Tale of a Lost Tail

The Desert Spiny lizard (Sceloporus magister), is among the most prominent creatures greeting visitors at Tohono Chul Park in the warm weather. Big, bold and beautiful, with striking colors and eye-catching behavior (these lizards, especially the males, frequently do pushups to advertise their fitness and attract mates), spinies say "Sonoran Desert" as surely as does the saguaro.  

Like other members of the Iguanid family (and other lizards, including geckos), a desert spiny can lose its tail to a predator in a process called autotomy, in which the tail breaks along a fracture plane between two vertebrae. Studies have shown that the lizard is handicapped for some time afterward while it grows a new tail, but it is obviously much better off  than if it had been eaten by the predator!

The tail that regrows is not the same as the original, however. Instead of new vertebrae for support, the regrown tail is composed of cartilage, with long muscles running its length (rather than shorter sets of muscles, as in the original tail). Studies have shown that the new tail does regrow nerves, though it is not known how they compare with the originals.

Above is a photo of a beautiful male spiny I saw at Tohono Chul Park this week, who had fairly recently lost his tail. The photo below more clearly shows the cartilagenous new growth. For a photo of an intact male and the female he has just mated with, see the bonus question in my recent nature quiz.