Crested Gecko Myths

by Anthony Caponetto

I've listed below some widespread myths and misnomers that I have seen swirling around on the internet and when I talk to my friends and customers. I think what's most alarming to me is that this stuff is being treated as common knowledge, and people - even myself at times - are actually picked on for not "knowing".

I don't have the time, nor desire to correct every bit of BS every time I see it, as people who pass along misinformation are usually there to build a reputation as an expert (and a fan/customer base) and they really don't appreciate being challenged or told they're wrong, particularly in a public setting.  They'll never concede the fact that they haven't actually experienced what they're describing, much less that it's nonsense.  That being the case, I figured this page would be a good idea for helping new and not-so-new crested gecko keepers sort out the fact from fiction - in a setting where no one is being called out individually.

The point here is to dispel any potentially harmful misinformation, so that our geckos don't needlessly suffer, and also so that keepers and breeders can feel confident doing what works for them, without being publicly shamed for it. 

My goal here isn't to embarrass anyone, but to dispel the myths themselves.  If you've been on a soap box, ridiculing others for not "knowing" these myths are true, you might want to get to deleting some posts.  And in the future, maybe think twice before you shame someone for how they keep or care for their geckos. 

Myth: Cohabbing is dangerous and a bad idea. And you're a bad keeper for doing it!
This is total bulls**t, unbelievably widespread and the people spreading it need to be put in check - this ridiculous topic gets its own page HERE.

Myth: Dalmatian spots can "pop up" in offspring from Non-Dalmatian parents.

Not true.  Dalmatian has been known to be incomplete dominant since Philippe de Vosjoli noted it back in the early 2000's.  There's no such thing as a gecko without visible Dalmatian spots that carries the gene for Dalmatian.  A heterozygous gene carrier for Dalmatian spots is called a Dalmatian.  The homozygous gene carrier is called the Super Dalmatian.  For a non-Dalmatian pair to produce Dalmatians, I would contend that either someone didn't see a spot somewhere on one of the geckos in the pair, or there's sperm retention at play. 

If you have two visually distinct genotypes, like Dalmatian and Super Dalmatian, it's *genetically impossible* for there to be a third phenotype or physical expression of the gene.  You can only inherit a gene copy from each parent and there are only two alleles located at a particular locus.  In other words, if the gecko isn't a visual Dalmatian or Super Dalmatian, then it's not possible for it to be carrying the Dalmatian gene.

Note: One thing I have seen on a few occasions are Dalmatians that only had spots on their tails...odd, but it happens.  If one of those geckos were to drop their tail, there would be no visible spots left on the gecko.  This could easily lead someone to believe there's a gene present, but not being visually expressed.

Myth: Crested Geckos won't, or shouldn't, eat mealworms.

This is a myth that started in the leopard gecko world, but applies to crested geckos just the same. This one is actually really interesting, and I was really excited when I figured out what the problem/cause was, and that mealworms are a viable and convenient source of insects.

I actually played a role in propagating this myth when I stated that mealworms left in the cage often went unnoticed by the geckos. It wasn't until years later that I decided to try putting mealworms in a dish, which I must say works well, but only once the geckos have figured out that mealworms are food.  I didn't buy into the fact that they couldn't be digested, just that I thought crested geckos wouldn't be attracted to them as a food source.

So, the Mealworm myth goes like this...

"Crested geckos shouldn't be fed mealworms because they have trouble digesting the exoskeleton (or "shell"), and they're not a very good food source anyway."

OK - First of all, mealworms are a fine food source, so get that out of your head. They are high in protein and relatively low in fat, even compared to crickets.

Secondly, leopard and crested geckos have a digestive enzyme in their stomachs called chitinase which is there specifically to digest chitin - the very material that the exoskeleton or shell is made from. 

PS: No one in the crested gecko hobby seemed to know about chitinase until I pointed it out here. Now I see competitors talking about chitinase in their posts and videos.  You know who you are...and if you'd like to plagiarize more content, please go have a look at my cohabbing page.  ;-)

So where or why did this myth start?
Most people offer mealworms in a dish to keep them from burrowing under the substrate or paper. For a gecko that's used to hunting for insects, a dish full of mealworms is literally the proverbial "fish in a barrel" scenario. This can be problematic for a gecko that's used to having to hunt and work for it's insects. To a gecko that has never seen such a wonderful sight (a dish full of insect larvae that can't run away), they will try to eat as many as they can, effectively gorging themselves to the point of regurgitating. What they regurgitate typically resembles a little football shaped clump of undigested mealworms. It's easy to see how someone who didn't know any better could think this is because geckos can't digest mealworms, especially when that's what everyone on the internet has been telling them.

I've seen this phenomenon over and over again when breeding leopard geckos and also with crested geckos. Fortunately, once your geckos start to see a dish full of mealworms as a normal thing and not a one-time opportunity to pig out, they will quickly learn not to do gorge themselves. The best thing you can do is to limit the number of mealworms you offer your gecko(s) at first. Once the gecko has gotten accustomed to seeing mealworms in a dish, it won't be as likely to go bonkers attempting to eat every last one of them.

Myth: Males and females must be separated in the off-season.

This is a myth that started a long time ago. I'm not sure why the breeder who started it did so, but I believed it, and I separated my geckos every year for several years. I also passed this misinformation on for years, regretfully. As my collection grew, this process became more and more of a pain in the neck, and I decided that it made no sense to me. Who separates them in the wild?

So that was it - I decided to leave my breeders together all winter and see how it went. The geckos did fine. Contrary to the myth, males do not continually harass the females in the off-season. This is because males are attracted by the pheromones they detect on a female who is actively producing follicles and eggs. If the female isn't ready to be bred, she won't be producing the pheromones that makes the male want to breed with her.

Some breeders have told me they prefer to separate males every year, and that's fine - there's no harm that can come of that.

The next time someone tells you separation is necessary, ask them who separates the males from the females in the wild. :-)

Myth: Crested Gecko morphs are random and are too complicated to predict what a pairing will produce.

Note: This is an old one - which I think we've now all come to know was completely untrue and has finally died out, thanks to several genes being proven in the species.   I'm leaving this here so people will see what kind of nonsense can be spread through our hobby as "fact" by ignorant people who are pretending to be experts.

Unless someone is talking about how an independent gene or trait is inherited, I wouldn't pay any attention to what they're saying because it's likely nonsense.  Most colors and traits in crested geckos are inherited in an allelic (genetic) fashion...either incomplete dominant or recessive, just like most ball python and leopard gecko morphs. The intensity of certain pigments (like Tangerine) and extreme forms of certain markings (like pinstripe) can be selectively bred for, but that also holds true with ball pythons and anything else.

Without getting too lengthy, the reason we get several different phenotypes or "morphs" from a single pairing is because there are multiple genes being inherited from each parent, all with separate 50/50 odds of being inherited. Even if there were only are 2 genes that make up an appearance (unlikely), you would still get up to 4 different phenotypes. If there are 3 genes then you get 8 possible phenotypes, with 4 genes you get 16 possible phenotypes, 5 genes you get 32 possible phenotypes. As you can see, odds can get long, and certain phenotypes or appearances will appear to the average breeder to be a random one-off appearance, when in reality they just hit on a 1-in-32 gecko from a pair that might only produce 12-16 eggs a year.

That's why we're breeding for "supers" in any trait where a super is possible. With the super form (or homozygous form) of a morph, you know that one copy of the gene/trait will be passed along to all of their offspring, and those pesky odds are removed from the equation for that particular gene/trait. If you have two supers in a pair, then you know the offspring will get one copy from both mom and dad, and therefore all offspring will be supers.

If you understand ball python morphs or leopard gecko morphs, this stuff is all pretty elementary - unfortunately a lot of crested gecko breeders have no experience with other species or morphs, and they tend to not only believe the misinformation they've been given, but pass it on to others as well.

The fact of the matter is that if you breed a pair of geckos repeatedly for enough years, you will absolutely see the same phenotypes (or combination of traits/colors) appear time and time again. Some will be relatively common from that pairing, and others will seem more sporadic - that's all because of genetic odds and how many genes are involved in that appearance. If there's a really cool appearance that you believe to be one of a kind, the chances are there are just a lot of genes involved and the odds are low. It may be a couple years until you produce another gecko of the same phenotype...but eventually you will.

When someone tells you crested gecko morphs are polygenic (or "polymorphic" if they really don't know what they're talking about!) and therefore cannot be figured out, you can safely assume they just don't understand genetics and they're using the term "polygenic" to infer that they're too complicated to understand.

This is a myth that has caused serious confusion in the crested gecko world, and I know for a fact it has caused other reptile people, like ball python and leopard gecko breeders, to steer clear of crested geckos. The next time someone tells you crested gecko morphs are different because they're polygenic, remind them that ball python and leopard gecko designer combos are all polygenic and a lot of us understand how they work just fine. ;-)

Myth: The tails of crested geckos don't regenerate or "grow back".

This one isn't harmful to the hobby, and is just something I've put here for fun to mess with people a bit. :-)

Technically speaking, it isn't true that crested gecko tails don't regenerate, and I'll explain why.

When the tail is autotomized (or dropped), technically speaking, new tail tissue and bone does grow back. What grows back, though, is a very short knob-like tail, similar to that of certain species of knobtail geckos. Sometimes the knob-tail will grow back about 1/4" long and occasionally it will grow to about 1/2" long. Philippe de Vosjoli reported that the knob-tail is longer the younger a gecko is when the tail is dropped, but I've never tracked and measured them myself.

But WHY don't they just grow back like normal?
From my experience observing tens of thousands of geckos at various stages in their growth and development cycle, and seeing the movements they make when trying to evade capture (by me), it makes perfect sense that a tail would be a disadvantage for older geckos. The larger a gecko gets, the heavier the tail gets. Not only does the tail weight down the rear end of the gecko, giving it reduced range when jumping, the tail also seems to slow them down on the ground. Fresh hatchlings, however, move very differently. The tail and abdomen move together in a serpentine fashion, with the tail seeming to help propel the gecko forward. When navigating brush or vegetation, hatchlings will often use the "toe pad" on the end of their tail to hold onto things and steady themselves. As they get older, they tend to not do this as often.

As it is the case with frogs, where the tail of tadpoles will eventually shorten and disappear, I believe this tail phenomenon in crested geckos is an evolutionary adaptation that has something to do with their ability to leap great distances, and I think it's actually pretty cool. 

PS: If you insist that every crested gecko you buy has a full tail, you just haven't been doing this long enough.  I've been there too (long ago), but once you do this long enough, you'll come to the conclusion that tails are for hatchling crested geckos and adults aren't really supposed to have one. :-)

I'm sure there are plenty more crested gecko myths out there, but this is all I've had a chance to rant about so far. :-)

If you have any suggestions, shoot me an email!

-AC