Hermit Crabs can pass away for many reasons, sometimes it is due to the environment we have offered them or something we have done wrong, and other times, it can be completely out of our control.
How long can hermit crabs live?
In the wild, Hermit Crabs can live for upwards of 40+ years. In captivity, they can live to be 15+ years old. So if your crab is dying after just a few months or a year, something isn't right.
How can I tell if my Hermit Crab is dead?
It can often be hard, especially for beginners to tell if their crab has passed on or if it is surface moulting.
One of the most notable symptoms is a fishy smell coming from the crab.
But that doesnt always happen so quickly. Other common signs that your crab has passed away are as follows.
• When you pick up the crab, it falls out of its shell. This is because it is no longer alive, therefore it can no longer hold onto its shell.
• The exoskeleton is fully intact, and your crab is completely lifeless with no movement at all.
• Their eyes will be a glazed over grey or a whitish colour.
• There is absolutely no movement at all coming from the crab.
• The crabs lifeless body is outside of its shell.
• The crab is in the pool, completely lifeless and floppy when picked up.
Signs its a surface moult and NOT a dead crab
Sometimes crabs will moult on the surface due to stress or inappropriate conditions. They can often appear as if they are dead, when infact they are undergoing a delicate surface moult.
Signs of a surface moult include.
• Crab is lifeless and laying on its side.
• The crab is hanging halfway out of its shell.
• The exoskeleton has begun to shed away from the crab.
• If you look closely, you will see slight movement, jerks and twitches coming from the moulting crab.
• You find an exoskeleton on the substrate that is empty.
• When you pick the crab up, they are still holding onto their shell.
Surface moulting is very dangerous and the crab should be isolated immediately.
If you are still unsure if your crab is dead or just surface moulting, isolate them regardless. In due time you will know whether they are dead or not. If the exoskeleton is shed and there is still a crab inside the shell after a few weeks, your crab is alive and surface moulting.
If after a few weeks, there has been no change at all, and the crab is beginning to smell or is covered in mould, your crab has passed away.
To read more about surface moulting, visit our Surface Moulting Blog here https://www.happyhermie.com.au/post/surface-moulting-a-hermit-crab-emergency
What causes a hermit crab to die?
There are many reasons why your crab may have passed away. We will cover them all below.
• Inappropriate Tank Conditions
This is a big factor in crabs passing away. Low heat and humidity, incorrect and shallow substrate, no deep pools etc puts great stress on your crab and can cause them to pass away. These are very easy fixes, so having your crab pass away due to tank conditions is something that is completely preventable.
• Naked Crab
If a hermit crab drops their shell and goes naked, this is an emergency and should be dealt with immediately. Isolate the crab with a handful of appropriate shells. Unfortunately, if the crab does not take on a new shell, they will pass away. No shell is a death sentence. They need their shells to keep their soft abdomen protected and moist. Make sure that you have an adequate supply of appropriate shells for them to choose to prevent them going naked. Another reason they may go naked is due to severe stress and inappropriate tank conditions.
• Attacked By Another Crab
It is not normal for crabs to be attacking and killing eachother. They are not predators, they are prey animals and scavengers. Meaning they will eat what they can find laying around, but will not actively go out and kill for a meal.
Hermit crabs need a daily diet of atleast 50% protein. Not offering them enough protein in their diet can cause them to go to great lengths to try and fill that void. And that is when they can start attacking their tank mates and consuming their bodies. If you are finding your crabs are continually killing eachother, up their protein intake.
Hermit Crabs can drown! But not if you give them a safe way in and out of their pools. They know how to get in and they know how and when to leave. But, if there is no safe and secure way out, they will drown. This commonly happens when people put in deep pools, but do not have a secure enough way out. Sometimes ladders can be knocked and fall into the pool or rise above the water level, leaving the crab with no safe way out. This is when a crab will drown. It is important to monitor your pools and their ladders regularly.
Do not let this deter you from having deep pools, remember your crabs NEED deep pools to fill their shell water.
There is no exact time limit for how long your crab can stay submerged in the water. Some crabs have been known to spend hours on end in their pools before leaving.
Stress plays a big factor in a Hermit Crabs health. Alot of constant stress can cause them to pass away. Stressful situations include, overcrowding, handling your crabs too often, taking them out of the tank to play, digging them up, inappropriate tank conditions, digging them up, moving them around too often (from one tank/place to another), dropping them, low heat, low humidity etc.
• New Crab Syndrome
This is when you buy a brand new Hermit Crab from the pet store. By now, they have gone through a world of stress after being caught from the wild, tortured and abused, forced into a painted shell, shipped to the pet store, placed into usually, highly inappropriate tank conditions, purchased by you, brought back home and then placed into their new tank. That's enough to stress anyone out!!
Some crabs bounce back from this stress and all they need is a good distress and moult beneath the sub. Where as some crabs can not overcome it and will sadly pass away. Unfortunately, when we buy pet store crabs, there is no guarantee if they will pull through or not. Even if you offer them the best home possible, it's upto the crab now and there is nothing you can do about it.
• Digging Them Up
Digging up Hermit Crabs is very dangerous. Not only does this cause alot of stress to them, but if they are mid moult, digging them up could potentially kill them. During moulting, Crabs are extremely delicate and should not be disturbed. Digging them up and handling them during moulting can cause them to drop limbs, have a failed moult and ultimately kill them.
We cannot guarantee the health of our crabs when they are plucked from the wild. Sometimes they come to us already sick and weak. Sadly there is nothing you can do for them now. They will eventually pass away. Some crabs can contract a disease known as shell rot. This looks like a dark brown/black rot on their limb. This is extremely contagious and can lead to death. Thankfully if caught early, you can treat it. Shell rot is caused by feeding your crabs raw shellfish. All shellfish should be cooked prior to feeding.
• Being Disturbed While Moulting
Not only should we never disturb a moulting crab, but other crabs should also not disturb a moulting crab. During moulting, your crab is extremely soft and delicate. They will also give off a fresh moult smell, appealing to surrounding crabs who may be too close. They may take this as an invite to have an underground snack on your crab.
This commonly happens when tanks are overcrowded, the substrate is not deep enough, or the tank is too small. This is why it is recommended to have atleast 38L of space per crab in the tank.
• Inappropriate Diet
Diet is extremely important. Hermit Crabs need protein, calcium, vitamins and minerals, fibre, beta-carotenes, carbohydrates, healthy fats, anthocyanins, tannins and supplements.
Failure to provide your crab with the correct and balanced diet can result in a very weak, nutrient deficient crab that will die. An inappropriate diet leads to further issues such as failed moults, consuming tank mates, lethargy, slow growth, and death. Never feed your crabs commercial pet store foods or Pellets. These will not cover the diet your crab really needs.
Always offer fresh foods and high quality dried mixes as well as supplements such as greensand, worm castings and insect frass.
• Coming Up Too Early From Moulting
Most hermit crabs will moult under the substrate, consume their exoskeleton, wait for their new exoskeleton to harden and then dig their way to the surface. This is a successful moult. Some crabs will do all of those things, but will come up a step too early. Instead of waiting for their exoskeleton to harden, they come up straight away. Being on the surface with a soft exoskeleton and a fresh moult smell will attract other crabs to them. Because they are soft, other crabs can easily attack, injure or kill them to consume. If you find a soft crab, they must be isolated immediately until their exoskeleton has hardened before they can rejoin the general population.
• Failed Moult
A failed moult is when a Hermit Crab does not survive their attempt at a moult. They could be too weak, have an inappropriate diet, already be sick or far to stressed. You will know when this has happened as they will dig down to moult and that is the last you will ever see them. If you ever find yourself needing to dig up the substrate and you find their empty shell in the sand, they have passed away and decomposed.
• Shell Jacking
Shell jacking is when one hermit crab tries to take a shell that another hermit crab is already wearing. They will coax the crab out and grab one of their legs or claws with their large claw and attempt to rip them out of their shell. Hermit Crabs would rather be ripped in half than give up their sacred shell. This commonly ends in death when one crab rips the other crab in half.
• They have consumed something toxic
It is very important that you familiarise yourself with safe and unsafe foods, plants and wood before placing anything into your tank. If your Hermit Crab has consumed a toxin, it is highly likely they will die. This also includes using toxic materials in close proximity of the tank. These include essential oils, bug sprays, diffusers, chemicals etc.
You can read more about safe and unsafe foods, plants and wood here https://www.happyhermie.com.au/post/hermit-crabs-safe-and-unsafe-foods
It is normal for owners to lose a crab every now and then, especially if you find yourself purchasing them from pet stores often. However, losing crabs continually in a short period of time, such as your entire clan in one year or each crab you buy from a pet store keeps dying, and your crabs are only lasting an average of a few months to a year, the issue is on your end. You need to take a good look at your tank conditions and what you are offering them. Is your tank at the correct heat and humidity? Do you have the correct ratio of substrate at the correct depth? Is your tank overcrowded? Do you have enough shells on offer in the correct sizes? Do you offer them a varied and balanced diet? Are you handling them too much?
These are all issues that need to be addressed before you continue to purchase more crabs to replace the ones that have passed away.