Mistakes That Can Kill Your Hermit Crab

Keeping hermit crabs as pets is a fairly popular hobby. Unfortunately, in the vast majority of cases, their owners approach the care of their pets quite irresponsibly. As a result, on various forums, Facebook groups, Reddit, and so on, hundreds of threads have already appeared where people ask questions about why their pets have died, what happened, and so on.

Today, I am going to highlight the main causes of death for the hermit crabs. Hopefully, it can help you identify potential problems and, as a result, prevent the deaths of your pets.

Without further ado, let’s talk about the saddest thing for any hermit crab owner. Why do hermit crabs die?

Main Reasons – Why Hermit Crabs Die

Right from the beginning I need to say that there can be lots of reasons why hermit crabs may die. Nevertheless, they can still be grouped into categories as follows:

1. Improper habitat.
2. Physical injuries.
3. Improper nutrition.
4. Illnesses.
5. Stress.

It’s important to mention that many of these reasons can naturally intersect or influence each other. For instance, improper nutrition can potentially lead to a hermit crab experiencing stress, getting sick, and consequently, for example, being unable to molt.

1. Improper habitat

Improper habitat is the most common reason why people fail to keep hermit crabs as pets.

When we bring any pet into our home, we take on the responsibility of creating optimal living conditions for them. This applies to hermit crabs as well.

This is where the challenges may arise because replicating natural conditions in home conditions can be more difficult than anticipated for lots of hermit crab owners.

It is important to emphasize that everything that is listed as a requirement for hermit crab care matters. I would like to reiterate and emphasize once again – ABSOLUTELY everything! It is not possible to skip something and still expect that your hermits will live a long life.

Hermit crab’s setup includes:

• Size of the enclosure,
• Temperature,
• Humidity,
• Substrate,
•  

Of course, depending on the species (such as Purple pincher, Ecuadorian hermit crab, Strawberry Hermit Crab, Blueberry hermit crab, Ruggie Hermit Crab, etc.), hermit crabs will have different preferences and requirements.

Some examples:

• Hermit crabs need adequate substrate depth for molting/digging.
• Improperly placed heaters can lead to overheating, which is especially dangerous if a hermit crab is burrowed and about to molt, as it may not have the energy to escape.
• Hermit crabs need constant access to water. Deep water dishes are essential for hermit crabs to replenish their moisture balance. However, they should be designed in a way that allows the crabs to exit freely, or else they might drown.
• Insufficient or excessive humidity can result in illness for hermit crabs.

That is why it is CRUCIAL to do your own research on the specific type of hermit crab. This will help you avoid many basic mistakes that can often prove fatal for these crustaceans.

Related articles:

• Hermit Crab Tank Setup
• Hermit Crabs – Detailed Guide: Care, Diet, and Breeding

2. Physical injuries

Hermit crabs can suffer traumatic injuries. In my opinion, this is the second main reason why hermit crabs die in captivity.

2.1. Improper handling

No matter what you may have heard before, remember one thing – hermit crabs do not like to be handled. They are wild animals and cannot be domesticated. Handling stresses them.

Nonetheless, if you have to move them, it should be done the right way.

Hermit crabs are fragile and can be injured if not handled properly. Dropping them from any height can crack their shell and be fatal. Also pulling crabs suddenly from their shell will break their grip and rip off their legs. Children often mishandle hermit crabs leading to injury.

Related article:

• How to Handle your Pet Crustaceans

2.2. Falls on hard surfaces

A hermit crab falling onto a hard surface and pointed decors like stone, glass, or metal can easily crack their shell and die from impact.

Falls are common when they are placed in wire cages, or if crabs climb to escape unsuitable habitats.

Keep it in mind during preparing a home for them. So, providing nets, and a soft sandy substrate can help prevent lethal falls.

2.3. Fights between hermit crabs

Hermit crabs are social animals that tend to live peacefully together when basic needs are met. However, fights and even cannibalism can occur between them for several reasons:

• Molting crabs are vulnerable. Crabs are soft, defenseless, and highly attractive to other crabs as food during the molting process. Cannibalism of molting crabs is unfortunately common in crowded tanks.
• Size differences increase risk. Keeping multiple differently-sized crab species together often leads to bullying and attacks on smaller individuals. The size disparity puts smaller crabs at risk of being harmed and even
• Personality. Some individual hermit crabs can be more aggressive than others. Putting highly dominant individuals together will result in chronic fighting and eventual death.
• Overcrowding. When too many hermit crabs are kept together, it often increases aggression and territory disputes that can turn fatal.
• Inadequate resources. Not providing enough food, shells, and hiding spaces for all hermit crabs increases competition and aggressive behavior.

2.4. Damage during transportation

Bumping around in bags and boxes can lead to cracked shells, lost limbs, or death.

Transporting hermit crabs gently in secure padded containers can help prevent injury and death from impacts during travel.

3. Improper nutrition

In the wild, Hermit crabs are foraging omnivores. They will eat decaying plants and decomposing animal matter that they come across. Basically, it means that they will eat anything left unattended on the ground, as they are scavengers.

Nonetheless, the simple fact they are not fussy eaters by nature does not mean that we can give them whatever we like or that we should not care about their diet. This approach will only lead to weakened immune systems, diseases, problems with their exoskeleton, and their death.

Some examples:

• Lack of calcium. It causes weak shells and difficulty molting. Each molt requires huge calcium reserves to harden the new exoskeleton.
• Absence of protein. It leads to muscle deterioration and organ failure.
• Missing vitamins and minerals. This weakens crabs’ bodies and makes them prone to disease. Fruits, veggies, leaves, etc. are very important for their diet, however, acidic fruits are bad for them.
• Contaminated foods. It can cause bacterial infections that make crabs severely ill.

Hermit crabs need a varied diet with protein sources, fruits/veggies, nuts/seeds, calcium, etc.

So, if we want to give them the best life possible, we need to provide them with a well-balanced diet. We need to make sure that our pets get all the necessary microelements, vitamins, and minerals that are needed for their body to function correctly.

Related article:

• Hermit Crab Diet

4. Illnesses

Hermit crabs can fall victim to various infectious diseases and parasites, often due to poor diet, habitat, and general care. It will weaken the immune system and can rapidly lead to death.

For example:

• Bacterial infections. Unclean environments, poor nutrition, and stress can allow pathogenic bacteria to thrive. These can cause shell rot, limb necrosis,
• Fungal infections. Mold and fungus are common in humid crabitats with poor airflow.
• Respiratory infections. Poor living conditions, such as a dirty or dry environment. Exposure to cigarette smoke or other airborne irritants. All kinds of infections may cause it.

Preventing illness requires thorough routine cleaning of the crabitat, high-quality foods, and careful observation of each crab’s behaviors for early symptom detection.

5. Stress

This might perhaps be one of the most subtle killers of hermit crabs.

As I mentioned at the very beginning, when it comes to caring for hermit crabs, there is nothing that can be overlooked or skipped.

Yes, it might seem like you can get away with it at first, but in the long run, stress will have an accumulative effect. Things like poor habitat, improper handling, disrupted molting, or too much noise/activity can stress hermit crabs.

Prolonged stress weakens their immune system and health over time.

Example of Potential Causes

In the first part of the article, I provided a general analysis of potential negative consequences for hermit crabs.

In the second part, I will delve into more specific examples. I won’t categorize them further.

1. Poor diet

Certain foods can be harmful to hermit crabs, such as:

1. Processed Foods: Avoid processed foods like chips, sugary snacks, chocolate, and anything high in artificial additives and preservatives.
2. Citrus Fruits: Hermit crabs are sensitive to citric acid (like oranges, lemons, limes, etc.).
3. Dairy Products: Hermit crabs are lactose intolerant and cannot digest dairy products. They lack the enzyme lactase needed to properly digest the milk sugar lactose. Do not give them cheese, milk, or yogurt.
4. Spices and Salty Foods: Excessive salt and spices can harm hermit crabs.
5. Alcohol: Never give hermit crabs any alcoholic beverages.
6. Moldy or Spoiled Food: Always provide fresh food and remove any uneaten items promptly to prevent mold growth.

2. Failed molting

Molting is how hermit crabs grow by shedding their exoskeletons. But the process can go wrong if the crab doesn’t have enough calcium, adequate humidity, or deep enough substrate.

A failed molt is often fatal.

In some cases, there may not actually be a problem, but inexperienced owners might mistake a molting crab for a dead one.

Related articles:

• Everything About Hermit Crab Molting
• Is Hermit Crab Dead or Molting?

3. Lack of extra shells

All hermit crabs are critically dependent upon gastropod shells for their survival and reproductive fitness. Additionally, different species have different preferences for shells.

Thus, hermit crabs need a supply of larger empty shells to change into as they grow. If they can’t find a suitable new shell, the old one will restrict their growth, and stress will eventually shorten their lifespan.

Related articles:

• Hermit Crab Shells: What You Need to Know
• My Hermit Crab Has Left Its Shell

4. Chlorinated tap water

The chlorine and heavy metals like lead and copper typically found in tap water are highly toxic to hermit crabs.

Additionally, the iodine in table salt is also dangerous for the crabs. It should never be used in the preparation of saltwater.

5. Dehydration/ Suffocation 

Hermit crabs need constant access to fresh and saltwater. Dehydration can happen quickly, especially for crabs without a water pool or proper humidity, and can lead to death.

6. Injuries/accidents

Crabs can suffer traumatic injuries from falls, fights, handling, or impact in an unsafe habitat. And they can also die from getting pinched or pulled from their shells – NEVER DO THAT.

7. Poisoning shells

Painted or dyed shells may look really fun and nice but they are bad for hermit crabs. Crabs scratch and consume paint chips which are toxic to them. The same can be said about painted gravel substrates and decorations.

Remember – any ‘non-toxic’ paint claims are for humans only.

8. Pesticides in foods

Hermit crabs are extremely sensitive to chemicals of any kind. Chemical insecticides, preservatives, and contaminants in low-quality foods build up in their systems with unhealthy long-term effects.

9. Household cleaners

For example, many hermit crab owners also have cats and dogs. We treat our pets for fleas in the spring and summer. Did you know that those flea treatments that you put on your dog are highly toxic to hermit crabs? 

You just want to be really careful with certain things that you are touching and then putting your hands on.

Detergents, air fresheners, and other strong cleaners let off fumes can be deadly if directly inhaled by crabs due to their sensitive respiratory systems.

10. Interaction problems

Aggressive hermit crabs may fight, bully, or disturb more timid crabs leading to chronic stress or injury. Overcrowding increases this risk.

11. Bathing

Bathing washes away the unique scents that hermit crabs use to identify each other. Without this scent recognition, they are more likely to see each other as intruders.

Additionally, a hermit crab that has just been bathed may be perceived by other crabs as recently molted, and as a result, they may attempt to attack it, thinking it’s an easy meal.

12. Molting

Molting can be dangerous for hermit crabs in several ways:

• Vulnerable to predation. During molting, hermit crabs are soft, exposed, and unable to defend themselves. Other crabs may attack, easily kill and eat them while in this compromised state.
• Lack of calcium. Without enough calcium reserves, their new shell can form too soft or imperfectly. This leads to deformities that can impede movement or feeding.
• Failed molts. Issues like poor nutrition, disruption, and stress can all cause molting to fail. Being stuck half-in, half-out of the old shell leads to death.
• Infection. Infections can infiltrate the soft new shell while it hardens, leading to systemic infections. Fresh molts are prone to fungal growth.

13. Improper tankmates

Choosing inappropriate tankmates that are aggressive, or significantly larger than the hermit crabs can jeopardize their safety.

Oversized hermit crabs are likely to intimidate and potentially kill and eat smaller crabs, especially when they are molting and have soft shells.

14. Dirty crabitat

Dirty habitats allow pathogenic bacteria to thrive both in the air and substrate. These can cause mold, fungus, and severe infections in hermit crabs.

Excrement, dirt, and debris contaminate the substrate and water, poisoning hermit crabs when ingested over time.

15. Capture or transportation stress

It is not a secret that most hermit crabs in the hobby are wild-caught. It is very difficult to breed them in captivity.

I have already mentioned the dangers of stress, but the difference in this case is that the death rate can be high is because of poor care when these hermit crabs were captured and brought to the big brand pet stores. 

Hermit crabs may also experience stress during transportation from their collection location to pet stores or to their future owner. It can be temperature and humidity changes, vibrations, and other factors that can affect their well-being.

Unfortunately, the hermit crab owner has no way to influence what is happening because the harm has already been done.

16. Post-Purchase Stress

This stress occurs when hermit crabs experience a range of adverse conditions and changes upon being introduced into a new environment.

Here, it’s worth taking into account the fact that even when perfect conditions are provided for hermit crabs, it is not a complete guarantee that they won’t experience this stress during the initial stages.

17. Loneliness

Hermit crabs are social creatures in the wild, often living in colonies. This social interaction is extremely important for their overall well-being.

Keeping hermit crab alone can induce stress and depression. Just like in other social animals, isolation can lead to negative psychological effects. Stressed and depressed crabs may become lethargic, lose their appetite, and experience weakened immune systems, making them more susceptible to diseases.

18. Wrong substrate

Do not use calcium sand or thermal sand in a Hermit crab tank.

The problem is that humidity causes the calcium sand grains to bind (turning into a concrete-like mixture inside your crab). As a result, they cannot move or molt properly. Their gills are clogged up and eventually, crabs die.

19. Overheating

Overheating can be fatal to hermit crabs. In fact, not only overheating but also cold temperatures will have negative consequences. It’s just that when it comes to overheating, it can simply be an error made out of ignorance, but with the best intentions.

For example, it is essential to correctly position the heater, ideally on the side of the enclosure. This way there will be warm and colder areas in the crabitat.

20. Inadequate ventilation

Inadequate ventilation can harm hermit crabs in several ways:

1. Poor Air Quality: Without proper ventilation, the air inside the enclosure can become stagnant. Hermit crabs require access to fresh air to breathe properly. Otherwise, it can lead to respiratory problems and stress, which can negatively impact their health.
2. Increased Humidity: Hermit crabs need a certain level of humidity in their habitat to stay healthy. Inadequate ventilation can cause humidity levels to rise excessively, leading to a damp environment. This can result in fungal and bacterial growth, which can harm the crabs and cause shell rot.
3. Temperature Regulation: Proper ventilation helps maintain suitable temperature levels within the enclosure.

It’s important to note that some people keep hermit crabs in aquariums, which can indeed pose ventilation challenges. While aquariums are often used as enclosures, they are designed for aquatic animals and cannot provide adequate airflow for terrestrial hermit crabs.

To address this issue, hermit crab owners should consider ways to improve ventilation within the enclosure.

In Conclusion

Keeping hermit crabs is not always sunshine and rainbows.

Unfortunately, there are also many potential risks to a pet hermit crab’s health and longevity if not correctly cared for. Proper diet, habitat, humidity, temperature, substrate, shells, water quality, handling, etc. are all critical to their well-being.

Educating oneself thoroughly on proper hermit crab care before and after purchase is key to their health and survival. With knowledge, preparation, and diligent care, hermit crabs can be rewarding and fascinating pets.