UVB Lighting Too Powerful?

[DivineFromBehind]

Hello fellow Crabbers!

This is my first post, so please let me introduce myself. I am a returning crab owner; I used to have a few hermits back when I was a young lad, but never cared for them correctly. I am now an adult with a rekindled love for hermit crabs. My lady and I picked up 3 crabs (Yellow-Belly, Rapid Dave, and Americano) from a beach shop in SC, and took them back home where we could get them a proper Crabitat.

This has been quite the learning process, but within 48 hours of purchase we had our brand new crabs in a 20 gallon tank with 5 inches of substrate (I used 5:1 playsand/eco-earth). They have many extra shells, dc freshwater, dc saltwater, real food to eat, a moss pit, hiding options, and plenty of climbing options. I would like to make it known that in my research I realize the damage I've done by purchasing these little guys from a beach shop. All future crabs will be rescues. :/

Anyway -- In the beginning (keeping conditions at roughly 80/80), all my crabs dug down and wouldn't really show themselves. After a LOT of reading on this forum and others, I found this to be normal. Frankly I thought they were molting. However, it would appear that they would move around at night and definitely were getting into the water and food dishes. Perhaps they are just getting used to their new environment? At this point, it had only been 72+ hours since I moved them to their new large crabitat.. I wasn't sure what to think, so after even MORE reading, I decided to buy a UVB light to set up a day/night cycle and to hopefully boost activity in my crabs.

Fast forward to today -- it is day 3 of their new day/night cycle with my new Reptisun T5 HO 5.0 UVB light. It is the 24watt/22inch tube version. Yellow-Belly seems to want to stay above ground now during the day; Rapid Dave seems to be molting (he's deep in the substrate, hasn't moved in 2 days); and Americano is dug down into the substrate, but was up and about last night and this morning. Yellow-Belly ALWAYS hides from the light. This leads me to the reason I am making this thread in the first place:

Did I buy a bulb that is too powerful for hermit crabs in a 20gallon long tank? After a lot of research on the UVB subject, I gathered that more = more, especially if the rays are going to be restricted by a metal screen (like in my case). But I am REALLY concerned about the health of my crabs, and the fact that they never seem to bask in the UVB light makes me think that perhaps it is too strong for them and may be hurting their eyes!

Can I get one of the pros here to weigh in on this? I want to make it clear that Yellow-Belly will still have his shell stick out in the UVB light, but doesn't really like to be out in the rays and have his exo exposed for very long... It doesn't seem "scared" if it, but it will certainly move out of direct UVB light. Because Rapid Dave and Americano are digging/moltng, they aren't really helping me test any theories -- should I just wait it out a few more days to gauge their response? Is the bulb way too powerful? Please help. I want these little guys well-taken-care-of, and don't want to hurt them.

Thank you all in advance. For reference, Rapid Dave is a small and the other two are small/mediums!

[Happyhermiehome]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

[wodesorel]

What is the distance given for the bulb you bought? And is it set up above/below the lid?

[DivineFromBehind]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

Thank you, I am very happy to be part of such a helpful, loving community. I believe they are PPs. Yellow-Belly definitely is (amazing color, he's so purdy), I believe Rapid Dave is a PP as well, but we haven't seen enough of Americano to be certain (he's in a shell that's way too big for him, I want him to change so badly!)

I am using the UVB after reading countless anecdotal reports of increased coloring and crab activity with the presence of UVB lighting. Heating hasn't been a problem so far so I haven't looked into incandescent lighting or anything.

[DivineFromBehind]

What is the distance given for the bulb you bought? And is it set up above/below the lid?

I just looked it up again and the manufacturer recommends 12-24" from light to reptile. In my use, the bulb is approximately 6-10" away from the crabs, with the majority of time ~10".

The bulb is in a fixture that sits atop my wire screen. My thoughts are that the screen is blocking a significant portion of the rays, that's why I wasn't too concerned about the manufacturer's recommended distance. Frankly I wanted the T5 HO 10.0 UVB Bulb, but just was using the 5.0 because it came with my fixture. Now that I have seen the crabs hiding (it's not like they weren't hiding beforehand too..) I have begun to think I should have went for the T8 Bulbs which, reportedly, put out 50% the UVB Light of the T5 Bulbs.

On a side note - I just returned home and caught Yellow-Belly with his legs and face all pointed out, chilling towards the UVB lighting! Maybe he does like it, and is just afraid to be so exposed while THE GIANT (me) is around to watch him... My God these little things are interesting!

[wodesorel]

With the HO bulbs not a huge amount gets filtered out by screens. Is there any way you can lift the light to get more distance? In reptiles, being too close to the bulbs will cause skin burns and severe eye damage. I don't worry so much about burns since crabs have exoskeletons and we don't even know if UVB penetrates, but I would be concerned about eye damage.

[GotButterflies]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

I just wanted to mention that I have UVB on all four of my crabitats - I have PP's, Straws, Lilas, and Es. UVB is beneficial to all crabs.

Edit: I also have a UVB bulb on my Zoeae too

[soilentgringa]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

I just wanted to mention that I have UVB on all four of my crabitats - I have PP's, Straws, Lilas, and Es. UVB is beneficial to all crabs.

Source?

Not trying to come across as salty but if you have any research to indicate that UVB is in any way penetrating their exo (since ot won't through their shells) and they're typically not active in the daytime, that would be beneficial to know.

Like, what exactly does UVB do for them, since they don't need it to process calcium like a reptile would?

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[GotButterflies]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

I just wanted to mention that I have UVB on all four of my crabitats - I have PP's, Straws, Lilas, and Es. UVB is beneficial to all crabs.

Source?

Not trying to come across as salty but if you have any research to indicate that UVB is in any way penetrating their exo (since ot won't through their shells) and they're typically not active in the daytime, that would be beneficial to know.

Like, what exactly does UVB do for them, since they don't need it to process calcium like a reptile would?

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No saltiness taken From here: http://www.hermitcrabassociation.com/ph ... hp?t=68010
Edit: No research stating what it does, just trying to mimic natural environments

[wodesorel]

It really does seem to have an effect, and I agree it needs to be said about all crabs since usually it is only straws that are mentioned.

The truth is we don't know why it works. I very much doubt it has anything to do with exoskeleton production, they do not utilize Vitamin D in their calcium channels. The exo would act as a giant sun blocker. My guess has always been that it lights their world up the way it is meant to be seen, since we know other arthropods can see far into UVB and UVA.

There is enough anecdotal evidence to say for sure it is beneficial, but not enough to say that it is a must have for keeping them healthy. (Jon and Kate would not have lived to 40 if UVB was a necessity.)

[soilentgringa]

I wish we knew more about them in general. It seems like a lot of the research was done in the 70's to 90's.

If I was well enough I'd go to school for carcinology and maybe I could in the future.

Just get a research grant and live with the crabs for a while.

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[wodesorel]

Could you really dissect them for science though? That is the only way to find out what really happens in their bodies when exposed to UVB.

[soilentgringa]

Could you really dissect them for science though? That is the only way to find out what really happens in their bodies when exposed to UVB.

I think that if they died of natural causes and I didn't have to kill them I would be able to but I don't think I could purposely incapacitate them for science.

I'm sure it was difficult for you to do the necropsy with the gill mite pics but I didn't even know gill mites existed before that.

My sister had to collect over 50 lizards for her research lab and they all had to sacrifice their lives for the cause

I'm probably too much of an empath to purposely put a creature to death, unless there was no other hope for it and it would suffer otherwise.



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[Happyhermiehome]

What kind of crabs do u have? If u got them at a shore shop they are most likely purple pinchers and I don't think they require UVB light. Some exotic species like strawberrys do. I'm no expert but I would not use it and just use the normal day and night bulbs.

Welcome to HCA

I just wanted to mention that I have UVB on all four of my crabitats - I have PP's, Straws, Lilas, and Es. UVB is beneficial to all crabs.

Edit: I also have a UVB bulb on my Zoeae too

Ohh okay thanks