Hermit crabs don’t experience illnesses that affect other pets, but that doesn’t mean they’re low-maintenance. You must provide appropriate care to keep hermit crabs strong and healthy.
A healthy hermit crab will retain a deep, vibrant skin color with bright, shining eyes. It should have a good appetite and enjoy digging, climbing, and interacting with conspecifics after dark.
If a hermit crab grows passive and inactive, spending most of its time hiding, it’s likely unwell. Hermit crabs are easily stressed and can be subjected to toxicity.
How To Tell if Your Hermit Crab is Healthy
You can tell if a hermit crab is healthy by watching it. Happy and contented hermit crabs will be identified through six core characteristics and aesthetics:
1/ Physical Appearance
Hermit crabs in peak physical condition will have ten intact and functional limbs, including both claws.
A healthy hermit crab should also have both eyestalks, which will move periodically, and the eyes will be a bright and shiny black.
Don’t be too alarmed if your hermit crab has missing a limb, as these should grow back during the next scheduled molt, but consider why they would have shed a cheliped or leg.
What Color Should a Healthy Hermit Crab Be?
Color and skin tone are other ways to assess your hermit crabs’ health.
Your hermit crabs should always maintain a bright and striking color unless scheduled to molt in the immediate future. In this instance, the color of the hermit crab should fade.
If this color remains consistent and striking, the hermit crab is healthy. If it starts fading to a dull gray and isn’t scheduled to molt, it’ll be struggling with its health, likely due to a nutritional deficiency.
2/ Activity Levels
Healthy hermit crabs that have fully adjusted to life in captivity will be active and curious after dark. Hermit crabs are nocturnal, so they should come to live from dusk onward.
Hermit crabs love to dig, burrow, and climb. They’ll also frequently interact in a habitat, play fighting, antennae wrestling, and clambering over each other.
If one or more of your hermit crabs remain completely static, showing little interest in movement or interaction with each other, their health is likely suffering.
Ensure this isn’t a consequence of stress or unacceptable living conditions.
3/ Behavior and Temperament
Hermit crabs enjoy the company of their kind and like to live in groups.
Within these groups, a social hierarchy will be formed. One hermit crab will likely become the alpha of a colony, and others will contentedly fall into line.
Hermit crabs will occasionally fight. They may quarrel over who will retain or earn their status as the leader of a group, or they may over appealing shells or other resources.
Even when hermit crabs experience a disagreement, they resolve their differences amicably. If hermit crabs fight, sickness could be to blame, as it’s rare for them to behave aggressively.
4/ Good Appetite
Hermit crabs should always have a hearty appetite and be ready to eat upon waking at dusk, especially if their meal is waiting for them. As soon as a hermit crab smells food, it’ll seek it out.
Sweet tastes and aromas will always appeal to hermit crabs, so consider stimulating their appetite with fresh fruit. Ensure saline water is found in a habitat. According to BMC Neuroscience, salt water activates a hermit crab’s sense of smell.
If your hermit crabs aren’t eating heartily, ensure you’re varying their diet sufficiently. As wild scavengers, hermit crabs are used to eating something different every day.
5/ Shell Usage
Hermit crabs should be able to negotiate terrain with their shell on their back. The hermit crab should be able to hide within the shell without difficulty and not try to hang outside the shell.
If you find a hermit crab hanging outside its shell, it’s likely overheating and struggling with the conditions in the habitat. Ensure the temperature isn’t significantly exceeding 80OF.
Hermit crabs also need to choose a shell that isn’t too heavy. Something is amiss if a hermit crab selected a shell and is now too weak to support its weight.
Very occasionally, two hermit crabs will share a single oversized vessel.
Common Hermit Crab Health Issues
Hermit crabs are robust but can grow unwell if not cared for approximately. Typically, any health ailments will stem from these sources:
Stress
Hermit crabs are wild animals that rarely breed under controlled conditions. Most pet hermit crabs start life in the wild, are captured ahead of the sale, and are forced into captivity.
All hermit crabs will undergo post-purchase syndrome (PPS) when first introduced to a home. Hermit crabs that experience PPS will spend time hiding, usually buried under the substrate.
PPS can last days, weeks, or months. You must never force a hermit crab to interact against its will, especially when you have just bought it home.
Once a hermit crab overcomes PPS, it’ll start emerging from the substrate and spend more time in the open. This doesn’t mean it’ll never experience such upset again.
Three common stressors impact hermit crabs:
Boredom and Loneliness
Wild hermit crab colonies rarely number less than a hundred. Captive hermit crabs forced to live in solitude grow very lonely, so always put at least 4-5 together.
Boredom is also a concern for hermit crabs. Ensure they have plenty to do, including toys, climbing frames, and hiding places.
Hermit crabs will spend most of their lives in one location, so make it an interesting home.
Inappropriate Living Conditions
As they hail from tropical and subtropical climates, hermit crabs need certain living conditions to thrive.
Tank size is important, so never place hermit crabs in an aquarium smaller than 10 gallons. Also, consider the temperature and humidity.
As ectotherms, hermit crabs grow inactive and eventually risk death if they’re too cold. Keep the temperature of a hermit crab enclosure at around 80OF.
Humidity is equally vital to keeping hermit crabs safe. They breathe through their gills, which must be kept moist, so a humidity level of around 80% is the only way to guarantee this.
Get a hygrometer to monitor humidity, misting a habitat if necessary.
Excessive Handling
Hermit crabs can learn to tolerate being handled but never actively enjoy it.
Don’t adopt hermit crabs expecting the company of cuddly, playful pets. The more you force hermit crabs into physical interaction, the more stressed they’ll become.
Toxicity
Some everyday items can sicken and kill hermit crabs, including:
- Paint. Never purchase a shell that has been decorated ahead of selling or paint shells that your hermit crabs may wear.
- Tap water. Water from a tap contains chlorine and heavy metals that kill hermit crabs. Use purified water or, better yet, bottled water.
- Cleaning materials. All hermit crab enclosures need to be deep cleaned occasionally but avoid using bleach and toxic chemicals.
- Scented candles and essential oils. These can contain airborne irritants that cause distress, sickness, and death in hermit crabs.
Aerosol sprays must also not be used around a hermit crab enclosure, especially fly sprays.
Poor Diet
As per The Biological Bulletin, hermit crabs avoid any foodstuffs that cause an adverse reaction, which means they innately understand their dietary needs.
If your hermit crab lacks calcium or protein in its diet, its health will suffer. A mineral deficiency leads to weakness in the exoskeleton, potentially causing shell rot and bacterial infection.
Ensure that your hermit crabs are eating heartily, varying their diet daily. If you spot holes in a hermit crab’s exoskeleton, increase calcium and protein intake.
Parasitic Infestations
According to the Journal of Experimental Marine Biology and Ecology, up to 150 parasites impact hermit crabs. Mites can make a hermit crab increasingly uncomfortable.
A hermit crab with mites will seek a way to relieve the constant itching. If bathing doesn’t help, a hermit crab may shed its limbs or sever its eye stalks to relieve the irritation.
Mite infestations can be hard to spot before they take hold. To minimize the risk of your hermit crab enclosure becoming overrun, regularly clean it and allow them to bathe in saline water.
