Too hot?

[DragonsFly]

A few years back, I remember Kip did a "study" with his colonies, letting day temps get up around 100 degrees (F), and found that the crabs actually seemed to love it, were definitely more active in the 90's, although they did become less active and dig down as temperature rose OVER 100 degrees. Since then, I've tended to let my tanks heat into the 90's during the day, and drop down around the high 70's at night, for a more natural temperature variation. Humidity is kept high with running water in the tank during the daylight hours.

For years, this has been great, everybody apparently happy; but since we are now having a shell-rejection crisis, I'm just checking every possible thing we could be doing wrong.

QUESTION: Has anybody else been keeping high day temps? Has this been found to be a not-good thing?

[AutumnHermie]

Since I have exotics, I keep the tank 80-83 and then let the tank drop down to 75-78 during the night. When I use to have all PP's I found that mine were most active at the 85 degree level. My straws were most active at the 80 degree level, and my blues were most active at the 85 degree level.

[CallaLily]

With cooler areas to move to, 90s are perfectly acceptable for PPs. However, with an all over temp well up into the 90s (no cooler areas) I notice my PPs are all hanging out of their shells, overheated. Kip's crabitat is HUGE so I imagine he has plenty of cooler areas for them to move to if they needed. And that's the key. Allowing them the ability to self regulate their temps with a gradient.

[DragonsFly]

Thanks; yes, the temps get up to 97 or 98 as read on the thermometer up near the lamps; down on the substrate in a shady spot it is more like 80. I've never seen the "hanging out of the shells" thing; probably because the entire tank never gets that hot. Rather, I have found that (if, for example, one of the day lamps goes out and I don't notice immediately) if the day temp stays in the high 70's or low 80's, I'm less likely to see any sign that anybody has even been up and doing anything. I hardly ever actually see the crabs, since they tend to be devotedly nocturnal and I sleep at night, but before I started letting day temps climb, I really never saw them out during the day; now I will see one occasionally--usually wandering around during the day right after a molt. In the spring, after the long winter "hunker down," I'll see them at all hours for a while--"stretching their legs," maybe, after prolonged "hunkering"--but then after a while they will re-establish their "up at night, down during the day" cycle and I'll only know they are still kickin' from the tracks and disappearing food and water.

Anyway, I was just checking whether perhaps long-term temp shifts like this might be a problem. I'm grasping at straws, trying to figure out why one crab is having a crisis. It didn't seem likely that it was the temp, since there is another crab up that is not experiencing the problems that the one poor guy is having, but I'm trying to cover all the bases.

[CallaLily]

My guys are more chill in winter and more active in spring/summer too. Even though the tanks are heated during the cooler months, with temps reaching into the 80s (Near the heater temps can reach up into 90s, further away high 70s-80). In hotter months I have to shut off the heat because the tanks will be 95F+ throughout and that's when I see them acting overheated. Hotter months without heat sources, temps are still well in the 80s and they are very active day or night and eat a lot.

[Crab_Coalition]

Hi I just had this experience. My temps were consistently 95-99 and humidity the same day in and day out and everything seemed fine until last month. I am in California and the,maps started to rise outside although we keep inside temps under control. I noticed 2 crabs came out of their shells and were climbing and acting normal. The first one died after we ISO'd him. When I did, I had a heat pad on the smaller tank (one appropriate for the size) but the crab was in and out of the shell and then died. Had recently emerged from a molt.

Weeks later a second crab who came from a molt a long time ago and was living happily on the surface, came out its shell and was hanging out. Because of the pattern, I ruled out molting and targeted the surface or air as being a potential problem. My wife helped me by saying I needed to cut the heat off. I told her the PPs love it but she said these crabs live near beach conditions where the wind blows and its not always 90+, they need cool air she said. I listened and cut off the heat and guess what? The small crab went back into his shell and has stayed there. I also noticed activity had increased a bit more in the tank.

Putting the heater on throughout the winter was fine but now, with weather warming, that seems to affect the crabs so I would always keep track of the heat and maybe consider shutting it down at certain times of the day or night or whenever you feel it is right to do so based on where you live. Crabs are happier now but was agonizing when you see something like that and you cannot communicate with them directly. I always feel like they are trying to tell me in their own way and I felt bad when I failed to understand with the first crab. He trusted me and wasn't afraid of me and I felt I failed him. I now feel that in its death, I learned something that will make me a better crabber. Hoping you don;t go through the same. (-:

Interested to hear from the community as well because you guys have more experiences in situations like this and I too would like to know what you all think.

Temps don't need to be too cold either and can be in the 90's but be aware of the external temps which may multiply the effects within the tank itself. When I opened the tank it was like a sauna in there but in a good way, with fresh smelling dirt but maybe a bit too hot.

[Crab_Coalition]

My guys are more chill in winter and more active in spring/summer too. Even though the tanks are heated during the cooler months, with temps reaching into the 80s (Near the heater temps can reach up into 90s, further away high 70s-80). In hotter months I have to shut off the heat because the tanks will be 95F+ throughout and that's when I see them acting overheated. Hotter months without heat sources, temps are still well in the 80s and they are very active day or night and eat a lot.

I agree with your response. I felt like I may have been boiling these crabs at times but I will make sure to balance it between 85-90.

[DragonsFly]

I really appreciate your sharing your experience. I did notice that the crabs really, really loved it years ago when I added a small fan in each tank. I did this to help with the mold issue, and it was EXTREMELY helpful in that regard, but it was also absolutely clear that the crabs loved the moving air. They would climb up to a place where the "breeze" was streaming right over them, and hang out there. So I think your wife's reminder that tropical islands are nearly always breezy and not "sauna-like" is spot-on.

Also, although it is clear that they are more active in higher temps, it is good to remember that "more active" does not necessarily mean "happier and healthier." Since they are cold-blooded creatures, "more active" could just mean "more active," and also may mean "actively seeking more comfortable temperatures."

In general, it does seem to be a good rule of thumb to do our best to try to recreate their natural conditions as much as we can in our terribly limited captive situations. Although we can never give them their actual natural environment, the more we consider ALL the different aspects of what they are actually designed to live in, not just temperature and humidity and diet, but substrate and space and cover (dense forest-like surroundings) and moving air and etc., etc., etc., the better we can care for them.

[Crab_Coalition]

I really appreciate your sharing your experience. I did notice that the crabs really, really loved it years ago when I added a small fan in each tank. I did this to help with the mold issue, and it was EXTREMELY helpful in that regard, but it was also absolutely clear that the crabs loved the moving air. They would climb up to a place where the "breeze" was streaming right over them, and hang out there. So I think your wife's reminder that tropical islands are nearly always breezy and not "sauna-like" is spot-on.

Also, although it is clear that they are more active in higher temps, it is good to remember that "more active" does not necessarily mean "happier and healthier." Since they are cold-blooded creatures, "more active" could just mean "more active," and also may mean "actively seeking more comfortable temperatures."

In general, it does seem to be a good rule of thumb to do our best to try to recreate their natural conditions as much as we can in our terribly limited captive situations. Although we can never give them their actual natural environment, the more we consider ALL the different aspects of what they are actually designed to live in, not just temperature and humidity and diet, but substrate and space and cover (dense forest-like surroundings) and moving air and etc., etc., etc., the better we can care for them.

You are so right, and I will pass on your message to my wife. (-:

[Crab_Coalition]

Its been over 12 hours, the temp is still within parameters and the crab is still enjoying his shell. (-: It's my opinion the excessive heat definitely had something to do with it.

[DragonsFly]

My guys are <snip> temps are still well in the 80s and they are very active day or night and eat a lot.

I agree with your response. I felt like I may have been boiling these crabs at times but I will make sure to balance it between 85-90.

If your crabs are PP's, you don't have to keep it that tight. Temps in the high 70's are fine; anything over 75 F and 75% humidity is "balmy" enough for them. If you have other species, you may have to keep it warmer for them.

[DragonsFly]

Oh, I also do still think it is more natural for them to have day temps that get warmer and night temps that drop somewhat. Although I've adjusted things so that the day temps stay in the upper 80's to lower 90's now, I still have night temps dropping into the high 70's. Remember that deep substrate soaks up warmth from overhead heat lights, too, and then radiates that slowly back during the night, just as the ground does in nature, too.