, you can see its exoskeleton.
The most common reasons for hermit crabs to fade to gray include the following:
- Preparing to molt.
- Bleaching from excessive light.
- Failing to gain appropriate dietary nutrition.
The tank could be problematic, especially if several hermit crabs are graying simultaneously.
If a hermit crab turns white, it’s very sick or dying.
The hermit crab is likely dead if others gather around a white tankmate. As per Ecology and Evolution, dying hermit crabs release specific pheromones, and conspecifics pick these up.
Your other hermit crabs are amassing because they want the vacant shell left by the deceased and may eat the carcass. Hermit crabs are natural scavengers, so they’re prone to cannibalism.
If you notice white spots, the hermit crab likely has mites.
Hermit Crabs Becoming Darker
Hermit crabs growing darker in color may have a bacterial infection.
Alternatively, a hermit crab could be stained by decorative paint. All paint should be avoided on shells, but dark paint is especially inadvisable.
Hermit crabs with black spots should bathe in saltwater. The hermit crab likely has a bacterial infection if the black doesn’t wash off.
Isolate the infected hermit crab and rehome any tank mates. The habitat must be deep cleaned, or the bacteria will harm other hermit crabs.
The skin is decomposing if the scent of rotten fish accompanies black spots.
Staining from substrate or excrement is the most likely explanation for a hermit crab turning brown.
Hermit crabs poop within their shells before flicking the waste onto the substrate once it builds up. If you stay on top of any spot cleaning, it shouldn’t cause any staining.
Using sand or soil as a substrate may temporarily discolor the skin of hermit crabs. Unfortunately, these substances can stubbornly cling to hermit crabs until they’re washed off.