meet the chimera bearded dragon
If you only look quickly, this bearded dragon may seem pretty normal. But if you look closely you will see that she is the most unique bearded dragon in the world.
That’s because she isn’t a bearded dragon. She is actually two bearded dragons!
She is a chimera, and she exists because of an incredible developmental accident.
The word chimera comes from Greek mythology. A Chimera, shown in this Etruscan bronze statue, was part lion, part goat, and part serpent.
Chimera is now a biology term, but the meaning hasn’t changed all that much. It means that the body of an animal (or plant) is made up of cells with differing DNA. It is a literal fusion of two or more animals in one body.
Normally an animal has exactly the same DNA in all of its cells. But chimeras are born with completely different sets of cells. And each set has its own unique DNA.
The egg that produced our chimera bearded dragon started off containing non-identical twins, also called fraternal twins. Two egg cells were nestled next to each other on the surface of the egg yoke, and were each fertilized by a different sperm. That created two non-identical siblings.
Here is a pair of twins hatching at HereBDragons.
That alone is a unique event, but what happened next is far more rare.
Early on in development, when the embryos were no more then a few cells each, they became stuck together. Nature is amazingly resilient. Instead of dying, or developing into a misshapen animal with too many legs and not enough heads, the embryos blended together perfectly to form one healthy hatchling.
One of the twins became the left side of her body, and the other became the right side. If the traits possessed by those two embryos had been the same then we would have never known that she was a chimera.
Fortunately they were not!
Lots of mutations have been discovered that effect a bearded dragon’s appearance in interesting ways. Those mutations were the giveaway that this dragon is a chimera. You can read all about bearded dragon mutations in this complete guide.
One mutation is called leatherback. As you can see above, the right side of her back, and her right limbs, are covered in smooth uniform scales. That is because the embryo that formed the right side of her body had the leatherback mutation.
Her left side however, has the enlarged spikey scales that are seen in wild bearded dragons. That side formed from an embryo that did not have the leatherback mutation.
Amazingly, that isn’t the only difference between her two sides. In the wild bearded dragons have dark nails, but a mutation called hypomelanism, hypo for short, causes their nails to be clear.
We knew that about half of the hatchlings of this clutch would have clear nails. Our chimera has completely clear nails on the right side of her body, and dark melanin filled nails on the left side.
This means the embryo that formed her right side was a leatherback hypo. And the embryo that formed her left side was a ‘normal’ dragon that does not display either of those traits.
Chimeras are very rare, but the condition is documented in many species, including humans.
Do you know anyone who has eyes that are two completely different colors? The condition is called heterochromia, and it can be caused by chimerism.
Tiger is a Labrador retriever chimera. He is part yellow lab and part black lab. Unlike our bearded dragon, who is divided into two clear sides, Tiger’s two types of cells are jumbled into patches that show the two colors.
Just like with our bearded dragon, we can only spot that Tiger is a chimera because of a mutation that effects appearance.
Yellow labs get their light color from a recessive mutation. If a puppy receives the yellow mutation from both of its parents then it will be yellow. If not then it will be brown or black.
If Tiger had been a chimera of two black labs, then DNA testing could still be used to show that he was a chimera. But we would have no way of knowing just by looking at him.
But it gets even weirder….
In fact, it get so odd, that you may not even believe this next part.
The examples we have looked at have all been animals that have two sets of cells that are from the same species. The two embryos that went into creating them were siblings.
But the chimera of mythology was a blend of completely different species in one body. That couldn’t possibly happen, right?
Amazingly, this also exists!
In 1984 scientists at Cambridge publicized the first goat/sheep chimera. The new creation was called a geep.
Sheep and goats may have some similarities in appearance, but they are two completely different species. They don’t even have the same number of chromosomes.
Since then scientists have succeeded in creating several geeps. Amazingly the combination is stable and they are able to survive to adulthood.
Just like Tiger the labrador, with his yellow and black fur, the geep is a similar patchwork. Areas of the geep’s skin that were formed from the goat embryo have white or black goat fur, while areas formed from the sheep embryo have grey wool.
The geep, and other chimeras, are NOT hybrids. A hybrid is created when members of two species reproduce together, and create an offspring that has DNA from both species within its genome. Every cell of a hybrid has DNA from both parent species. But none of the geep’s cells contain both sheep and goat DNA. Instead it has goat cells, and it has sheep cells.
Through years of selective breeding, bearded dragons are now available in a wide range of colors and traits.
But the chimera dragon is uniquely special. Selective breeding can’t be used to make another like her. Only a spontaneous act of nature can create an animal like this.
Check out the wide range of dragons that we have available. All are bred and hand raised at HereBDragons.