Aussie winter dormancy/hibernation

Questions about very inactive hermit crabs on the surface.
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Jennie
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Aussie winter dormancy/hibernation

Post by Jennie »

Hi,

I have a question about Aussies, I know there are a lots of other Aussie members on here who might be able to help me out. I have had my crabs for 10 months, over the winter months they all went underground and I basically had a tank of sand for that time. I have changed my set up since then, at the time I had a 3ft (35gallon) tank with a 16 watt mat underneath. Now I have a 4ft (55 gallon) with two heat mats (20 watt and a 16 watt) on the walls making a corner.

Now what I would like to know is that normal behaviour? I read on Crazy Crab's export license application that they don't harvest during winter as the crabs are all hibernating and therefore can't be found. I would love to know your experiences.

cheers Jennie
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Wai
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Re: Aussie winter dormancy/hibernation

Post by Wai »

I think your hermit crabs are burying themselves during the winter months just to get closer to the heat mats. I use a ceramic heat emitter and there were at least four crabs that stayed on the surface the entire time even during the winter months. I never noticed any of mine hibernating, but ever since I switched from an under tank heater (which heats the sand) to a ceramic heat emitter (which heats the air), my hermit crabs have stayed on the surface significantly more often.
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Re: Aussie winter dormancy/hibernation

Post by ladybug15057 »

I read on Crazy Crab's export license application that they don't harvest during winter as the crabs are all hibernating and therefore can't be found.
I am not from Aus., but have heard much about Crazy Crabs and have even read their web site. Very poor care info on their site.
Majority of the time with any species if they hibernate it is for a couple reasons. Mainly they are cold. (temps around 70* F or lower) They should have temps of 71*F-73*F 22.22-22.78 C) and 78-80*F (25.56-26.67 C) for a warm side so they can regulate their body heat. (as well as ocean/sea water ponds and fresh to help regulate their body temps) Have you taken the substrate temp? (which is normally different than the air temp of a tank.)
http://crabstreetjournal.com/xoops/modu ... storyid=69

And most times a UTH mounted on the side of a tank does not do much for warming the substrate temp.
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Re: Aussie winter dormancy/hibernation

Post by Jennie »

Thankyou for your feedback Marie and Wai,

As I said over winter I had the heat mat underneath the tank. I remember my thermometer (stuck on the wall of the tank rather lowish) was reading very low but the sand was very warm. I think you are right Wai, they likely were trying to get to the warmth, porr crabbies.

As the air wasn't being warmed and on advice from another forem (not HCA) when I upgraded my tank I placed 2x UTH mats on the walls rather then underneath. I have noticed the crabs are much more active now the air is warmer but then it is also warmer weather now too. I am not sure how warm my substrate is however as I do not have a subsrate thermometer yet. The substrate next to the mats would be warm at least, I have made it very deep at that end.

Thanks for the article Marie, I have learnt alot over the past 10 months but still need to do some tinkering to get it all perfect. I will get a substrate thermometer and some more of those stick on thermomters to put on each end so I can get a clearer idea of what is happening in the tank.

What do you advice in regards to UTH placement? I do have one more mat not being used which I could place underneath but I was told having the mat underneath could lead to overheating moulting crabs and also dry out the sand in a moulter crave leaving to collapse. What are you thoughts?

Wai - what is the ceramic heat emitter? I haven't heard of those.

cheers Jennie
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Re: Aussie winter dormancy/hibernation

Post by ladybug15057 »

Regardless of whether one uses an UTH or lights there is a chance using any heating source that the hermies can become overheated. It is not singled out to one or the other so along with air temp the substrate temp should always be monitored too. They do sell electronic temp controllers to plug the warming sources into. A thermostat (not rheostat) will turn the heating device off when it hit’s a certain temp and on when it dips below a certain temp. (much like the thermostat on ones furnace in their home, Wai should be able to direct you to thermostats for Aus.) We have UTH’s on the outside bottom of all our tanks and iso’s but do have temp controllers on them all. One of the best investments I made.
Majority of our hermies here have a tendency of going to the cool side of the tank to molt. But our warm end is constant because our controllers are set at 78*F. (25.56 C)
A couple other reasons hermies will become inactive too is if the humidity is too high, or too low. This makes it very difficult for them to breath. And being too hot, they will become inactive too. (not to mention that pms can also cause them to become lethargic) Knowing ones hermies and their tank conditions helps in troubleshooting what maybe happening.
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Re: Aussie winter dormancy/hibernation

Post by Wai »

Ceramic heat emitters are shaped like bulbs, but they emit heat only. They are much more energy efficient and last longer than incandescent bulbs. Also, since they do not emit light, they won't keep blinking at night due to the thermostat turning them on and off to control the temperature. You can buy one on eBay (unless you really want to pay an extra $30 at the local pet store for the same thing lol).
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Re: Aussie winter dormancy/hibernation

Post by Jennie »

I certainly didn't find it a problem having the UTH underneath, but I was definately told to move it. Funny how advice is different in different places. One of my mats on the wall does have a thermostat with a probe. It hardly ever turns off there however.

I am worried about winter so I will move the mat with the probe to underneath when the weather cools down, I don't think it is a problem now, we are about to hit really hot weather of 40 degrees celcius for the next two months. That will work out ok as I will need to do a deep clean about March too! they are certainly active now, msotly night but often in the day too.

Has been interesting reading this site, I have never heard about calibrating my hydrometer either. So I will do that and get a thermometer for the substrate and wil get back to you with the reading.

Wai- still trying to get my head around the ceramic heaters. Do you put it outside or inside the tank?

cheers Jennie
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Re: Aussie winter dormancy/hibernation

Post by Wai »

Inside the tank would be most energy efficient, but you will have to make sure your hermit crabs can't reach it, otherwise they may burn themselves. My tank lid is divided into four pieces, so I can slip two wire clothes hangers through the gaps between them and hang the CHE inside. It works like a charm if you can manage to set it up, although it's not easy doing so.
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Re: Aussie winter dormancy/hibernation

Post by ladybug15057 »

we are about to hit really hot weather of 40 degrees
You may find you may not actually need all that much heating if you can keep a section of the substrate warmer without it. If you use air conditioning you may find you will still need the heating devices. Have you considered how you will keep a section cool enough for the hermies in the higher temps? (this can be a problem too sometimes)
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Re: Aussie winter dormancy/hibernation

Post by Wai »

True, I wouldn't stress over getting too much heat since the summer heat and hit any time.
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