HCA: Hermit Crab Association

Hi all! So i had some questions about UVB light and vitamin D. I have had a crested gecko for over 10 years and know that without UVB exposure they cannot synthesize vitamin D3. The fix is simple: powdered diets (the preferred CG food) contain D3. Also, you can buy supplemental D3. Should we be supplementing our crabs diet with D3, failing access to a UVB capable setup?

Crustaceans do not have bones and do not use Vitamin D in the process they use to build to their exoskeletons.

ROSIEonFIRE wrote:Hi all! So i had some questions about UVB light and vitamin D. I have had a crested gecko for over 10 years and know that without UVB exposure they cannot synthesize vitamin D3. The fix is simple: powdered diets (the preferred CG food) contain D3. Also, you can buy supplemental D3. Should we be supplementing our crabs diet with D3, failing access to a UVB capable setup?

No.

Hermit crabs are not reptiles and do not, as far as we know, need UVB for calcium absorption.

Let me link a thread for you below.

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soilentgringa wrote:

ROSIEonFIRE wrote:Hi all! So i had some questions about UVB light and vitamin D. I have had a crested gecko for over 10 years and know that without UVB exposure they cannot synthesize vitamin D3. The fix is simple: powdered diets (the preferred CG food) contain D3. Also, you can buy supplemental D3. Should we be supplementing our crabs diet with D3, failing access to a UVB capable setup?

No.

Hermit crabs are not reptiles and do not, as far as we know, need UVB for calcium absorption.

Let me link a thread for you below.

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http://www.hermitcrabassociation.com/ph ... p?t=115364

Offering eggshells, cuttlebone, crushed oyster shells, and insects will give them plenty of calcium and chitin for their exo. If you choose to use a powdered calcium supplement, which IMO is unecessary since they pick at and eat bits of shell, you want to find one that has nothing else in it but calcium.



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Awesome, thanks for clarifying soilent. I started wondering about all this bc the crabitat conditions guide about lighting has some mention of hermit crabs needing UVB to make vitamin D. Perhaps it should be edited?

Where exactly does it say... i had a quick re-read and couldnt find anything...?

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aussieJJDude wrote:Where exactly does it say... i had a quick re-read and couldnt find anything...?

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I just read that there is a place where it says "in theory" but that's about it.

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My whole issue with people being told that they HAVE to have UVB when we have yet to determine if they really do need it or not, is that new crabbers are already so overwhelmed when they find out how to care for crabs properly that they stress out over the expense and commitment.

A lot of people thought these would be cheap, easy pets and are unable or unwilling to shell out a lot of money for all the extras that are suggested to them.

I just want folx to understand that UVB lighting isn't life or death and not something they HAVE to worry about.

In places where the outside temps are safe to do so, crabs could even be taken outside for 15-20 mins and get UVB that way.

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soilentgringa wrote:

aussieJJDude wrote:Where exactly does it say... i had a quick re-read and couldnt find anything...?

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I just read that there is a place where it says "in theory" but that's about it.

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If you scroll down there is a section entitled UVB. The section begins thusly;

"UVB is something that must be used with reptiles as without it they aren’t able to synthesis vitamin D and they end up suffering from extremely horrific diseases affecting their bones. In theory, our hermit crabs should need UVB as well seeing as how they are active in daylight and come from the area around the equator."

After this discussion, I think that whole part might be a little confusing to new crabbers. I would take all that out entirely and instead put in something like, 'there is some debate among crabbers as to the benefits and necessity of UVB exposure,' and just continue on to the instructions without any more discussion as to why.

Hmm. How i read it is that for reptiles they require it for vit d. However, for crabs its more of something "they have in the wild and if one can, should emulate" but never mentions its for vit D synthesis...
Dunno....

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soilentgringa wrote:My whole issue with people being told that they HAVE to have UVB when we have yet to determine if they really do need it or not, is that new crabbers are already so overwhelmed when they find out how to care for crabs properly that they stress out over the expense and commitment.

A lot of people thought these would be cheap, easy pets and are unable or unwilling to shell out a lot of money for all the extras that are suggested to them.

I just want folx to understand that UVB lighting isn't life or death and not something they HAVE to worry about.

In places where the outside temps are safe to do so, crabs could even be taken outside for 15-20 mins and get UVB that way.

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Living in South East Texas, I have opportunities to take my crabs outside. I did so once and they acted like they were on a racetrack. Zooming and scurring all over the yard. I kept a close eye and made sure the yard was safe beforehand(we don't treat our yard with anything), they just seemed to really enjoy the warm sun.

So, this personal observation lends credence to the notion that UVB does "light up their world..." as you said before.

The racing around could also have been them wanting to find cover. Big open spaces in broad daylight means birds will eat them for dinner!

I have always been very curious as to why my crabs get so active when I take them outside. I take them to a safe, pesticide-free area in my backyard (the whole thing is pesticide-free) when I want to do photoshoots or just give them a novel experience. Every time I take them out, they'll take about 10 minutes or so to come out of their shells, and then it's "off to the races" as you said, where they're all hyper-active for quite a while.

I know this excess activity is not, at least, entirely, because they are stressed. Stressed crabs don't stop and eat or drink or groom themselves or be social with one another and my crabs do all of these things when they're outside. They don't move around frantically as if their lives depend on reaching some "safe space" (and I HAVE seen them act that way before); they just move around with intent. Like they're not afraid and they know where they're going and they're just looking around, basically.

So, I've always wondered why they act this way. My (unproven) theories thus far have been:

1) The increased heat makes them more active -- but, is this because they like it or because they DONT like it?
2) The fresh air invigorates them (?)
3) It's so much brighter outside - maybe they can see better (?)
4) There are new "smells" and tastes they want to explore
5) The UVB is good for them
6) I woke them all up and now they're just awake and want to be social and explore; being outside has nothing to do with it
7) ???

So, if they can see more colors on the UVB spectrum (is that what it is - that they see more colors? They see things more vividly? Things are brighter?), anyway, whatever it is... and being outside in the sunlight with the UVB "lights up their world," then maybe my theory number 3 has actually been correct all this time?

But I think it's probably a combo of a couple of my theories all together, and/or some others I haven't yet thought of.

Crabs can see into wavelengths we can't, and that normal florescents and lightbulbs don't produce. Sunlight is the ultimate "full spectrum" lighting, providing wavelengths in both UVA and UVB as well as the visible colors we can see. Color is the reflection of those light waves, and a color can only reflect the light waves that are provided. Animals other than humans see a totally different world due to the light waves their eyes are able to pick up, above and below what we can.