HCA: Hermit Crab Association

I am sad to report I lost my favorite crab, Uno (so named because she only had one eye), early yesterday morning. She seems to have died from a sort of wasting disease, and I was wondering if anyone had seen anything like this before? I've owned crabs for 10 years, and I've never experienced anything like this.

About a week ago, I noticed Uno was not curled in her favorite spot by the heater. Instead, in the middle of the day, she was on the "cold" side of the tank, curled into her shell. She stayed there for several days, which was very unusual. I finally saw her move, and she staggered around sluggishly. She also developed a ravenous appetite. I put a teaspoon of honey in a shallow dish near her, as well as shallow dishes of fresh and salt water. I refilled these dishes each morning and evening, and they were always empty, never spilled. For days she behaved this way, never coming out of her shell or moving more than an inch from her little sickbed, but always emptying her dishes. Then, after days of this, I checked the tank to find that Uno had hopped out of her shell and streaked across the tank to the freshwater pool. She was completely submerged in the deep end, and motionless. I grabbed a cupped shell to gently move what I thought was her body, and she recoiled from me. Amazingly, this crab was alive! I moved her as gently as possibly to the isolation tank, and covered it with a blanket. After a few hours I checked, and she was back in her shell. I refilled her dishes and left her. Over the next two days, she would hang limply from her shell, barely moving, yet every time she was presented with food or water she devoured it within hours.

That brings us to yesterday morning, when I slowly moved the blanked to peek into the isolation tank. Uno had once again crawled out of her shell, but this time she was hunkered down in the substrate, dead. I sadly collected her body, and noticed something very strange. Uno's abdomen (or tail, if you prefer) was shriveled and hard, almost calcified. I had checked on her only hours before, and the conditions in the tank were perfect, with plenty of humidity. Her body had no time to lose its moisture, and besides she had been gorging herself for a week and a half. The abdomen should have been at least plump and soft, if not expanded with the abundance of nutrients! I've had plenty of dead crabs in my time, and have never seen an abdomen look like this before. Does anyone know what may have been the cause?

OMG im so sorry :'(
I'd be beside myself!

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Thank you, I'm pretty upset that she had to go in such a sad way. Uno was such a tough crab, I was sure I'd have her for at least 10 more years!

This does sound strange. Just to cover all bases, could you fill out the emergency template?

1. What kind of substrate is used in your tank and how deep is it?
The substrate I use is eco-earth, and at the deepest part it is 6-7in deep.

2. Do you have gauges in the tank to measure temperature and humidity? If so, where are they located and what temperature and humidity do they usually read?
My gauges are located on the back wall of my tank, and read at 75-80% humidity and 70-75 degrees F.

3. Is a heat source used in the tank? If so, what?
There are two sources of heat in the tank. The first is a UTH against the back wall, and the second is a lamp that is set on a daytime timer.

4. What types of water are available (fresh or salt) and how is the water treated (what brands of dechlorinator or salt mix and what ratio is used to mix it)?
Fresh and salt water are available in this tank. Both are pools that are at a slant, with a deep end to allow them to submerge. I use All Living Things soaking salt, and Terafauna Aquasafe dechlorinator.

5. What kinds of food do you feed and how often is it replaced?
The menu in the tank is varied. There is, constantly, dried fruit, a source of calcium, and dry food (such as cereal). In addition, they also receive fresh fruits, vegetables, fish, peanut butter, honey, and chicken.

6. How long have you had the crab and what species is it, if known?
I have had Uno for years, not sure exactly how long. Uno was a purple pincher crab.

7. Has your crab molted, and how long ago did it happen?
Uno has molted several times with me. The last time was about 3 months ago.

8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing?
The tank is a 40gal, with a screen lid modified to retain humidity.

9. How many crabs are in the tank and about how large are they?
In this tank there were 6 crabs, all of them medium sized.

10. How many extra shells are usually kept in the tank, if any?
There are at least 15 extra shells kept in the tank.

11. Have there been any fumes or chemicals near the crabitat recently?
There have been no fumes or chemicals near the tank ever.

12. How often do you clean the tank and how?
The tank is spot-cleaned each day, to remove old food and any dung that I can see. The water bowls are also cleaned out daily. As long as there are no molting crabs, the tank is deep cleaned once a month. The crabs are moved to a smaller tank, and all of the furniture, extra shells, gauges, and toys are removed. The gauges are checked for accuracy, and the shells/furniture/toys are all cleaned in boiling water. The substrate is all removed, and the tank itself is then cleaned with boiling water, and checked for cracks or issues. Then fresh substrate is added and moistened, the furniture, shells, and toys are added, and the gauges are replaced. As the humidity and heat levels come back to normal in the clean tank, each crab is examined individually before being put back into the tank.

13. Are sponges used in the water dish? If so, how are they cleaned?
Sponges are not used in the water dishes.

14. Has anything new been added to your crabitat recently?
Nothing new has been in this crabitat for months.

15. Is there any other information you would like to share that might be helpful (anything that is regularly part of your crab care, playtime, bathing, etc.)?
These crabs are rarely handled, but do get to roam out of the tank once a month. Unless a new crab is being added, I do not bathe my crabs (there has not been a new crab added to this tank in over a year).

16. Please describe the emergency situation in detail.
I am sad to report I lost my favorite crab, Uno (so named because she only had one eye), early yesterday morning. She seems to have died from a sort of wasting disease, and I was wondering if anyone had seen anything like this before? I've owned crabs for 10 years, and I've never experienced anything like this.

About a week ago, I noticed Uno was not curled in her favorite spot by the heater. Instead, in the middle of the day, she was on the "cold" side of the tank, curled into her shell. She stayed there for several days, which was very unusual. I finally saw her move, and she staggered around sluggishly. She also developed a ravenous appetite. I put a teaspoon of honey in a shallow dish near her, as well as shallow dishes of fresh and salt water. I refilled these dishes each morning and evening, and they were always empty, never spilled. For days she behaved this way, never coming out of her shell or moving more than an inch from her little sickbed, but always emptying her dishes. Then, after days of this, I checked the tank to find that Uno had hopped out of her shell and streaked across the tank to the freshwater pool. She was completely submerged in the deep end, and motionless. I grabbed a cupped shell to gently move what I thought was her body, and she recoiled from me. Amazingly, this crab was alive! I moved her as gently as possibly to the isolation tank, and covered it with a blanket. After a few hours I checked, and she was back in her shell. I refilled her dishes and left her. Over the next two days, she would hang limply from her shell, barely moving, yet every time she was presented with food or water she devoured it within hours.

That brings us to yesterday morning, when I slowly moved the blanked to peek into the isolation tank. Uno had once again crawled out of her shell, but this time she was hunkered down in the substrate, dead. I sadly collected her body, and noticed something very strange. Uno's abdomen (or tail, if you prefer) was shriveled and hard, almost calcified. I had checked on her only hours before, and the conditions in the tank were perfect, with plenty of humidity. Her body had no time to lose its moisture, and besides she had been gorging herself for a week and a half. The abdomen should have been at least plump and soft, if not expanded with the abundance of nutrients! I've had plenty of dead crabs in my time, and have never seen an abdomen look like this before.

I am so sorry to hear of your crabs death. Thank you for filling out the emergency form.

I am not an administrator but a couple of things stood out to me.

Purple pinchers should have a temperature range of 75 to 85. 70 is too cold. I have found that if a crab is too cold that it will hang out right in front of the heater. You could try insulating your tank if you haven't as long as it is safe for the type of UTH that you have. Your UTH should cover most or all of the back of your tank above the substrate.

Hermit crabs need a marine grade salt water as it has over 70 elements dissolved in it and mimics ocean water. Instant Ocean is the most recommended brand.

I do not use eco-earth but I know some long term crabbers do on this site so maybe they will chime in. However, I do not think it is ever necessarily to change it especially monthly. The most commonly used substrate is a mix of play sand and eco-earth at a 5 to 1 ratio. Personally I never change my substrate. I like to mix it up every couple of years but rarely have every one up at the same time.

Thank you for your response! I apparently made a typo, my temp ranges from 75-85 degrees. As for the substrate, you're right, I change it very frequently. However, that has only been for the past 5 months, as I was battling fruit flies that were coming into my tank from outside sources. I should have worded my answer better, I tried to say the crabs have a pool of fresh water, a pool with the soaking salt, and a pool with instant ocean. I have two crabs that were raised on the soaking salt and refuse to touch any other salt water.

Again, thank you very much for your response. Any and all insight into what could've happened is very much appreciated.

I had something similar, except the crab was only a month old and never moulted... I just assumed PPS. But in your case, I think its unlikely.

Do you think its possible that the fruit flies would have introduced some parasite that infected the crabs? Dunno, thats the only thing that seems weird so I'm assuming parasites/diseases/viruses.

That is as good a guess as any. Hermit crabs are such complex little guys, and we've only scratched the surface on what we know about them! I think you've got to be right, that somehow she got a parasite or some foreign illness. None of the other crabs have shown any signs of having caught it, so I can only hope this was a freak occurence and move on. Thank you for your help everyone!