In the wild, there are examples of hermit crabs living for upwards of 40 years. Sadly, in captivity, many hermit crabs fail to survive for longer than a few weeks. This implies that the physical needs of hermit crabs aren’t properly met. Inevitably, new owners learn about the care needs of hermit crabs as they go along, which can lead to costly mistakes.
Hermit crabs can suffocate and die without sufficient humidity. If there’s not enough substrate, they can die during the molting process. Toxins, such as tap water and paint, are deadly. Paired hermit crabs may fight to the death over territory or a superior shell. Impact injuries, such as falls and being dropped, can lead to death.
It can sometimes be hard to tell if a hermit crab is dying. For example, molting behaviors can resemble death. You need to be certain that your hermit crab is dying before you do anything.
Why Would a Hermit Crab Die?
As mentioned, wild hermit crabs can live as long as 40 years. Experienced and skilled owners can enjoy the company of their pet hermit crabs for decades. That requires expert care because hermit crabs are easy to inadvertently harm.
Hermit crabs are widely considered easy, low-maintenance pets for children. However, they are delicate and vulnerable to our unintended actions. Unfortunately, most hermit crabs die after just 1-2 weeks in captivity.
It’s difficult to replicate a hermit crab’s natural habitat. They are used to living free on the beach, not in a tank. Beachfront shops may sell painted hermit crabs as souvenirs, but they are living creatures. To help hermit crabs flourish, they require the following items in their living environment:
- Space – Choose at least a 10-gallon tank
- Warmth – It should be 80 degrees Fahrenheit
- Humidity – The tank must be solid and run to 80% humidity
- Substrate – Provide a sand substrate for burrowing during molting
- Water – A small bowl of water to submerge in
- Hiding places – Barriers and obstacles for hiding
- Company – Hermit crabs are social and do not enjoy living alone
You’ll also need to provide the right types of food and hermit crab-safe hydration.
Stress and Loneliness
Hermit crabs are not solitary creatures. They like to live in large groups. A hermit crab forced into captivity alone will be bored and lonely. This, in turn, will lead to stress. As with all animals, chronic stress will drastically shorten a hermit crab’s lifespan. Other causes of stress include:
- Inability to hide
- Fluctuating or inappropriate temperatures
- Poor diet or water supply
- Lack of space
- Unsanitary living conditions
- Excessive handling
A stressed hermit crab will usually isolate itself. The hermit crab may also shed limbs as a defense mechanism. Will a hermit crab die if it loses a leg? Not necessarily. Hermit crabs regenerate lost limbs over time. If a hermit crab loses multiple limbs at once, it’s unlikely to recover.
If a hermit crab died while molting, it was likely due to insufficient substrate. Hermit crabs are extremely vulnerable while molting—this is why they bury themselves under sand until the molting process is complete.
Provide around 6 inches of substrate for your hermit crabs. Play sand that you would use in a child’s sandpit is fine. Never use calcium stand as this will harden hermit crabs’ joints.
Add moisture to the substrate as hermit crabs need 80% humidity. Ensure the temperature is 80 degrees, too. This is the optimum temperature for molting hermit crabs.
Never dig up a molting hermit crab from its sandy hiding place, as this will cause significant stress. Wait for a hermit crab to surface from beneath the substrate, which could take as long as 8 weeks.
We have discussed how important 80% humidity is to a hermit crab a couple of times now. The reason for this is simple. Anything less and the hermit crab will slowly suffocate. This is why crabs require solid aquariums. A wire cage will be fatal.
Invest in a humidity gauge for your crab’s habitat. This is the only way you can maintain appropriate humidity. Use a misting spray where it’s necessary to reach this optimum level. Without this, the crab’s lungs will dry out. This process could take months.
That is several weeks of intense discomfort for the hermit crab. In addition, breathing will suffer before death. The crab will steadily grow increasingly unwell and weak before eventually succumbing. This is no way for any living thing to live – or die.
You should also leave your crab in its aquarium as much as possible. It’s fine to remove it to handle for a few moments. Otherwise, only remove the crab for cleaning and house it somewhere equally humid. You will not be doing a crab a favor by letting it roam free.
Hermit crabs have gills and occasionally need to submerge themselves in water. They cannot breathe underwater indefinitely. As per Arthropod Structure and Development, the lungs of these crabs have evolved for terrestrial living.
Nobody is certain how long hermit crabs can breathe underwater. A common theory is around 30 minutes. The crab itself will instinctively know when it needs to leave the water. This means it must be able to do so.
Leave the crab a clear path back to dry land. If necessary, provide vines and branches to climb. Before leaving the crabs unattended, perform a test. If the crab appears distressed in water, remove it at once. It clearly needs a shallower pool.
Do not leave an exceptionally shallow bath by default to minimize risk. Hermit crabs need to submerge completely on occasion. This cleans the shell and fills it with essential water. Moderate the water source in a crab’s aquarium as it grows in size.
Toxicity and Poisoning
One of the most common causes of death for hermit crabs is toxicity. Crabs purchased from seafront gift shops are particularly vulnerable to this demise. Lack of understanding of dietary and hydration requirements also leads to death.
Water is one of the most important things to consider in hermit crab care. These crustaceans need both saltwater and freshwater. This will be used for hydration, bathing, and carrying in the shell. By offering both types of water, the crab has a choice.
Hermit crabs must never be offered tap water. This contains chlorine and other heavy metals. These are toxic to hermit crabs. Tap water can cause seemingly inexplicable death.
Bottled water is fine. The bottle can also be used as an obstacle in the aquarium. Just ensure it’s not small enough for the crab to crawl into. Alternatively, purchase a water filter or boil tap water and let it cool down. Bottled water is safest.
The diet of a hermit crab is often misunderstood. Do not listen if you’re told that hermit crabs will eat anything. While these crustaceans are natural scavengers, they prefer a particular diet.
You could purchase pellets from a pet store. These are frequently ineffective. Many hermit crabs will outright reject this food. What’s more, they may contain insecticides or toxic preservatives.
The same applies to fresh food. Hermit crabs are more sensitive to pesticides than humans. Organic produce is the best. Offer a varied diet. Fruits, vegetables, and nuts are ideal. This will provide sufficient calcium, protein, and tannins.
Paints and Dyes
Many hermit crabs are placed in brightly painted shells to make them more appealing for sale. This aesthetic splendor may cost a hermit crab its life.
These paints are frequently toxic to hermit crabs. The fumes alone can kill them. Even if this is not the case, the paint chips may be eaten. The term “non-toxic paint” refers to humans, not crustaceans.
You’ll also need to be mindful of store-bought aquarium decorations. The humidity of an aquarium may make paint or dye run. Colored sand poses the same risk. This, again, leads to toxicity. Stick to completely plain and non-decorative obstacles and beautifications.
Be mindful of the use of any household chemicals around your hermit crab. Obviously, this means cleaning products used in the aquarium. Avoid the use of any bleaches or other strong chemicals.
Be mindful of a hermit crab’s small lungs, too. Simply breathing in aerosol fumes can be deadly. Do not spray air freshener or antiperspirant around your crab. Even perfume or cologne can be dangerous.
Ensuring the aquarium is fully enclosed will reduce risk. Your crab will need to come out for cleaning or handling occasionally. Never take any chances. Wherever possible, keep a hermit crab in unoccupied rooms.
Hermit crabs are always looking for new shells. Many owners aim to help with this by providing options. This may be doing more harm than good.
As discussed, paints and dyes can be toxic to crabs. Only place natural shells in an aquarium. This reduces the risk of consuming or inhaling dangerous chemicals.
In addition, think carefully about any decoration or obstacles in an aquarium. Hermit crabs may try to use anything as a shell. Wild hermit crabs often die on polluted beaches as they become trapped in plastic bottles. Consider the size of anything in the aquarium.
Bacterial or Fungal Infection
A hermit crab’s aquarium must be cleaned regularly. The humidity of the enclosure can attract bacteria or fungi. This can be breathed in or ingested by the crab. This can prove fatal.
Remember, a captive hermit crab cannot escape undesirable surroundings. An aquarium is all it has. Waste, rotting food, and discarded exoskeletons can all lead to unsanitary conditions. This will also stress out your crab, making it susceptible to illness.
Spot cleaning should be conducted daily. Aim for a more thorough clean at least once a week, ideally twice. Every few months, conduct a thorough deep clean or consider replacing the aquarium completely.
As hermit crabs do not have organic shells, they are susceptible to impact damage. Rough handling by owners or another pet can kill a hermit crab. In addition, hermit crabs are skilled climbers with poor eyesight. They may stumble and fall from a ledge.
To minimize the risk of this, provide plenty of grip. Hermit crabs use their pincers to climb. Fill the sides of an aquarium with netting and vines. These will help the crab negotiate smooth surfaces. Naturally, more substrate will also provide a softer landing.
You have to be careful while handling, too. Many people ask, “will a hermit crab die if you drop it?” The answer is – quite possibly. A fall of three feet or higher can be fatal. Injuries to core body parts may be impossible to recover from.
Conflict with Another Crab
Hermit crabs can be contradictory. As we previously mentioned, they are social animals. They like to live in pairs or groups. All the same, as per Behavioral Ecology and Sociobiology, hermit crabs can be aggressive. It is not unheard of for crabs to fight to the death.
The likeliest cause of inter-crab conflict is resources. Hermit crabs need space from each other. If they are constantly battling for the same food source, fights will occur. Without enough space, there is no escape.
Hermit crabs can also grow insecure over hiding spaces and shells. Ensure there are plenty of both in an aquarium. This means the crabs will not need to battle for privacy. Barriers can also provide escape routes and hiding places.
Hermit crabs may also battle for dominance. This will typically involve trying to remove a crab from its shell. This may happen when a hermit crab covets another’s shell. This behavior is most common in crabs that have been kept alone for too long. They forget how to socialize.
Equally, some hermit crabs are just cranky. Unsanitary living conditions or stress can make crabs belligerent. If a fight breaks out, separate the crabs. Place the aggressor in a separate area with plenty of shells. This will help it cool off and calm down.
Hermit crabs sometimes play-fight for recreation too. This may involve pushing each other with pincers or feelers. It will be clear if the crabs are fighting or playing. If neither is trying to escape, the crabs are amusing themselves.
Misunderstanding of the Molting Process
A hermit crab that is close to death will become solitary and lethargic. Unfortunately, the same can also be said about molting. It is easy to mistake a molting hermit crab for a deceased one. This leads to owners accidentally killing healthy crabs.
Be patient and initially assume that your hermit crab is shedding its exoskeleton. This will also see the crab shed body parts. It will lay immobile, waiting for its new skeleton to toughen up. This will provide the strength to move again. Never touch a hermit crab in this state.
Unless you are certain the crab is dead, do not separate the body from the shell. You may be tempted to use tweezers to remove the dead crab. Why let a good shell go to waste when another crab could use it? Sadly, if the crab is not dead, you have just mutilated it.
What Happens When a Hermit Crab Dies?
As discussed, death in hermit crabs is often confused with molting. There are some telling signs that a hermit crab has expired. The first is an unmistakable stench.
Like all animals, a dead hermit crab will start to decompose. The odor of this is putrid and unmistakable. If your room starts to smell of rotten fish, a dead hermit crab is likely. This is especially so if other hermit crabs grow excitable.
Ecology and Evolution explain how this scent of death will appeal to other hermit crabs. They will investigate the corpse and see if they can scavenge the shell. The dead crustacean may also be consumed. Hermit crabs are natural scavengers, after all.
Do not leave other crabs to take care of the body. If the crab died of toxicity, this may impact other crustaceans. The dead crab must be disposed of. You can place this in the trash or bury it. Do not flush a dead hermit crab down the toilet.
You should also thoroughly clean and disinfect the enclosure. The territory may be unsafe for other hermit crabs. Do not take any chances.
Hermit crabs are not easy, low-maintenance pets. These crustaceans require particular care and attention to survive. Focus on keeping your hermit crab alive initially. Once you have mastered this, work on providing a stimulating environment.