HCA: Hermit Crab Association

Hello everyone! Congrats on the merge and I hope everything is going well around here! I've got a Schrodinger's Cat for you.

1. What kind of substrate is used in your tank and how deep is it?
It's a 3-1 Sand EE mix and it's about seven inches.

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?
near the back center of the tank and around 70-80 on both.

3. Is a heat source used in the tank? If so, what?
No.

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)?
Instant Ocean Salt Water as designated on the box and Fresh water (tap ) declorinated with Aquasafe.

5. What kinds of food do you feed and how often is it replaced?
I feed a mixed diet of fresh and food from the Hermit Crab patch as well as egg shells and Spirulina powder. The Hermit Crab patch food is replaced every 2-3 days, and the fresh is replaced every day when added to the tank.

6. How long have you had the crab and what species is it, if known?
Since December, they're both PPs

7. Has your crab molted, and how long ago did it happen?
About a week ago, this is both their second molts with me.

8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing?
10 gallon, soon to be 30! Screen and saran wrap over the lid to insulate the humidity.

9. How many crabs are in the tank and about how large are they?
Stiles ( Who is currently up ) is the size of a half dollar and Tonks is the size of a golf ball.

10. How many extra shells are usually kept in the tank, if any?
About 6-7

11. Have there been any fumes or chemicals near the crabitat recently?
No.

12. How often do you clean the tank and how?
The tank is spot cleaned only as needed.

13. Are sponges used in the water dish? If so, how are they cleaned?
No sponges in the water dish.


14. Has anything new been added to your crabitat recently?
Nope.

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.)?

Nothing I can think of.

16. Please describe the emergency situation in detail.

I have 2 crabs alone in a 10 gallon, Stiles and Tonks. (They're about the size of a half dollar and small golf ball respectively) I adopted them off of Craigslist last December and both were doing very well. Around June, however, Tonks ( larger of the two ) went down for a molt, and about four weeks after, Stiles followed.

Let's fast forward to about a week ago. Stiles comes up wearing the shell Tonks went down in!! ( I am sure it is Stiles because he's much too small to be Tonks ) I'm VERY worried, but decided to let it be as Tonks is sort of notorious for digging down for long periods of time, however, IF he's alive, he's down there with a shell that's probably x2 sizes too small for him. Now, also, the reason I'm asking this is because lately Stiles has been digging, A LOT. I know the rule of thumb is that you NEVER dig up a molting crab, however, this one is probably naked as his shell was stolen, but I'm also wondering if it was cannibalism beneath the surface.

Here's my question -- What should I do? Do you think Tonks is alive? Should he be found, iso'd and dug up if so? Do you think he was attacked and eaten while they were both molting? How can I prevent this from happening again? Stiles is usually so easy going I'm totally shocked and scared!

Thanks for your help.

I don't know if I can help much, but I'll do my best till someone else replies... :/ Possibly Tonks' tunnel collapsed, and he had to abandon his shell. Otherwise, it might've been taken. I know you said that it was smaller, so you know it isn't Tonks, but several have reported hermit crabs shrinking after a molt due to their exo not having fully hardened. Just double check and make sure he is a noticeable amount smaller/ is for sure Tonks. I really don't know how I can help. If you can say for sure Tonks is naked under the surface and there are no other crabs under the surface that you would disrupt the tunnels of, I would dig for him, and scoop out the substrate and iso him. But that is only if you won't be disrupting other crabs molting and he is for sure Tonks. I hope I helped, wait for someone else to reply, they will surely help you. Hang in there, and good luck!

It is more likely that Tonks switched shells before going down to molt, as many crabs do.


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soilentgringa wrote:It is more likely that Tonks switched shells before going down to molt, as many crabs do.


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Thanks for your advice. I really hope that is the case!

If you can absolutely track the shells they had on and what is above ground and know for certain that a shell was stolen, personally I would dig. By this point it would probably be too late, but a naked crab underground is not a good thing if he is still alive. However, if you have any doubts, then wait. Like SG said, they often change before they go down and it's very hard to be sure! Just because you think they swapped with each other doesn't mean that is the case.

Although, I've learned to listen to my gut over the years. If it said dig, I went digging and it always resulted in a rescued crab. When I waited, well, the outcome wasn't too good. I know it's not scientific and it can fly in the face of recommendations, but it's been right so many times that I don't ignore it anymore. We can give you all the advice in the world but without being there and knowing all the details, sometimes it can only be educated guesses.

Well, I sided with Wode. My gut said dig when it never does in my 15 some odd years of crabbing. I dug today and I came up with absolutely nothing. Any ideas guys?

When a crab dies under the surface they break down rather quickly. The other crab may have also...helped the process along as much as that disturbs us. I'm sorry for your loss. the shell will be found empty if a crab died underground . This time it appears it was changed into by the remaining crab when found.

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Thank you, Kelly. As someone who has mainly kept one crab this is a bit of a shock.
Can you please tell me how I can prevent this from happening again? Or was this beyond my control? I feed them a good diet to prevent the need for something like this to have happened. Is this a common occurrence when you keep more than one crab together? Or was this just a molt gone wrong? I still have three other crabs - will they be safe with Stiles? I'm sorry I'm at a loss.

As for the 'why', in order to encourage them to eat their exoskeleton, they emit delicious crab odors during the molt...sometimes resulting in cannibalism.

I was pretty sure my crabs had dug down in order to eat each other, but they ended up fine...have you heard any noises? Like scratching on the tank? Maybe move the tank around to look under and see if you can spot him on the bottom?

I would be super nervous to dig up a molter, does he have another shell to change into?

Unfortunately I've already dug and come up with nothing and I went through every bit -- I'm afraid he's passed.

Is there any way I can prevent this from happening again? Can he be put in with the other crabs? Or do I need to isolate him permanently?

I would think it shouldn't happen again - your substrate depth and everything else sounds fine, so I would consider it a freak accident. It's possible he died of something else, and the other crab stumbled upon him afterwards and had nothing to do with his death. Did you find another empty shell?

I'm really sorry for your loss Stuff happens, and it's nothing you did or didn't do.

If you didn't find an empty shell you have an escapee on the loose!

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I found the empty shell that was switched out of and into the shell that was taken in a small molting cave, but I'm assuming it was not the passed crab's however as the cave was too small

Thank you all for your kind words I'm very relieved to know it was all an accident, even if it was at the cost of one of my crabs.

If there was an intact cave around the shell, he wasn't eaten and he wasn't attacked. They back-fill their tunnels (and the cave) as they dig and it's the calling card of another crab having been involved to find a shell or molter packed tight in substrate.

What might have happened then, Wode? It was the shell that the other crab was wearing when he went down packed in a molting cave with a few bits of Exo inside it.