Tag Archive for pincher

Caring for hermit crabs with limb loss or other deformities

Tiny hermit crab missing both pinchers

Missing both pinchers makes it difficult to eat and protect yourself.

This guide will help you care for a hermit crab that has been attacked, lost several limbs or is suffering from molt complications. General care instructions will be outlined and special exceptions for molting crabs will be included at the end of the guide. If this a newly purchased hermit crab that is dropping limbs you should check out our information on Post Purchase Stress. PPS is a common cause of dropped limbs. Dropping multiple limbs indicates extreme stress. Not all hermit crabs can recover from this type of limb loss.

Isolate

The victim hermit crab needs to be isolated. Use a secure container that other hermit crabs can not access. The victim will remain in isolation until healthy enough to return to the main group. The time in isolation depends on the severity of the attack. A badly injured crab may need to be isolated until the next molt.

The isolation unit should have the same humidity and temperature as the main tank. (Recommended: 80F/80%)

Include a hut or some other place to hide. Shallow substrate, spare shells, food and water are all needed. Each will be discussed below.

In some cases, a small kritter keeper can be turned into an isolation unit and placed in the main tank. With the screen lid secure the other crabs will not be able to harm the victim. This is less stressful as there is no environmental changes for the hermit crab to adapt too. This also allows him to be near his tank mates.

How do I set up a proper hermit crab habitat?

Shells

If your crab is also out of it’s shell that needs to be addressed first. Our cup method is tried and true and works in all but the worst cases. Provide 2 or 3 spare shells in the isolation unit once the crab is back in a shell.

How do I get my hermit crab back in it’s shell?

Food

Eating well is vital to the recovery process. Commercial hermit crabs foods are 99% unsafe. Most include chemicals that inhibit the molt process and/or are used as a pesticide. We strongly discourage ever feeding commercial foods but feeding them to an already sick crab will only worsen the situation. A natural diet of real food is best.

A hermit crab needs both claws to eat properly. One claw holds the food while the other tears or breaks off a small bit and then brings it up to the mouth. If your hermit crab is missing one claw they can still feed themselves but you will have to alter their diet. Soft foods that do not require tearing or breaking should be fed. Calcium rich foods can be ground into a powder and mixed with another food or fed dry.

If your hermit crab is missing both claws they will have to be hand fed. This means all foods will need to be ground into a powder and moistened slightly. You will dip a toothpick into the food and bring it up near the mouth. The mouth parts should reach down and take the food. If your hermit crab will not eat from you in this way, put a small amount of food in a bottle cap. Position the hermit crab over the cap so they can simply dip their mouth into it.

Change the food daily. Keep the food dish very close to where the hermit crab is resting. This will minimize the need to walk.

A diet consisting of all the key food groups is vital for recovery. Honey can be used to stimulate appetite or give a little boost but it does not have much nutritional value. You can use honey as a base for other foods you have ground up. Kind of like putting ketchup on your kid’s food!

What can my hermit crab eat?

Water

Land hermit crabs can drink water without their claws if they are able to move themselves over the dish. Use small, shallow dishes such as a bottle cap. Keep both kinds of water very close to where the hermit crab is resting. If the hermit crab can walk a bit you can use a wide shallow dish. Change daily or when empty. Water must be treated with Prime or a similar water conditioner.

Substrate

Use shallow play sand for your substrate in isolation. While in normal conditions deep sand is needed that isn’t recommended in this scenario.

Why?

In this situation the crab most likely does not have the strength or ability to dig properly.

The injured hermit crab needs to remain above ground so you can ensure they are eating and drinking.

When the victim is ready to molt again he will be able to safely surface molt in the isolation unit. If he does not move into the hiding place you provided, carefully place it over him. It would not hurt to cover the isolation unit for a few days during the molting process to reduce stress. Shadows passing over the hermit crab signal predator danger, a cover will minimize that additional stress.

Light

Continue to maintain a normal cycle of 12 hours light and 12 hours dark. It is not critical to provide UVB in the isolation unit. If you already have a UVB light set up on the main tank and will be keeping the isolation unit inside the main tank that is fine.

Return to the colony

How will you know your hermit crab is ready to return to the colony?

Are all the limbs regenerated? At the very least your hermit crab needs both claws. This means they will be able to protect themselves inside their shell, as well as feed themselves and climb to escape other crabs if needed.

Is the hermit crab active and eating and drinking normally again?

Able to climb in and out of your water pools unassisted?

If yes to all of the above it is time to return to the main tank. When you do return the hermit crab to the colony do it when you can be around to monitor the tank for a few hours.

Molting crabs

It is rare that a molter will be attacked by tank mates. When this does occur it is a result of incorrect substrate (eco earth only or not deep enough) or a poor diet. The molter needs to be gently moved to isolation and cared for using the above recommendations. Soft crabs should be moved with a clean spoon (or something similar) so that you do not transfer bacteria or other germs to the soft exoskeleton.

A molting crab will be quite weak for a couple days. Don’t expect him to eat or drink in the first day or two. If the exoskeleton was not eaten, it should be ground up and put in a dish with the victim (in addition to the food suggestions above). If the exoskeleton was eaten, provide another source of calcium in the food dish. Remember while underground hermit crabs do not ‘drink’ but they are able to absorb moisture from the substrate if needed. The molt sac is also full of water. Normally the crab would only eat their exo while under but after an attack it is important to get them to eat anything. Don’t force food in the first 24 hours after a molt. Give the crab a chance to eat on their own before attempting to hand feed.

If the molter was wounded and has visible damage to the exo you can treat the spot with our Medicinal Wash for Hermit Crabs if you catch it early.  Damage to the exo can cause the outer layers to fuse with the soft under layer. This can lead to difficulties shedding properly during the next molt. This is a very rare time when you may want to move the crab to an isolation unit when you observe pre molt symptoms. This will allow you to monitor the molt process. They may molt perfectly fine in your main tank but if they don’t survive the molt you won’t know for months.

Tips:

Wash your hands before tending to your patient

Use a spoon to gently scoop up the victim. Dig just beneath the crab so there is a some substrate between the crab and the spoon. That will ensure you don’t injure the crab with the spoon.

 

Why do land hermit crabs drop limbs?

Lost Limbs

Hermit crab dropped leg

Hermit crab dropped leg

What is Autotomy?

Comes from the latin words autos for “self” and tomos for “cut

Autotomy can be described as self-cutting, Websters dictionary describes autotomy as a “reflex separation of a part (as an appendage) from the body: division of the body into two or more pieces.” Hermit Crabs can autotomize (drop) and regenerate (regrow) their limbs from juvenile to adult stages. The break occurs along a fracture plane located at the appendage’s base.

Why do land hermit crabs drop limbs?

The rate at which the limbs regenerate depends upon the molt cycle (Morgan, 1900; Zeleny, 1908; Bliss, 1960; Skinner 1962, 1985). During aggressive encounters, a crab will often choose to flee and autotomize (self-amputate) the limb being held so that they can escape. Other reasons why a land hermit crab may self-amputate is in response to stress, ill health, to reduce blood loss from a wound, or as a response to the presence of bacteria or pests. (Cooper, 98). There is a thin grove on each crab appendage close to where it joins the body. This is the fracture plane, along with an internal membrane. Separation occurs instantly through

Stress from fluctuating temperatures

Hermit crabs are stressed by changes in environmental factors, it is too hot or cold, humid or dry. Some times when hermit crabs lose limbs it is a sign of stress or ill health. It is important to keep your crabarium as close to the environment they are used to in the wild. That means recreating the tropics which as we know means warmth and moisture.

Aggression

There are cases where one hermit crab will act aggressively towards another hermit crab. It could be territorial or over a desired shell. In the wild a hermit crab will “throw” a claw or leg if another hermit crab tries to pull them out of their shell. This is a responsive behaviour and their limbs are built in a way that they are able to “drop” or “throw” a limb easily so they may survive an attack. This is called Autotomy.

When one crab likes another’s shell, say Crab A likes Crab B’s shell, Crab A will go up to Crab B’s shell, knock its shell ( that of Crab A) against the other crab’s shell (Crab B), causing the crab in the desired shell (Crab B) to come out and have a look at what is going on. Now the first crab will try to pull the second crab out of its shell by a cheliped or other limb. The second crab will normally drop his cheliped (grasping claw) or leg and retreat inside his shell, using his remaining cheliped to protect himself. Preferring to loose a limb instead
of losing a shell.

Illness from contaminated living conditions

There are many stores that do not meet the needs of the land hermit crabs they sell. If a tank is overcrowded, unclean and there lack of fresh water. It is important that you regularly clean the tank and remove any signs of contaminated foodstuffs or mouldy substrate.

Mite infestation

If your hermit crab tank has a mite infestation you will need to get rid of them ASAP! Visit the MITES page for more information.

Molting Complications

Another reason crabs lose a limb or a cheliped is when a crab moults and does not shed their entire exoskeleton in one piece, but instead section by section, over a number of days. Generally if they survive the moult they grow their limbs back again (regeneration) and can be happy and healthy.

Why doesn’t the crab bleed to death?

The crab does not lose blood because it instantly clots. A second membrane helps in closing the wound, creating a nub-like covering which develops into a limb bud.

What happens next? Can they regrow the lost limb?

Gel pincher regenerating Photo by Lamont Darren Medley

Gel pincer regenerating Photo by Lamont Darren Medley


Hermit crab gel limb - limb regeneration

Hermit crab gel limb – limb regeneration


A nub-like covering developing into a limb bud, which is at first transparent and slowly unfolds. After one or more moults the bud (or ‘gel limb’ as it has been described) soon regenerates to the way it looked before the limb loss and will return to full size after a few moults. Sometimes this can trigger a number of moults one after the other as the crab struggles to regenerate all limbs successfully. Sensory neurons must grow and re-establish the appropriate connections with the neural network of the ventral nerve cord if the new limb is to exhibit its original function (Cooper, 98).


Rugosus gel limb

Rugosus gel limb


C. compressus surface molt. Top most leg is a newly regenerated limb.

C. compressus surface molt. Top most leg is a newly regenerated limb Photo by Nichole Edwards.


COOPER98_fig1

COOPER98_fig1


COOPER98_fig1

COOPER98_fig1

(Fig. 1. and Fig. 2 from Cooper, 1998)

References:

Anatomy for Veterinary Technicians. Purdue University School of Veterinary Medicine
http://www.vet.purdue.edu/~lamarch/term.htm

Bergmann, M., Taylor, A.C. & Moore, P.G. 2001. Physiological stress in decapod crustaceans (Munida rugosa and Liocarcinus depurator) discarded in the Clyde Sea Norway lobster fishery. J Exp Mar Biol Ecol, 259: 215-229.

Cooper, R.L. (1998) DEVELOPMENT OF SENSORY PROCESSES DURING LIMB REGENERATION IN ADULT CRAYFISH. The Journal of Experimental Biology 201, 1745–1752 (1998)

MORGAN, T. H. (1900). Further experiments on regeneration of the appendages of the hermit crab. Anat. Anz. 17, 1–9.

William H. Amos (2003). Breaking Off. Hidden Worlds Back. Saturday February 1, 2003
URL: http://www.caledonianrecord.com/pages/hidden_worlds/story/521f67cc0