Should Temp/Humidity Guidelines Change

[kuplakrabs]

Temperature & Humidity Guidelines-should they be higher? When the 70-80 guidelines were established, it seems that the majority of crabs available were Clypeatus. With the increase in "exotic" species, perhaps we should re-evaluate those guidelines.

I have been doing a bit of searching around the internet and have found some interesting reading with regard to the natural climates from which our crabs hail. Many of the "exotics" (Brevimanus, Cavipes, Compressus, Perlatus, & Rugosus) are from regions very near to the equator. Many (except the compressus) are found on the Seychelles Islands (Vanessa's Site). I found a site that has compiled information about the Average Air Temp, Max & Min Air Temps, Sea Surface Temps, Daylight Hours, Cloud Cover and Humidity for these islands. The statistics are based on data collected over a 30 year period of time at Seychelles International Airport.

http://www.pps.gov.sc/meteo/monthly%20climate.htm

I plugged all of the numbers into a spreadsheet to arrive at the Average Yearly Figures for each of the categories. I think it is rather interesting to note that the temps seem to be much higher than what is commonly indicated for care of the land hermit crab.

Air Temp...................................80.558
Air Temp Max.............................85.791
Air Temp Min..............................76.225
Sea Surface...............................81.983
Daylight Hours..............................6.925
% Cloud Cover............................63.416
% Humidity.................................80.083


Perhaps the lower end of the recommended spectrum (70 degrees) is fine for the Caribbean Crabs found along the coast of Florida to the Caribbean Islands, but may need to be a bit higher for the species native to areas near the equator. While I realize that not all of our crabs come from these islands, it stands to reason that the temps they are accustom to along the equator must be higher. This may account for some of the "inactivity" that crabbers report among their Cavipes and Brevimanus.

I don't think that 70 degrees is detrimental to these species since many crabbers seem to indicate that their crabs are fine at this temp. But there is a big difference between surviving and thriving. I have observed all of my crabs with the exception of the Clypeatus, huddled into the corner of the tank (which is kept at 75 degrees) where the incandescent moon glo bulb is positioned shining on the outside of the tank. They have been doing this since I placed it on the tank. They even hang out of their shells as if they are trying to increase the surface area that is exposed to the heat in an effort to absorb as much as they possibly can. There are several different temperature zones in my tank and the perlatus, ecuadorians, and rugosus all seem to prefer that corner. My Brevimanus are both buried at the present time, so I can't offer any observances on them.

In addition to the cozy spot in the corner, I have also observed many of the same 3 species as close as possible to the 40w Repti-Sun 2.0 fluorescent light (75 gallon tank) as they can possibly get. Many times they are in the ballast of the light fixture itself with their shells in direct contact with the light. Since it is a fluorescent light, it does not give off much heat so I would think there is no worry that they are in danger from overheating by having direct contact with it.

I am still in the process of researching the areas that are native to the crabs in the wild and if anyone has any sites they can point me to, I would be very grateful for the information. This post is simply meant to plant the seed of curiosity. It is your job to cultivate it

***update***
I have recently purchased a new fixture that accomodates the use of fluorescent and incandescent bulbs together. The temp in my tank has been around 77-79 (humidity around 78%) for the past two weeks and there has been a marked increase in the amount of activity in my tank. I still see many of the crabs up as high as they can get on the cork bark-closest to the heat source, but they don't stay parked there for long periods of time. I have taken precautions to prevent them from getting near the incandescent bulbs. I also want to add that the tank is set up in such a manner that plenty of shaded areas are provided should the crabs choose to take shelter from the light.

[moire_eel]

I agree that it seems likely that many crabs regularly experience temperatures of 80 degrees or more in the wild -- being a Florida native it is something that I have wondered about. Even when you figure in the cooling effects of coastal breezes, summer is HOT in Florida. I have mostly purple pinchers from what I have observed they seem at their most active when my temperatures are between 78 and 80. It would seem that they prefer the humidity to be closer to 80 than 70 as well. I wouldn't advocate 90 degree temperatures for hermit crabs (though I wonder if it is necessarily bad if the humidity is also high). I have a light for my tank (a 40W full-spectrum floruescent, but not a repti-sun bulb) but haven't been using it because it seems so bright. Maybe I should give it a try and see what my crabs do.

So no concrete facts to contribute whatsoever, but I think you're barking up the right tree.

[kuplakrabs]

My crabs also seem to enjoy the higher humidity-closer to 80%. It can be difficult to properly acheive without mold, but I have been pretty good about stirring the substrate to allow air to get to the lower layers and I have an air pump that is continually pumping fresh air into the tank. I have the hoses postitioned in such a manner as to create a "cross breeze" to aid in circulating the air.

Any newbies reading this post, please keep in mind that I have a large 75g tank which makes some of the modifications much more plausible than if I had a small 10g tank to work with. You can, however, stir your substrate to aerate it and help combat mold without going to the extreme of adding an air pump with several hoses (which could actually work against you in a small tank by lowering your humidity). The key for any new crab owner is to establish stable tank conditions before attempting any modifications. It is also important to note that when using any type of lighting as a heat source that you choose lower wattage bulbs that correspond with the size of your tank.

[moire_eel]

How important is stirring the substrate, do you think? I don't really want to stir mine, because I never know where my molters are (and there are lots of them right now!) I did try stirring up my marine sand because it seemed like it was getting pretty packed down, and though I tried to be careful I disturbed two would-be molters, though they had not shed their exos yet and thus weren't delicate -- just annoyed. My tank stand doesn't permit me to peek from the bottom. The little guys don't always dig all the way down in my experience anyhow.

[kuplakrabs]

Moire_eel,
I think it is beneficial to aerate the substrate, but not at the risk of disturbing molters. My crabs seem to go in cycles and when most of them are down, I only stir-very carefully I might add, the top inch or two of the EE after I mist it. When I know where the crabs are (usually on the left side of my tank) while molting I do a deep stir only in the areas I know they are not. I usually find the EE a bit compacted in some areas and find that a deep stir helps to "fluff" it up. Like right now, I only have my jumbo down (the last of my molting crew came up two days ago) and I know where he is so I took the opportunity to deep stir the entire right & front half of the tank the other day.

I am always very leary of getting too close to the molters because I fear I could collapse the air tunnel they have made to the "outside world". I can see where this would be a practice to avoid if you can't glimpse your babies from below. I can be pretty tricky when you have a lot of crabbies in one tank as well.

[moire_eel]

That makes me feel better. I know there's such a thing as anerobic bacteria, but my rationale up to this point has been that where the crabs haven't dug, there couldn't be anything in the sand for bacteria to feed on. And where they have been digging ... well they stirred it for me, didn't they?

[froggz37]

Ok.. Now Wendy, I DEFINITLY have to agree with your ideas as far as my Ruggies go. When I bumped the tempurature up to 80 they seemed much happier. I know it might be a bit higher in the direct light, but there are places for them to find shade. I also agree on humidity and I have been misting the tank a bit more often, and sometimes very heavilly, like a rainfall, and they LOVE it. I think when its very wet and very warm they seem the happiest. Keep the great ideas coming!
Jess

[Putertutor]

Hi All!

I totally agree with higher temps and humidity. When I had a smaller tank my temps were lower and the crabs weren't as active. Now I maintain 80% humidity and a range of 76-82 temp. Since there are different micro climates, so to speak, the crabs can hang out in their preferred temperature zone. The bottom line is that the activity is way up in my tanks.

[Kali_Ma]

I agree; especially with the perlatus.

I saw such a sad sight yesterday; I was at a Petco that used to be doing good with their crabs, and they had the straws in the main tank, but everyone was suffocating with 55% humidity -- the straws in particular were just lying there. It was disgusting.

I had a go at the manager, and she had a million and one excuses (but we mist them a couple of times a day; but corporate says...). The store was crowded, and I was firm (and loud) when I said, "That's why your crabs keep dying and dropping legs; they CAN'T BREATHE." She was so defensive and brushed me off, it was sad.

Every Petco in the area claims that corporate won't let them install misters on the tanks, that they don't have humidity guidelines. I'm going to have to turn corporate in to the SPCA I guess.

I run 80 degrees and 80-85 percent humidity (at the humidity peak) and I have more activity than ever I did at 72 and 70%. Crabs are tropical, even PPs.

As so many other things I've found since I started crabbing (especially concerning diet), the "wisdom" from FMR and other wholesale distributors about what a crab needs to survive is, simply put, only so much crab poop.

[kuplakrabs]

Originally posted by Kali_Ma:
As so many other things I've found since I started crabbing (especially concerning diet), the "wisdom" from FMR and other wholesale distributors about what a crab needs to survive is, simply put, only so much crab poop.

Boy, isn't that the truth. It is difficult for some to challenge the supposed "older/wiser" crab authorities. But the care for land crabs is evolving-it's a fact. Without people reading, researching and suggesting better ways, we would still be following FMR's care instructions-which we all know are inferior. FMR does not seem to want to improve the care standards, perhaps it would seem to them an "admission" that they are wrong.

Personally, I think it takes a better person (or company) to step up to the plate and revise the previous misinformation. If I felt I had given wrong information, I would certainly have no problem admitting as much and making the necessary corrections.

To me it is not a game, it is about learning to care for the crabs in captivity to the very best of my ability. I wouldn't doubt that in another year-maybe even 6 months-there will be things that we do differently than we are doing today...forever evolving-it is the way of the world and always has been. It's too bad some companies and people get stuck in that rut and can't seem to move forward.