The truth is that the regeneration of the tail is not common in vertebrates, but the lizards do it again and again again, although the new tail’s shorter, with a grayish color and without scales or vertebrae (as you can see in the photo below). The latter ones are replaced by a cartilage type tube, and the spinal cord by an epithelial tissue without nerve endings.
This partial “resurrection” happens because it is important for the animal to have the tail in its daily locomotion, for the mating courtship and, what’s more important, as a place to store fats for hard times of hunger or disease. But it’s true that they lack the genetic ability to regenerate other members such as a leg, since in this process it plays an important role the specialized stem cells that activate very specific genes, and in a sequence similar to the embryonic period of the animal . Also, it’s curious that the lizards, like other small saurian, have the ability to voluntarily divest their own tail at critical times; which means, it’s not always lost due to fights, attacks or accidents.
The phenomenon‘s called “caudal autotomy,” and they do it, for example, to mislead their pursuer. At a critical moment in the life of the lizard, when a predator a boy or a broom (their historical nemesis) are chasing it, the animal decides to break its tail and escape. Then there’s a fracture of the vertebral body, where there’s a cartilage disc known as septum that helps in the breakdown. Muscles and blood vessels are prepared to facilitate the tail’s expulsion, and therefore it doesn’t imply the death of the lizard.
because once the tail has fallen, it keeps frantically waving for a while. That will usually entertain the opponent enough time for the gecko to save its own life.
Losing the tail takes its toll on the lizard, cause when it regenerates the tail doesn’t recover the total functionality, and it can happen that two tails grow instead of one.They’ve studied the lizard’s evolution of life once it’s regenerated the tail and checked the animal becomes more elusive and hides more easily.
However, many amphibians, such as salamanders, have the odd feature of regenerating not only the tail, but also other members such as fingers, feet, teeth, crystal, epithelial tissue...