Why do captive lizards need calcium?

[plecoperson]

Does anyone know the answer?

The need for calcium supplementation is so common, though their food sources in the wild (and what the live food eats and the fruit etc. gets from the soil) vary drastically by locale.

I wonder what it is that's missing from the captive diet that makes supplementation necessary. I understand that it's not possible to duplicate the variety found in their natural habitat, but that doesn't really account for it.....

 

[Golden Gate Geckos]

Lisa, there is no way we could ever duplicate the natural environment for lizards in captivity. In the wild, the food they eat is indigenous to their locale and this even includes what the live prey eats and the nutrients in the vegetation. Calcium is found in the soil and rocks, and basking lizards assimilate Vit.D through their skin to increase calcium absorbtion in their bodies. Wild lizards get to chose their food which would supplement them naturally.

In captivity, they are in such a controlled environment which includes the food choices we provide them, which in many cases is not natural. For example, in the areas where leopard geckos come from, there are no crickets or mealworms... yet that is a staple diet for them in captivity.

I have yet to see any REAL comprehensive dietary or nutritional data for lizards in captivity, although we all take it for granted that supplement companies like Rep-Cal, Miner-All, Flukers, etc. have done this research. I think it would be a GREAT career field for someone to get in to!

 

[Haroldo]

I think Marcia hit it right on the head! The only thing I have to add is that there is at least one person that has done some extensive research in gecko nutrition--Allen Repashy formally of the Sandfire Dragon Ranch, has been doing diet research in the Rhacodactylus group for nearly a decade. In fact, he is in New Caledonia right now studying these and other geckos in the wild right now.

 

[plecoperson]

...there is no way we could ever duplicate the natural environment for lizards in captivity. In the wild, the food they eat is indigenous to their locale and this even includes what the live prey eats and the nutrients in the vegetation...

Right--and I think I did mention all of those points in my original post. Perhaps it is the vit D/sunlight metabolism that's the key. This would be an over-reaching condition for widespread populations of animals, unlike diet.

Calcium in particular interests me because it's such a frequent requirement as a supplement for captive animals. I raise aquarium snails and they need all kindsa supplemention/specific feeding to have shells that don't dissolve. I've never been able to get an answer, even from experts, regarding why they need careful attention paid to calcium when kept captive.

EDIT: Hmmm.... But then why do, for instance, nocturnal geckos require calcium? Do they need less than diurnal ones? I understand that they get sun exposure even if inactive during the day, but I would also think that they would hide while asleep. shaded from sunlight.

 

[ledhead]

The snail thing is more of a saltwater leaching the mats out. (Think electro plating) Salt water tanks need it also reef tanks even more.
The corals and little crusties strip it out of the water for bodies and such. Plus balancing the ph which as it raises causes everything to erode faster...

As it effects nocturnal animals I would doubt it's a sunlight vit D thing.
Its just 12x12x24 vs. 100sq acres thing.

 

[spykerherps]

I supposed if you fed year feeder insects a vary varied diet with lots of different things with enough vitamins and nutrition including calcium you wouldn't have to supplement.It would have to be really diverse and balanced. I have started to make my own gut load last few months for the food I fed all my herps. like adding ouster shell( among other things) witch is a natural source of calcium,. All though this does NOT mean that I have stoped normal supplementation just making the crickets and mealies jam packed with good stuff.

Is it possible to send in a gutloaded cricket to a lab to have it tested for nutritional value

 

[Golden Gate Geckos]

But then why do, for instance, nocturnal geckos require calcium? Do they need less than diurnal ones? I understand that they get sun exposure even if inactive during the day, but I would also think that they would hide while asleep. shaded from sunlight.

Since nocturnal geckos' skin is not adapted for UV assimilation, they rely on their diet for calcium supplementation. Leopard Geckos, for example, live in areas where some of the soil is limestone.... a natural source of calcium. All animal species have evolved/adapted for their natural indigenous surroundings to supply them with the supplements they need. When we keep them captive, it isn't possible for them to do this.

 

[plecoperson]

The snail thing is more of a saltwater leaching the mats out.

They are freshwater snails, actually.

I just don't think all the bugs and plants in nature are consuming vast amounts of calcium, all 'round the world, sufficient to keep the populations they feed healthy...there must be something else.

So if diurnal geckos were kept outdoors with similar sun exposure to the region they came from, would they then not require supplements?

 

[Haroldo]

I do understand your curiosity and I think the variety in diet that most keepers fail to duplicate is one of the reasons supplementation in captivity is important. Although there are some species in captivity that will do fairly poor if you supplement too regularly such as A. felinus. Supplement those too often and you'll have a gecko with renal failure. I think something else that we're not considering is that for the most part, keepers are concerned about keeping their captives alive. Mother nature on the other hand is not so generous all the time. Sure, wild populations might seem to be flourishing with some species, but imagine the mortality rates even from nutrient deficiency alone! I'm sure the figures are staggering.

As far as diurnal species go, the sun supplies stimulation of D3 synthesis (which aids in calcium uptake) and gives the animal a sense of psychological "well-being". I know plenty of people that keep their animals (geckos and other lizards) outside for a good part of the year. They still have to supplement their animals, but with a demphasis on dietary vD3.

 

[Gecko]

There was a study that showed geckos still have the ability to do the "D3 reaction" through there skin. The study found the gecko actually had the ability boosted beyond other lizards if I remember. It was a Hemidactylus sp.

I actually have raised a few geckos (2 Fat tails and 2 Coleonyx) without any supplementation before. It's a pain in the butt though. I did it mainly when I had a lot of free time to collect wc insects and culture a lot of unusual insects like pillbugs, snails, and some other things. Besides the beetle larvae, crickets, and roaches. I also fed a very diverse diet to these insects. I don't recomend doing this though. The insect care time alone wasn't worth it.

 

[plecoperson]

Really interesting, Gecko.

I wonder about calcium metabolism/availability to the predator in insect or plant foods, or the effect of sunlight (as opposed to artificial light) on the food sources themselves....hmmm....

 

[Golden Gate Geckos]

There was a study that showed geckos still have the ability to do the "D3 reaction" through there skin. The study found the gecko actually had the ability boosted beyond other lizards if I remember. It was a Hemidactylus sp.

I would LOVE to see that!!!

 

[Gecko]

I'll see what I can do. I can get a citation at least. I think this is it, but I don't remember for sure. I need to find the actual paper.

Carman, E.N., G.W. Ferguson, W.H. Gehrmann, T.C. Chen and M. F. Holick. 2000. Photobiosynthetic Opportunity and Ability for UVB Generated vitamin D synthesis in free-living house geckos (Hemidactylus turcicus) and Texas Spiny Lizards (Sceloporus olivaceous). Copeia 2000 (1): 245-250.

I should mention that when I did raise a few without supplementation just to be safe I collected a whole bunch of different insect types from a lot of different families and additionally from different habitats. Took anywhere from 4-8 hours of collecting bugs at a time. Overall it's not worth it if anyones tihnking about doing it. Especially when you have to be careful about where you collect . . .